2000 Legacy stalls when clutch is depressed

[2000 Legacy]

Hi everyone,

 

When I got home from work I read the manual for the 3130, "Record by Manual Trigger" and later tried to put it to use. I assumed that the "Trigger Point" we would want is "Middle". Also what points would you want, "All 20", the "Trigger Point", -01...., +01...., or a partial group? Another thing I noticed besides "OL" and "CL" was something called "OL-Drive" which occurred a few times. I'm not sure what this means.

 

I know that you're looking for a few days of "Cold Starts" but thought I'd ask the above questions first. When I first plugged in the 3130 with the key on/engine off the "Live Data" was "OL". I then drove 0.3 mile about 2 minutes later and the car stalled and it was "CL". The car then stalled about 3 more times in a 2 mile drive and like I mentioned above on occasion I would get the "OL-Drive". At this point I hadn't tried the "Manual Trigger".

 

I then drove back home with my son and had him press the trigger when I told him to. The first time I was going about 45 mph, I pushed in the clutch to see if it would shut down, it did and it was "OL". I didn't notice that I could go to "Next" or "Previous" Frames. We then drove about 0.7 mile and came to a stop sign, the car stalled and I had my son press the trigger. The results were "CL" for Frames "-01 thru -06", "-07" was "OL-Drive" and "-08 thru -10" was "CL". The "Trigger Frame, +01 & +02 was "OL", Frame "+03" was "OL-Drive", Frame "+04" was "CL", "+05" was "OL-Drive" and "+06 thru +10 was "CL". I hope that this is presented clearly.

 

As for the "Knock Sensor", I printed out sheet "FU(H4SO)-29" and will compare it to the car tomorrow night/Saturday. Is this one which is from the 2003 Legacy in the same spot and orientation as my 2000 Legacy? I did take a quick look at the Knock Sensor, it appears to be OK. I did'nt see any visible cracks and it appeared to be oriented OK. I did however notice an accorn and shell next to it which tells me squirrels have been nearby. I've noticed this in the past years as well. I did not notice any chewed wires. I should probally remove the Knock Sensor this weekend for a better inspection. Also it was mentioned that the 3130 might be able to get readings on the Knock Sensor, what would it be or how would it read on the 3130?

 

Again thank you all for your help and patience.

2000 Legacy

[OB99W]

I think that the "End" trigger point would provide the most useful data. By the time the button is pressed, the "event" (stall) has already occured -- being able to look back and see what change(s) the ECU saw preceding it should be helpful. Data after a stall would likely be unrevealing, since most of the sensors will have seen dramatic shifts in values at that time. Having all 20 frames would make it more likely to spot a trend.

 

I can't detect a pattern based on the data you've provided so far. Let's see if some more, taken using the "End" trigger point, will help. If you're finding that the stalls occur often enough with the engine warm, then not all the tests have to be run with a cold engine.

 

"OL-Drive" is open-loop operation, but related to driving conditions. The ECU can't use the A/F and other sensors to regulate things well under certain circumstances, such as heavy acceleration (tendency to go too rich) or closed-throttle deceleration (tendency to go too lean), so it uses default values. By the way, there's also "OL-Fault" and "CL-Fault", which the ECU can use if it detects certain sensor failures.

 

Subaru engines from the early 200x's are all very similar, so the 2003 knock sensor info should be applicable to your 2000. With the engine warm and idling, you could check "Spark Adv" with the 3130 while tapping on the knock sensor, as Fairtax4me suggested (although I'd use a wooden dowel or similar material, not something metal), and see if the timing changes much. I've found that checking the sensor's resistance (electrically disconnected from the harness, engine off, measuring between the sensor output lead and engine ground) while tapping can be a better indicator of cracking, etc. If you do either test, let us know what you find.

[Fairtax4me]

(although I'd use a wooden dowel or similar material, not something metal)

I'm not sure if wood would create the type of "ring" that the knock sensor is "listening" for. The knock sensor is "tuned" if you will, to pick up a very specific frequency range around 4000hz IIRC. Metal to metal impact generates a resonant wave closer to this range so the sensor is more likely to pick it up.

But wood is worth a try I suppose.

The only reason I say to use a ratchet extension is because you can't fit a hammer in there to tap on the block with. Use a long 12" extension, hold it vertically a few inches above the block and just let it drop a few inches from the sensor.

[OB99W]

I'm not sure if wood would create the type of "ring" that the knock sensor is "listening" for. The knock sensor is "tuned" if you will, to pick up a very specific frequency range around 4000hz IIRC. Metal to metal impact generates a resonant wave closer to this range so the sensor is more likely to pick it up.

But wood is worth a try I suppose. [...]

For checking whether the sensor is responding to "real" knock, I agree that tapping with metal is the way to go.

 

However, when a knock sensor is failing (usually due to cracks), it sometimes develops a sensitivity that causes it to produce output when it shouldn't. Since there's some (apparently erratic) spark retardation happening, tapping with something non-metallic would tend to show up that sort of failure. So would a resistance check, if the reading is out of spec or changes with impact.

 

I'm just trying to determine if the later than expected spark is a result of the ECU thinking there's too much load, or because the knock sensor is misleading the ECU. (Chicken or egg, again. )

[2000 Legacy]

Hi everyone,

 

With regards to checking the "Knock Sesor":

 

1) If I do the tap test with a wooden dowel, do I tap the sensor itself or around it?

2) If I do the resistance test, do I disconnect at the connection closest to the sensor or the one away from the sensor thats easier to get at?

3) Which is the "Sensor Output Lead"?

 

Results thus far with the 3130:

 

Before work this morning at 4:00 AM I took the car around the block and used the "End" trigger point and got "CL" for the "Trigger" and "-18 thru -1". For trigger "-19" it was "OL-Drive". Note the car stalled at the end of the street/first stop sign 0.2 of mile away from home. I didn't document all the "Adv Spark" data but noticed it ranged from "0" at thr "trigger", "4" at "-16", "36" at "-9", "20" at "-5", "22" at "-3" and "30" at "-1". I'll rerun when I get home tonight.

