2000 Legacy stalls when clutch is depressed

[2000 Legacy]

Hi everyone,

 

I just replied to 987687's problem, Weird VSS" and was wondering if thats what my problem is. I know that someone had mentioed it in an earlier response but brushed it off since the speedometer seems to work fine and since the only trouble codes I get are for Cylinder Misfires.

 

Thanks for everything everyone in trying to help me solve this problem.

 

2000 Legacy in CT

[Fairtax4me]

So I read at some point here that the IAC motor was replaced. Did they replace the entire unit or just the electronic actuator on top?

 

What about vacuum hoses? Have they all been thoroughly checked?

 

And it shouldn't have anything to do with the problem when the engine is cold, but was that O2 sensor ever replaced?

[2000 Legacy]

Hi Fairtax4me,

 

Thanks for responding again.

 

It was the Dealer that replaced the IAC motor, they were going to charge me $250.00 to do so. At that price I would think that it would be the entire unit. It was the second thing they did after replacing the remainder Fuel Injectors. Neither worked so I had them put the old parts (Injectors & IAC)back in.

 

DaveT and I checked the vacuum hoses on 3/29/10 (post #19) and things seemed to be ok. This past Sunday night I was poking around and noticed on the under side of the hood a diagram of the vacuum system and traced the hoses, I think that there were 4 or 6. I didn't see anything that looked abnormal. Now when we checked on 3/29 we connected the guage to just the intake and not all of them. The reading we got was 16-17. Should we have done all of them or was just the one good enough?

 

The O2 Sensor was never replaced. I keep wondering if that could be the problem as well. I just cleared the codes two times about 25,000 miles ago.

 

Thanks again

2000 Legacy in CT

[OB99W]

2000 Legacy, did you ever verify the correct operation of the neutral switch? While this may not be the source of your problems, it can absolutely cause the symptoms you are experiencing.

[Trevor]

Just throwing this out there, but could it be fuel delivery?

[2000 Legacy]

Hi OB99W and Trevor,

 

I have never verified the correct operation of the "Neutral Switch", I don't know how to do that or what to look for. I did notice this past winter when I had the car on jack stands to do the front drive axles that the plastic nut (I think) was loose on the Neutral Switch so I snugged it up. If I remember correctly it was a small wire connected to the plastic nut. I wasn't too sure about it and it seemed complicated at the time. Please let me know what I can do to verify the correct operation.

 

As for the "Fuel Delivery", I had replaced the fuel filter that I got from NAPA at about 176,000 miles (I think, it's documented early on). I'm not sure but it almost seems thats when the problems started and have often wondered about changing the fuel filter again. However it seems to me that if the filter was bad that the car would spit and sputter all the time. The car runs great with exception to a rough idle until you come to a stop or intersection when the clutch is pushed in.

 

Thanks

2000 Legacy

[OB99W]

I have never verified the correct operation of the "Neutral Switch", I don't know how to do that or what to look for. [...]

The best place to check (best because the entire neutral position switch circuit can be tested, not because it's the easiest to get to) is at the ECU. Disconnect the car battery (to minimize a possible accidental short, etc.), and connect an ohmmeter between ECU connector B135 pin #26 and ground. The reading should change between high and low resistance as the shifter is moved each time between neutral and other gear positions. Move the shifter several times to verify that the switch contact is always reliable. See attachment for B135 pinout.

 

Let us know the resulting readings. Don't assume the switch is bad if you don't get expected results, as there could be wiring or connector problems.

[2000 Legacy]

Hi OB99W and anyone else that can possibly help,

 

I first checked the codes from the Check Engine Light (P0301, P0302, P0303 and P0304; Cylinder Misfires on all 4 cylinders). Disconnected the negative cable on the battery. Got to the ECU and checked Pin # 26 on ECU Connector B135. Note, your attachment looked like it was inverted, I happened to be looking at the 2000+_Legacy_FSM, sheet EN(H4)-38 which is what our car looked like. Also noted that there was nothing in Pins 22, 23, 24 and 25 on Connector B135. Anyways the readings we got on my cheap Ohmmeter was "0" in Neutral, then shifted into

1st gear it was about 26 to 5.9,then shifted into

2nd it was 38.4 to 0.6 then

3rd: 95 to 0.6 then

4th: 185 to 0.6 then

5th: 30.3 to 0.7

we repeated this two more times and the first number we got was different but it always seem to settle or end/drop to 0.6 except for 1st gear. The second time we checked it settled or dropped to 1.6 and the third time it settled or dropped to 0.7.

 

Now I have to admit as I am no mechanic, nor do I understand electric circuits or fully understand how to read my meter. I believe that I had it on the ohmms setting at the lowest number which was 200.

 

We then took the car out on a 10 mile ride and stalled at just about every stop. I also had th car going at about 50 mph, pushed in the clutch and the tachometer dropped real quick and start to shutdown, I'd take my foot off the clutch and the car would restart or pop start. I did this in every gear. Like I mentioned early on of this six page problem, it seems as the car is warmed up the stalling is less frequent.

 

Oh well, thanks for everything.