 

Thanks

2000 Legacy

[OB99W]

With regards to checking the "Knock Sesor":

 

1) If I do the tap test with a wooden dowel, do I tap the sensor itself or around it?

Tap on the sensor itself, both on the flat area near the bolt head, and around the side.

 

 

2) If I do the resistance test, do I disconnect at the connection closest to the sensor or the one away from the sensor thats easier to get at?

Connect wherever it's more convenient for you.

 

 

3) Which is the "Sensor Output Lead"?

The knock sensor wiring may have one or two electrical connections. If there are two, one of them will go to an electrical shield that doesn't actually connect to the sensor element. The element is connected via it's output terminal and the ground connection made by mounting it. The resistance can range from 400 kohms to 700 kohms, and is typically closer to the middle of those values, about 550 kohms. If you ground one lead of your ohmmeter, then placing the other meter lead on the knock sensor output terminal should result in a reading in that resistance range -- a shield connection should be "floating", and have no continuity (infinite resistance) to ground. Assuming a firm connection of the meter leads, the resistance should not vary much, if at all, when the sensor is tapped.

 

 

Results thus far with the 3130:

 

Before work this morning at 4:00 AM I took the car around the block and used the "End" trigger point and got "CL" for the "Trigger" and "-18 thru -1". For trigger "-19" it was "OL-Drive". Note the car stalled at the end of the street/first stop sign 0.2 of mile away from home. I didn't document all the "Adv Spark" data but noticed it ranged from "0" at thr "trigger", "4" at "-16", "36" at "-9", "20" at "-5", "22" at "-3" and "30" at "-1". I'll rerun when I get home tonight.

 

Can we assume that you initiated the trigger as soon as possible after the stall?

[2000 Legacy]

Hi again,

 

I'll start out by answering the question; "Can we assume that you initiated the trigger as soon as possible after the stall?" I beleive I did, I pressed the trigger button as soon as I saw all the lights on the dash start to go out meaning that the car was stalling. I did notice when I pressed the trigger button that it didn't seem to respond so I'd push it again.

 

When I got home this afternoon, about 5:00 PM I connected the 3130 with the key on and engine off and got "OL" and "10" for a "Spark Adv". I then started the car and had to wait a few minutes to get the 3130 into Manual Trigger Mode, I started to pull out of the driveway and stalled, I got out of the driveway and drove about 0.3 miles when the car started to shut down/stalled which meant I pushed in the clutch to come to a stop. I then pulled over and shut the car off with the key on and documented the following; All 20 Frames were "CL" except for "-9 thru -5". The "Spark Adv" ranged from 1 to as high as 32 with the average being about 12.

 

I then restarted the car and drove about 2-3 miles and got up to a speed of 45 mph and pused in the clutch as if I was pulling over or coming to a stop. Everything started shutting down so I pressed the trigger, pulled over shut the car off but left the key on and got the following: "OL-Drive" at "Trigger", "-17, - 16, -4, and -1", respectively the "Spark Adv" was 35, 10, 28, 22, and 30. All the other "Frames" were "CL" (-19, -18, -15 thru -5, -3 and -2). The "Spark Adv" respectively was; 30, 18, 34, 30, 24, 25, 32, 21, 23, 30, 34, 17, 26, 15 and 34.

 

I restarted the car and drove home about 8 miles, back into the driveway and let the car idle with the 3130 connected and documented with no tap that the "Spark Adv" was 4, 11, 5 and 9. It seemed to go up and down. I then tapped the top of the "Knock Sensor" bolt and around it with a 3/8' wooden dowel and it didn't seem to affect the "Spark Adv" readings at all, they ranged from 4 - 12 and got as high as 13. I tried tapping harder and still didn't get any response. I shut the car off and proceded to remove the sensor.

 

I disconnected the negative battery, unbolted the sensor and tried to unplug it. It had 2 connections, a red one at the sensor and a white one further up. I tried to unplug the red one but couldn't, I finally got the red part off but nothing else. So I tried to "Back Probe" where the red part was. There were 2 wires at this point, a light blue and white. I tried both with my red probe on my cheap multimeter that was set to 2000K ohms and seemed to get more results with the light blue wire, I then put the black lead of the meter to the metal on the car and got about -400 ohms. It seemed to drop the longer I held it. I then inspected the "Knock Sensor" and it looks as though there is a hairline crack on the plastic part (outside shell) of it. There also appeared to be a seam. I hope that this is suffient and apologize for the long winded response. I'm just trying to give you all the information since I'm not quite sure about what I'm doing.

 

Do you think we need any more "Manual Trigger" documentation on whether or not it is "CL" or "OL"?

 

Did I provide enough information on the "Knock Sensor"?

 

It looks as though I'll need the "Knock Sensor" at a minimum but wonder if I shouldn't just get the "A/F (O2) Sensor" as well. What are your thoughts?

 

If you think we should replace the "A/F (O2) Sensor", I'd like to order it tomorrow so that I can have it for my Adult Auto Class next week where I'd hopefully have access to a lift.

 

I know I've said it many times, but thanks to everyone.

 

 

Sincerely,

2000 Legacy

[OB99W]

The resistance test didn't actually check the knock sensor, since by dismounting it, it was disconnected from the circuit. As I tried to explain, one connection of the sensor is made to ground via being mounted by the bolt. The way your meter was used, it was connected to (and measured) the ECU's knock sensor input. (This isn't meant to fault you -- it's more of a realization on my part of the difficulty in conveying certain information.) With no change occuring in the ignition timing when tapping on the knock sensor, it might be that the sensor is okay, even with the single hairline crack you noticed.

 

As you noted, based on the data, the system is going from "CL" to "OL-Drive" at some point preceding the stall. As I explained previously, that would be expected when decelerating for a stop (closed throttle). When "OL" (due to drive conditions or otherwise), the A/F sensor output is ignored by the ECU, and therefore there's no feedback to the ECU at that time about the mixture, meaning it falls back to default values and can't correct for certain possible faults. Once the engine revs drop to near idle speed, the system should go back to "CL", when the ECU uses A/F data again. However, if the engine is already faltering, the feedback might be too late to allow for a recovery, especially if the A/F sensor is sluggish in operation.

 

So, since you have the Adult Auto Class coming up, I have one more idea before you "bite the bullet" and replace the A/F sensor (and possibly the knock sensor). If it can be done at the class, I suggest that you check the fuel pressure that the FPR is providing to the injectors at idle. In order to make sure that low engine vacuum isn't causing the FPR to raise the pressure, you can disconnect the vacuum line coming from the engine, plug it, and connect a hand vacuum pump to the FPR, pumped to about 20 in Hg. If the fuel pressure is too high then, either the FPR is bad or the return line is blocked. If the pressure is correct, I'd take a chance on the A/F sensor.

 

I'm wishing you some good luck at this point!

[OB99W]

I don't think I've ever before made this much effort to diagnose in order to avoid "trying" parts. Don't get me wrong, I'm not complaining, it's good brain exercise. After posting last night, I awoke this morning and realized that we should look more closely at what I wrote in the second paragraph of my previous post (#158).

 

I'd like you to try the manual trigger live data capture a couple more times, with the engine at least somewhat warm. In order to see if the problem relates to CL - OL-Drive - CL transitions, it would be very helpful to have slightly different data. The values to obtain are the Fuel Sys (OL, CL or OL-Drive), STFT, LTFT, and Calc Load for all 20 frames.

 

If the results are sufficiently clear, this could point more directly to the culprit. If not, the fallback is what I wrote in the last paragraph of post #158.

[2000 Legacy]

Sorry that I didn’t do the resistance test on the knock sensor the way you intended. It’s not you, it’s my inexperience. I don’t mean to give you unnecessary brain exercise, I’m sure you get plenty. As for the pressure test at the FPR I was a little confused.

1) What was meant by “plug it”, the vacuum hose that was connected to the FPR?

2) And then connect the vacuum pump to where the vacuum hose was?

3) Once it’s pumped to 20 in Hg, what will happen (nothing, drop, rise)?

4) Is the car idling once the pump is pumped up?

5) What’s the correct pressure?

Also, since I disconnected the negative battery last night to inspect the Knock Sensor I cleared the CEL’s so today after driving about 25 miles the CEL came back on. I know, no surprise. Anyways I documented the Freeze Frame Data: The CEL was P0304 (Cyl No. 4 Misfire).

Fuel Sys = OL

Calc Load = 133

ECT = 78

STFT = 0

LTFT = -1.5

MAP = 16/2

RPM = 1429

Veh Speed = 0

 

I did the Manual Trigger Data and got the following results. Please note that I started at Frame “Trigger” to Frame “-19” to “-1”. Where the results were the same I tried to group them.

 

2:00 PM, Note the car didn’t stall but felt like it was going too and I had pushed the trigger. The car had been running about 10 minutes/5 miles.

Fuel Sys: “OL” for Trigger, “CL” for -19 thru -7, -5 & -1 and “OL-Drive” for -6, -4 thru -2.

STFT B1 (%): 0.0, 0.7, 0.0, -1.5, -1.5, -2.3, 2.3, -3.1, -1.5, -0.7, -3.1, -3.1, 3.9, 0.7, -4.6, -25.0, 0.0, 0.0, 0.0, -10.9.

LTFT B1 (%): “-1.5” for Trigger, -19 thru -12 & -3 thru -1. “-2.3” for -11 thru -9, “3.9” for -8 thru -6 and “3.1” for -5 thru -4.

Calc Load: 11.7, 42.7, 44.7, 47.0, 51.7, 42.3, 36.4, 39.6, 39.2, 43.9, 45.0, 43.5, 28.2, 39.2, 24.3, 17.6, 8.6, 10.1, 12.1, 7.4.

STFT B1 S2 (%): 0.7 for Trigger, -19 thru -10 & -8 and 0.0 for -9 & -7 thru -1.

 

3:00 PM, Note the car had been running about 10 minutes/10 miles when I pushed in the clutch and everything started to shutdown. I pressed the trigger then popped the clutch to keep the car going then pulled over to document.

Fuel Sys: “OL-Drive” for Trigger, -16 & -3. “CL” for -19 thru -17, -15 thru -4, -2 & -1.

STFT B1 (%): 3.1, 0.0, -1.5, 1.5, 0.0, 0.0, -10.9, 3.1, -16.4, -2.3, 1.5, 2.3, 3.1, -16.4, 4.6, 3.9, 4.6, -7.0, 3.1, 1.5.

LTFT B1 (%): “-3.1” for Trigger, -19 thru -16, -14, -13, -11 thru 9, -5, -3 & -2. -2.3 for -15. -3.9 for -12, -8 thru -6, -4 & -1.

Calc Load: 3.9, 32.5, 24.3, 28.6, 43.9, 46.6, 42.7, 34.9, 15.2, 30.1, 27.8, 33.3, 25.0, 10.9, 24.7, 32.9, 22.3, 8.6, 30.9, 16.0.

STFT B1 S2 (%): 0.7 for Trigger, -16 & -15. 0.0 for -19 thru -17 & -14 thru -1.

 

9:00 PM, The car had been sitting for about 3 hours, I drove it a short distance and it sat for about an hour. I restarted it and ran it for about 10 minutes when it stalled.

Fuel Sys: “OL” for Trigger. “CL” for -19 thru -16, -14 thru -9, -7 & -5 thru -3. “OL-Drive” for -15, -8, -6, -2 & -1.

STFT B1 (%): 3.9, 0.0, -10.1, 2.3, -2.3, 0.0, -11.7, -23.4, -20.3, 4.6, 0.0, -3.9, 0.0, 0.0, 2.3, 2.3, 0.0, -1.5,-2.3, -7.8.

LTFT B1 (%): -3.9, -4.6, -4.6, -3.9, -3.9, -3.9, -3.9, -3.9, -3.9, -4.6, -3.9, -6.2, -4.6, -3.9, -3.9, -3.1, -3.9, -3.9, -4.6, -4.6.

Calc Load: 0.0, 7.4, 21.9, 27.4, 26.6, 6.6, 6.6, 6.2, 4.7, 28.6, 45.4, 17.2, 50.1, 39.6, 16.4, 32.5, 9.0, 32.1, 10.5, 7.8.

STFT B1 S2 (%): “0.0” for Trigger, -19 thru -12, -10, & -7 thru -1. “-0.7” for -11, -9 & -8.

 

10:00 PM,

Fuel Sys: “OL” for Trigger. “CL” for -19 thru -1.

STFT B1 (%): 0.0, -12.5, 9.3, 0.0, 9.3, 2.3, 7.0, -0.7, -10.9, -7.8, 8.5, 4.6, -18.7, 6.2, 3.1, 6.2, 6.2, 3.9, -20.3, -3.1.

LTFT B1 (%): -6.2, -7.0, -7.8, -5.4, -6.2, -3.9, -4.6, -7.8, -7.8,-9.3, -6.2, -7.8, -7.0, -8.5, -8.5, -8.5, -7.8, -9.3, -8.5, -10.1

Calc Load: 7.0, 14.5, 34.9, 10.9, 36.4, 35.6, 35.2, 15.6, 14.5, 14.1, 25.0, 21.1, 28.6, 25.4, 21.5, 29.0, 17.2, 18.0, 40.0, 12.5.

STFT B1 S2 (%): “0.0” for Trigger & -19, -17 thru -1 and “).7” for -18.

 

Hope this helps. Thanks for everything.

 

2000 Legacy

[OB99W]

Sorry that I didn’t do the resistance test on the knock sensor the way you intended. It’s not you, it’s my inexperience. I don’t mean to give you unnecessary brain exercise, I’m sure you get plenty.

No problem.

 

 

As for the pressure test at the FPR I was a little confused.

I'm trying to make sure that the fuel pressure measurement at idle is done with the FPR seeing vacuum typical of a well-functioning engine. That's why I'm suggesting taking the pressure reading while there's 20" applied, rather than something possibly several inches lower (that your intake might be at).

 

 

1) What was meant by “plug it”, the vacuum hose that was connected to the FPR?

2) And then connect the vacuum pump to where the vacuum hose was?

Yes to 1) and 2).

 

 

3) Once it’s pumped to 20 in Hg, what will happen (nothing, drop, rise)?

I'm not sure exactly what you're asking. Assuming the FPR's diaphragm is okay, the vacuum will hold at whatever it's been pumped to. If we're talking about engine idle, change should be minimal as compared to (let's say) 17".

 

 

4) Is the car idling once the pump is pumped up?

Once the fuel pressure gauge and vacuum hand pump are attached, the engine should be run. A fuel pressure reading can be done with the FPR initially having no vacuum applied, and then 20". You could even monitor the change in fuel pressure as the vacuum to the FPR is changed.

 

 

5) What’s the correct pressure?

With no vacuum applied to the FPR, fuel pressure should be about 43 psi. With 20" vacuum applied, about 32 psi. Both should preferably be within plus/minus 5% (10% max).

 

Be sure to take care when "T"-ing in the fuel pressure gauge, since there will initially be pressure in the line even with the engine off (unless your injectors are very leaky).

 

The diagnostic info in the FSM for P0172 goes into detail concerning the above. Please read it.

 

 

Also, since I disconnected the negative battery last night to inspect the Knock Sensor I cleared the CEL’s so today after driving about 25 miles the CEL came back on. I know, no surprise. Anyways I documented the Freeze Frame Data: The CEL was P0304 (Cyl No. 4 Misfire).

Fuel Sys = OL

Calc Load = 133

ECT = 78

STFT = 0

LTFT = -1.5

MAP = 16/2

RPM = 1429

Veh Speed = 0

Those readings are strange. I suspect two of them are typos. "Calc Load" can't exceed 100% (and I doubt the engine was that stressed ), so it's probably "13.3", not "133". For "MAP, it seems likely you hit one key over, so that should be "16.2". The rest of the readings don't fit the car having just been driven 25 miles. Unless things are so bad that the catalyst is ready to melt, a misfire requires two trips to trigger the CEL. Therefore, the freeze frame data was likely captured at the first trip (when the code was "pending") -- this was likely at a cold start, which would explain being "OL", the ECT of only 78 degrees, the 1429 RPM (cold idle?), and the Veh Speed indicating the car wasn't moving ("0").

 

This is already getting long, so I'll comment about the captured live data in a following post.

[OB99W]

I did the Manual Trigger Data and got the following results. Please note that I started at Frame “Trigger” to Frame “-19” to “-1”. Where the results were the same I tried to group them.

I reformatted the data into tables, which makes it somewhat easier to see relationships and trends. Since some values in the trigger frame data seem to be "outliers" (look at the "Calc Load" values in particular), I'm only showing frames -19 thru -1. I added leading zeroes ("0") and other spacers as needed to keep the columns as even as possible.

"CL--" = "CL" (closed loop)

"OLD" = "OL-Drive" (open loop, due to driving conditions)

 

All below have the form:

{frame #}*{Fuel System Status}*{STFT B1}**{LTFT B1}**{Calc Load}**{STFT B1 S2}

 

2:00 PM, Note the car didn’t stall but felt like it was going too and I had pushed the trigger. The car had been running about 10 minutes/5 miles.

-19*CL--*+00.7**-1.5**42.7**0.7

-18*CL--*+00.0**-1.5**44.7**0.7

-17*CL--*+01.5**-1.5**47.0**0.7

-16*CL--*-01.5**-1.5**51.7**0.7

-15*CL--*-02.3**-1.5**42.3**0.7

-14*CL--*+02.3**-1.5**36.4**0.7

-13*CL--*-03.1**-1.5**39.6**0.7

-12*CL--*-01.5**-1.5**39.2**0.7

-11*CL--*-00.7**-2.3**43.9**0.7

-10*CL--*-03.1**-2.3**45.0**0.7

-09*CL--*-03.1**-2.3**43.5**0.0

-08*CL--*+03.9**+3.9**28.2**0.7

-07*CL--*+00.7**+3.9**39.2**0.0

-06*OLD*-04.6**+3.9**24.3**0.0

-05*CL--*-25.0**+3.1**17.6**0.0

-04*OLD*-00.0**+3.1**08.6**0.0

-03*OLD*-00.0**-1.5**10.1**0.0

-02*OLD*-00.0**-1.5**12.1**0.0

-01*CL--*-10.9**-1.5**07.4**0.0

 

 

3:00 PM, Note the car had been running about 10 minutes/10 miles when I pushed in the clutch and everything started to shutdown. I pressed the trigger then popped the clutch to keep the car going then pulled over to document.

-19*CL--*-00.0**-3.1**32.5**0.0

-18*CL--*-01.5**-3.1**24.3**0.0

-17*CL--*+01.5**-3.1**28.6**0.0

-16*OLD*-00.0**-3.1**43.9**0.7

-15*CL--*-00.0**-2.3**46.6**0.7

-14*CL--*-10.9**-3.1**42.7**0.0

-13*CL--*+03.1**-3.1**34.9**0.0

-12*CL--*-16.4**-3.9**15.2**0.0

-11*CL--*-02.3**-3.1**30.1**0.0

-10*CL--*+01.5**-3.1**27.8**0.0

-09*CL--*+02.3**-3.1**33.3**0.0

-08*CL--*+03.1**-3.9**25.0**0.0

-07*CL--*-16.4**-3.9**10.9**0.0

-06*CL--*+04.6**-3.9**24.7**0.0

-05*CL--*+03.9**-3.1**32.9**0.0

-04*CL--*+04.6**-3.9**22.3**0.0

-03*OLD*-07.0**-3.1**08.6**0.0

-02*CL--*+03.1**-3.1**30.9**0.0

-01*CL--*+01.5**-3.9**16.0**0.0

 

 

9:00 PM, The car had been sitting for about 3 hours, I drove it a short distance and it sat for about an hour. I restarted it and ran it for about 10 minutes when it stalled.

-19*CL--*-00.0**-4.6**07.4**0.0

-18*CL--*-10.1**-4.6**21.9**0.0

-17*CL--*+02.3**-3.9**27.4**0.0

-16*CL--*-02.3**-3.9**26.6**0.0

-15*OLD*-00.0**-3.9**06.6**0.0

-14*CL--*-11.7**-3.9**06.6**0.0

-13*CL--*-23.4**-3.9**06.2*0.0

-12*CL--*-20.3**-3.9**04.7**0.0

-11*CL--*+04.6**-4.6**28.6**-0.7

-10*CL--*-00.0**-3.9**45.4**0.0

-09*CL--*-03.9**-6.2**17.2**-0.7

-08*CL--*-00.0**-4.6**50.1**-0.7

-07*CL--*-00.0**-3.9**39.6**0.0

-06*OLD*+02.3**-3.9**16.4**0.0

-05*CL--*+02.3**-3.1**32.5**0.0

-04*CL--*-00.0**-3.9**09.0**0.0

-03*CL--*-01.5**-3.9**32.1**0.0

-02*OLD*-02.3**-4.6**10.5**0.0

-01*OLD*-07.8**-4.6**07.8**0.0

 

 

10:00 PM,

No details of running circumstances available?

-19*CL--*-12.5**-7.0**32.5**0.0

-18*CL--*+09.3**-7.8**24.3**0.7

-17*CL--*+00.0**-5.4**28.6**0.0

-16*CL--*+09.3**-6.2**43.9**0.0

-15*CL--*+02.3**-3.9**46.6**0.0

-14*CL--*+07.0**-4.6**42.7**0.0

-13*CL--*-00.7**-7.8**34.9**0.0

-12*CL--*-10.9**-7.8**15.2**0.0

-11*CL--*-07.8**-9.3**30.1**0.0

-10*CL--*+08.5**-6.2**27.8**0.0

-09*CL--*+04.6**-7.8**33.3**0.0

-08*CL--*-18.7**-7.0**25.0**0.0

-07*CL--*+06.2**-8.5**10.9**0.0

-06*CL--*+03.1**-8.5**24.7**0.0

-05*CL--*+06.2**-8.5**32.9**0.0

-04*CL--*+06.2**-7.8**22.3**0.0

-03*CL--*+03.9**-9.3**08.6**0.0

-02*CL--*-20.3**-8.5**30.9**0.0

-01*CL--*-03.1**-10.1**16.0**0.0

 

In the above tables, there are several instances of the STFT being in the region of -20 to -25. (That's due to the ECU seeing the need to substantially lean the mixture.) It's typically happening about the time that the load is significantly reduced (probably with foot off throttle), and mostly shortly after the ECU switches from closed-loop to open-loop-drive.

 

In all cases, the system is initially CL, which means the A/F sensor is in play. It apparently transitions to OL-Drive during deceleration when the throttle is closed (expected behavior). So, if either the fuel pressure is out of spec or the A/F sensor is sluggish, the mixture might overshoot enough to cause the problem. (The dealer induction service and replacement of IACV & injectors, and further IACV cleaning that was done, none of which resolved the problem, hopefully allows a rule-out of those as possible culprits. )

 

I'm back to the suggestion of checking the fuel pressure, doing something about it if it's out of spec, and if that leads nowhere then chancing a new OEM front A/F sensor. (Hmmm, did anyone check for holes in the exhaust system? :-\)

 

Good luck!

[2000 Legacy]

Hi,

 

I can't thank you enough for all your time and effort. I did fat finger my reply early this morning. The "Calc Load" was 13.3 and the "MAP" was 16.2 for the Freeze Frame Data yesterday. I had written Post #160 which took me 2 plus hours and when I went to submit it I got booted out. So I rewrote it. Sorry. I like your idea of the tables you put together, wish I had thought of that. A while back I tried to insert an excel document but failed. Oh well hopefully we're coming to the end. I'm getting tired and you must be too.

 

I tried to go and buy a cheap Fuel Pressure gauge/vacuum pump but the cheapest around town was like $50.00. I read your Post #161 along with the diagnostic for P0172. I assume that your'e suggesting I do "No. 4" for DTC P0172. I think I have an idea of how to do this, Release the Fuel Pressure as stated in "No. 3, Step 1", disconect the vacuum hose to the FPR, plug it, connect the hand pump to the FPR along with the gauge (is this where the "T" comes into play?), pump it up to 20", take a reading, start the car, let it idle and take another reading.

 

I know this may sound stupid but if this were a fuel problem, wouldn't the car run crappy all the time and not just at initial starts/stops?

 

I'm leaning torwards just buying the "A/F (O2) Sensor" since I have no record of it being changed and since back in 2008 I had 2 CEL's for it which I cleared. This may have been a big mistake on my part. However if changing the sensor at this point worked I would be so excited. I'm sure you'd be pretty happy as well. Any thoughts?

 

Thanks

2000 Legacy

[OB99W]

[...]I had written Post #160 which took me 2 plus hours and when I went to submit it I got booted out. So I rewrote it. Sorry.

I've had that sort of thing happen to me in the past, and not just on this site. I now import the post to which I'm responding into a word processor (actually, it's just Windows Notepad), and write my reply. I save that frequently as I'm writing, because power glitches have also "eaten" things before. When I'm done, I copy it to the online reply form. If it gets "lost", I still have my original. (I'll admit it took a few frustrating experiences to get me to do that.)

 

 

I like your idea of the tables you put together, wish I had thought of that. A while back I tried to insert an excel document but failed. Oh well hopefully we're coming to the end. I'm getting tired and you must be too.

Thanks, tables are good, graphs even better, but there's a limit... I'm not "tired", but I'll admit this is getting "just a bit" drawn out.

 

 

I tried to go and buy a cheap Fuel Pressure gauge/vacuum pump but the cheapest around town was like $50.00.

I was thinking that your Adult Auto class might have a gauge available. If not, Equus has a decent gauge with accessories (no, I don't have stock in the company, I just like some of their products ). As much as I don't like Walmart, they have a good deal on the Equus 3640. If you have a local Walmart, you can order it online and have it sent to the store for pickup.

http://www.walmart.com/ip/Equus-3640-Innova-Professional-Fuel-Injection-Pressure-Tester/14644670

 

For a vacuum pump, there's always an Equus 3660. But seriously, you can probably get away with not using one. I'll explain as I go on (and on, and on...).

 

 

I read your Post #161 along with the diagnostic for P0172. I assume that your'e suggesting I do "No. 4" for DTC P0172. I think I have an idea of how to do this, Release the Fuel Pressure as stated in "No. 3, Step 1", disconect the vacuum hose to the FPR, plug it, connect the hand pump to the FPR along with the gauge (is this where the "T" comes into play?), pump it up to 20", take a reading, start the car, let it idle and take another reading.

That isn't quite what I had in mind. Perhaps it would help if I explained how the FPR works:

Fuel is pumped from the gas tank, through the filter in the engine compartment, and then into a line that delivers it to the left (driver) side fuel rail to which the injectors are mounted. It then crosses through a line over to the front of the right side fuel rail. The FPR "inlet" is mounted to the rear end of that right side rail, and whatever fuel is excess to maintaining the correct pressure in the rails exits the FPR "outlet" and is returned via a line to the tank. What the "correct" pressure is depends on engine load, determined by the magnitude of the intake vacuum applied to the FPR's diaphragm.

 

I'll describe a procedure that doesn't use a hand-operated vacuum pump (although steps 3 and 4 in the manual are pretty much it).

1) Safely release pressure in the fuel lines.

2) Disconnect the fuel hose/line that goes to the engine from the fuel filter outlet.

3) "T" in the fuel pressure gauge between the fuel filter outlet and the hose feeding the engine.

4) Attach a vacuum gauge to the intake manifold as you've done in the past.

5) Start the engine.

6) Run until the idle is relatively stable, and intake vacuum is at least 17".

7) Note the fuel pressure. It should be about 32 psi.

8) Disconnect the vacuum hose at the FPR and plug the loose hose end.

9) Note the fuel pressure again. It should be about 43 psi.

10) Shut off the engine.

11) Don't immediately disconnect the gauge. Instead, get an idea of how rapidly the pressure drops, which will be an indication of whether any of the injectors are leaking, among other things.

12) After a couple of minutes or so, safely release the fuel pressure again.

13) Remove the pressure and vacuum gauges and reconnect lines as needed.

 

The pressure measured with the FPR's vacuum line attached (step 7) may be slightly higher than normal if the engine vacuum is low.

 

 

I know this may sound stupid but if this were a fuel problem, wouldn't the car run crappy all the time and not just at initial starts/stops?

If only all this was that easy. For one example, let's say that (either due to a bad/obstructed FPR or a blocked fuel return line) the pressure going to the injectors is too high. At idle, the amount of fuel needed is considerably less than at higher engine loads. Only so much air is available, via the IACV, to mix with it. If it's really rich, the plugs could be fouling, leading to misfire. (We know, based on the LTFT numbers, that the ECU thinks it's too rich.) With the engine cold enough for the system to be running OL, the default fuel map (not to be confused with the MAP sensor) already calls for enrichment, and if the fuel pressure is too high and even more fuel is therefore injected, the ECU doesn't know that and couldn't do anything about it anyway.

 

For another example, let's assume that the A/F sensor is very sluggish to respond. Then, it might have a hard time keeping up with the changes that occur with closed-throttle deceleration when going from CL to OL-Drive and back again. The response time should be a fraction of a second for decent control. In most cases, one second is too long, and triggers P0133.

 

On the other hand, the further above idle speed/load, the greater the volume of fuel and air passing through the engine. Small leaks, excesses and deficits that impact idle get swamped out, and while everything might not be running exactly as planned, the end result is often hardly noticable. Sometimes (other than drivability problems at low speeds) a loss in gas mileage can be the only clue that something is amiss.

 

I'm leaning torwards just buying the "A/F (O2) Sensor" since I have no record of it being changed and since back in 2008 I had 2 CEL's for it which I cleared. This may have been a big mistake on my part. However if changing the sensor at this point worked I would be so excited. I'm sure you'd be pretty happy as well. Any thoughts?

We've been talking about changing the A/F sensor throughout much of this thread, but realizing that other things could be the cause of the problem, we did a lot more diagnostic testing and some procedures to rule those out. That sensor is old, has a lot of miles on it, has triggered codes, etc. It should be replaced. I would be delighted to have it resolve the problem. But (yeah, there's always one of those), if the mix is too rich because of a fuel pressure problem, after a short time it can affect the new A/F sensor.

 

So, I'd suggest checking fuel pressure, if not before replacing the A/F sensor, then within some reasonable time afterward.

 

And yes, I think we'd both like to see a happy ending for this sometime soon.

[2000 Legacy]

Hi,

 

Sounds like a plan, I'll check with my instructor in my Adult Education Class to see if he has access to the gauge and hand pump so that we can check the fuel pressure. Someone a t work said that they were like $5.00 - $10.00 which if that were the case I would have bought it and tried to do it on my own in the driveway. I was hoping that I could have had the fuel pressure diagnosed prior to class so that maybe I might have been prepared for the next move. Oh well it's been a problem for a long time another week isn't going to that much difference. I'll keep you posted. Thanks for everything.

 

2000 Legacy

[OB99W]

Sounds like a plan, I'll check with my instructor in my Adult Education Class to see if he has access to the gauge and hand pump so that we can check the fuel pressure. Someone a t work said that they were like $5.00 - $10.00 which if that were the case I would have bought it and tried to do it on my own in the driveway.

The least I've seen 0-100 psi fuel pressure gauges go for (on eBay, anyway) is about $16 including shipping charges. That's just for the gauge -- you'd then need at least some hose, hose clamps, and a "T". The Equus unit I linked to has all that, plus the nice feature of a built-in way of safely and easily depressurizing after you're done testing. (Sorry if that sounds like an ad. )

 

By the way, I found a pretty good diagram of a generic fuel injection system, although it omits showing the vacuum line to the FPR. Of course, the Subaru has two fuel rails "in series", rather than the single one shown:

http://www.2carpros.com/how_does_it_work/images/fuel_injection_system.jpg

 

 

I was hoping that I could have had the fuel pressure diagnosed prior to class so that maybe I might have been prepared for the next move. Oh well it's been a problem for a long time another week isn't going to that much difference. I'll keep you posted. Thanks for everything.

I can appreciate your wanting to move this along, and I admire your dedication.

Edited October 11, 2010 by OB99W

[2000 Legacy]

Hi everyone,

 

Just to give you an update. I've checked around for a "Fuel Pressure Gauge", I thought if I went to the Walmart store I'd find it but unfortunately I can only get it through the internet. I tried Advanced and Auto Zone, no luck. So by the time I checked these places out I had my Adult Auto Class and one of the instructors said he had one that he'd bring it to next weeks class. I'll keep you posted.

 

Thanks for the diagram of the fuel injection system and for everything else.

 

2000 Legacy

[OB99W]

Yes, if you want to get that fuel pressure gauge from a local Walmart, you have to place the order via the net and then elect to have it sent to the store for pickup. It's good that you'll be able to use one in the class.

[2000 Legacy]

Hi everyone,

 

We finally got the fuel pressure measurements, they are as follows:

 

44 PSI at 17" vacuum

 

when we removed the vacuum hose at the FPR the fuel pressure gauge jumped to 50 PSI. It was noted that it didn't seem to make a difference whether or not the loose end of the vacuum hose to the FPR was plugged or not.

 

My instructor even tried tapping the FPR with a ratchet which didn't affect the fuel pressure gauge.

 

We then shut the car off and the fuel presssure guage I thought read 42 PSI, 4 minutes later it was 44 PSI and it remained at 44 PSI for 10 minutes before we disconnected everything.

 

Hope this helps to get us closer to resolving this issue. As always thanks for the input and help.

 

2000 Legacy

[OB99W]

The fact that the pressure readings are holding after shutting the engine down is good -- it means the injectors aren't leaking.

 

 

It was noted that it didn't seem to make a difference whether or not the loose end of the vacuum hose to the FPR was plugged or not.

I wouldn't have expected much change in the idle with a small vacuum leak caused by the hose being left open, but we shouldn't gloss over this. You should verify that there is full vacuum at that hose, just in case something is blocking it.

 

However, assuming vacuum is getting there and the gauge you used is in good calibration, it looks like there is a problem with the FPR. The pressure you read is considerably too high -- since your engine vacuum at idle is somewhat lower than normal (17'' versus 19-20"), I'd have expected the pressure to have been slightly above the typical 32 psi -- perhaps 33-34. The pressure with vacuum to the FPR removed, which should be about 43 psi, at 50 psi is also too high -- obviously, engine vacuum has no effect on that.

 

Besides the FPR itself, another thing that can cause the fuel pressure to be excessive is a blocked return line (that's the one that runs from the outlet of the FPR back to the gas tank). However, it's much less likely than the FPR itself being bad.

 

You could depressurize the fuel lines, disconnect the return line from the FPR, remove the gas filler cap, and apply some low pressure/velocity air to the return line (under about 5 psi). That should easily blow any gas in the line back into the tank, and you might be able to hear the air escaping into the tank by listening at the filler. If the air can't push the fuel through the return line, inspect the line.

 

Or, you could take a chance, not check the return line, and just replace the FPR. If you do so, clearing the ECU so that it can start "clean" and relearn settings would be a good idea.

 

Hope this helps to get us closer to resolving this issue.

It just might have done that.

 

 

EDIT: If you don't have a source of air for checking the fuel return line, a hand-operated tire pump with gauge could be fairly easily adapted for the purpose. When connected, keep it higher than the return line, in order to minimize the chance that gas will wind up in the pump.

 

Not very expensive:

http://www.google.com/products?hl=en&safe=off&q=tire%20pump%20with%20gauge&um=1&ie=UTF-8&sa=N&tab=wf

Edited October 22, 2010 by OB99W

[2000 Legacy]

Hi everyone,

 

We just blew air into the return line from the FPR. We depressurized the system and tried to disconnect the return line from the FPR, because the rubber hose was so short we couldn't get it off so we removed the FPR and blew air into the end of the short piece of hose. At first some gas blew back at us or the air hose, but after that we could hear air in the gas tank from the filler cap. We also inspected the short vacuum line from the FPR to the intake manifold, it was clear. We did notice that the end of the vacuum hose that connects to the intake seems somewhat loose, so we tie-wrapped it.

 

We then took the car around the block, it stalled a few times. Backed it into the driveway and could smell gas pretty good, so we left the car running and popped the hood. Gas was leaking from the bottom of the FPR. We're guessing it's becuase we didn't replace the "O" ring on the FPR or lube it with oil.

 

I couldn't find any information about the FPR in the FSM, I thought for sure it would be in the fuel section. I went into the other folders as well and still couldn't find it. I did find it in my Haynes book.

 

So it looks as though we'll have to order a new FPR. I would assume OEM, correct? Am I correct in assuming that the new FPR will come with a new "O" ring? Also while I'm at it should I order the front "O2 A/F Sensor"? Did we ever decide that this was a contributing factor even though we know it should be replaced or do we replace the FPR and then see what that does?

 

One more question, when we replace the FPR you say we should clear the ECU, I am I correct in saying that you mean we erase the codes with the 3130

?

 

 

Thanks for everything.

2000 Legacy

[OB99W]

Okay on being able to pass air through the return line. That eliminates it as a cause of the high fuel pressure, leaving the FPR.

 

Yes, the leak is probably due to the O-ring having gotten damaged or no longer being resilient. It should be replaced if you intend to drive before you get the new FPR -- please don't use the car while there's a gas leak.

 

You're right, the manual doesn't seem to have a section concerning R&R of the FPR. Who needs service info, anyway?

 

The FPR typically comes with an O-ring already installed in the groove (but you should probably verify that from wherever you purchase the FPR, just to be sure). Yes, I would suggest OEM. More and more aftermarket parts seem to be coming from questionable suppliers. (The recall problems that Toyota and Honda have been having lately might be traced back to from whom they're buying parts, so it isn't just the aftermarket in some cases.)

 

As to the front A/F sensor -- as we've discussed before, it should probably be replaced eventually. Whether you purchase it along with the FPR is a personal decision. What I would advise is that you change the FPR first, just to see what effect that has, including checking gas mileage (I'd expect at least a slight improvement). If the car seems to run okay, and gets adequate mileage, you might be able to put off the A/F sensor a bit longer. If there's still a drivability problem after changing the FPR, or the mileage isn't enough improved, then I wouldn't wait to change the A/F sensor. Replacing a sluggish sensor that's sufficiently impacting gas mileage can actually pay for itself in reduced gas expense.

 

Once the FPR is replaced, the ECU should have it's memory erased, either via the 3130 or by disconnecting the battery for a while. The reason I'm suggesting that is primarily because the long term fuel trim is probably compensating for the excessive fuel pressure -- once the pressure is correct, the current LTFT would be incorrect and confuse things.

[2000 Legacy]

Thanks for everything. I'll order the new OEM FPR and let you know how we make out. I'm hoping this is it. We won't drive the car until the new FPR is installed and the ECU is cleared.

 

2000 Legacy

[2000 Legacy]

Hi everyone,

 

I just finished replacing the FPR (Fuel Pressure Regulator). I checked the codes with the 3130 (all 4 cylinder misfires, no surprise), depressurized the fuel system, disconnected the negative and positive battery cables which cleared the codes/ECM, removed the FPR, put a light coat of oil (5W-30) on the "O" ring of the new FPR, installed the FPR and reconnected everything. I then checked for codes with the 3130, none of coarse. This all took about 45 minutes. I started the car, checked for leaks and drove about 2.5 miles, it stalled quite a few times and seem to run rougher than usual. There also seemed to be a burning smell, not like the one I've smelled in the past however once I got to where I was going, a minute later, I popped the hood and didn't see or smell anything.

 

The car sat for about 45 minutes, I drove it to the gas station, filled it up and drove it for about 15 miles before I parked it in the driveway. It seemed to stumble, spit and sputter a little on occasion which it has not done in the past. It stalled as it has in the past, in fact a little more so at first than usual. Once it was warmed up, about 15 minutes it seemed to be fine, maybe even running better and idling better. Although I'm not sure.

 

At first I thought it was worst and that I'd drive it home, order the A/F O2 Sensor and hopefully install it next week, only driving it to my class which is about 25 miles away. Then I thought that maybe it needs to clear itself. At this point I'm not sure what to do. With this being said I haven't been able to check my gas mileage with the new FPR. I think maybe order the A/F O2 Sensor and don't drive the car until my class, install the A/F O2 Sensor and hope for the best. Any thoughts?

 

Another thing I forgot to mention was that when we checked the fuel pressure readings on 10/20/10 I replaced the fuel filter with a OEM one. It didn't make a difference but thought I'd mention it.

 

As always and as we continue. Thanks.

 

2000 Legacy

[OB99W]

With a new FPR, the fuel pressure should be within specs. With the ECU reset, if the A/F sensor was responding well, the engine shouldn't run worse than it did previously. The poorer running is likely another indication that the A/F sensor should be replaced. Even with a sluggish A/F sensor, there will eventually be some adaptation to the new fuel pressure (fuel trims will change), but that's not a good reason to leave the old sensor in place. If you get the chance, it would be interesting to see what the STFT and LTFT are currently. A single live data reading, once the engine is warm, should be enough.

 

There's another "chicken or egg" situation to consider. We checked the knock sensor and timing belt taughtness because ignition timing was erratic. Misfiring can cause that, but conversely problems with sensors can cause timing to be erratic and trigger misfiring. You could look at the crank and cam sensors, and get a basic look at the condition of the reluctors on the crank sprocket. First, check that the sensors (and mounting bracket for the cam one) are not loosely mounted -- spec is about 5 ft-lb. Then, remove each and make sure that the tip is clean. Look down the hole at the crank, and see if the reluctors seem rusty. R&R details are in the Fuel Injection section of the manual.

 

I sense that you're becoming somewhat disheartened. I think I've said this before, but since there are no codes other than the misfire ones, the problem is subtle and not easy to pin down. A car with over 200k miles on it can have several sensors, etc., that are somewhat out of spec, but aren't bad enough to trigger codes. It may well be that the problem is due to some combination of marginal parts. The ECU does a good job of correcting for irregularities, and while it keeps the engine running with them, it also "obscures" some of the faults. We've ruled out several possible causes, and you've replaced a few parts that were determined to be bad. I'm hopeful that the last piece of this puzzle is near.