2000 Legacy

[OB99W]

Note, your attachment looked like it was inverted, I happened to be looking at the 2000+_Legacy_FSM, sheet EN(H4)-38 which is what our car looked like.

The attachment shows the B135 connector. The page you've referenced shows the pinout from the perspective of the mating connector on the ECU, hence the seeming inversion. It's likely you were on the correct pin, but just to be certain, there should be a black wire with green stripe at that pin.

 

From the readings you got, it seems that you back-probed pin #26 of B135 without disconnecting it from the ECU. (That could account for the changing readings, since it would be dependent on the electronics in the ECU.) Assuming I'm correct, please disconnect B135 from the ECU first, and then make the resistance checks again.

 

 

Also noted that there was nothing in Pins 22, 23, 24 and 25 on Connector B135.

That's interesting. Are you certain that there's no wire at pin #24 of B135? (The FSM indicates a green with black stripe there, coming from the VSS.)

[2000 Legacy]

Thanks OB99W,

 

I'm pretty sure that it was a black wire with a green stripe at Pin #26. When I retake the readings I'll double check. I pobally won't get to it until this coming weekend.

 

You are correct, I "back probed" Pin #26 with the wire still plugged into the connector. From what I understand, I'm going to disconnect the B135 Connector from the ECU completely and measure the resistance from the B135 Connector, Pin #26 (Wire side, not on the ECU itself. Am I correct in saying that?) and a ground. I used the ECU mounting bracket as a ground last night. Is that OK?

 

I'll also double check Pin #24 on the B135 Connector.

 

Thanks for all you help.

2000 Legacy

[OB99W]

From what I understand, I'm going to disconnect the B135 Connector from the ECU completely and measure the resistance from the B135 Connector, Pin #26 (Wire side, not on the ECU itself. Am I correct in saying that?) and a ground.

Yes, measure from B135 pin #26 (wire harness) to ground.

 

 

I used the ECU mounting bracket as a ground last night. Is that OK?

Any chassis ground will do.

 

 

Thanks for all you help.

2000 Legacy

You're welcome. I think we're nearing resolution of your problem, but lets wait to see what you measure before I comment further.

[2000 Legacy]

Hi OB99W and to anyone else interested,

 

My son and I took new ohmm readings from the ECU, B135, Pin #26 (wire harness) and to a ground. We used the bracket that the ECU mounts to for the ground. Our readings were similar to when we back-probed it the other day, at least the second number anyway. It almost always ended in 0.6 Ohmms, a few 0.7's and 0.8's. Note, I set the meter to 200, the lowest setting for Ohmms. The first number was as follows:

 

First Run Second Run Third Run Fourth Run Fifth Run

in 1st: 36.2 5.1 4.6 3.6 25.8

in 2nd: 45.0 39.0 ??.? ??.? 80.1

in 3rd: 52.0 14.8 16.7 85.0 22.0

in 4th: 40.0 ??.? 17.6 53.0 115.0

in 5th: 23.7 95.3 26.7 21.0 90.0

 

Thinking about it afterwards I asked my son who did the shifting and documenting if he took his foot off the clutch once it was in gear while doing the numbers, he said no that he left the clutch in the whole time while in gear. He took it off while in neutral. So I'm not sure if that makes a difference. We left everything unplugged and disconnected in case we need to redo it or check anything else at the ECU. Also you were correct, Pin #26 at B135 was a Black wire with a Green stripe.

 

We also double checked, Pin #24 on B135 was there as a Green wire with a Black stripe. Again you were right.

 

Thanks again for everything, I really appreciate your efforts as well as everyone else who has tried to help.

 

2000 Legacy

[OB99W]

Hi OB99W and to anyone else interested,

 

My son and I took new ohmm readings from the ECU, B135, Pin #26 (wire harness) and to a ground. We used the bracket that the ECU mounts to for the ground. Our readings were similar to when we back-probed it the other day, at least the second number anyway. It almost always ended in 0.6 Ohmms, a few 0.7's and 0.8's. Note, I set the meter to 200, the lowest setting for Ohmms. The first number was as follows:

 

First Run Second Run Third Run Fourth Run Fifth Run

in 1st: 36.2 5.1 4.6 3.6 25.8

in 2nd: 45.0 39.0 ??.? ??.? 80.1

in 3rd: 52.0 14.8 16.7 85.0 22.0

in 4th: 40.0 ??.? 17.6 53.0 115.0

in 5th: 23.7 95.3 26.7 21.0 90.0

Something seems to be amiss with the neutral switch, but the ohmmeter readings aren't making it obvious.

Also, a reading in neutral as well as in gear would be helpful.

 

Let's try a slightly different approach, using voltage rather than resistance.

1) Reconnect B135 to the ECU.

2) Reconnect the battery.

3) Set your meter to an appropriate voltage range to measure 12 volts or less (20 volts?).

4) Turn the ignition "ON", but don't start the engine.

5) Backprobe B135 pin #26, and record the voltage with respect to ground in both neutral and the gears -- two runs is sufficient.

 

Let us know what you find, although I'm suspicious that things won't be normal.

[2000 Legacy]

Hi again OB99W,

 

The ohmm reading that we get in while in Neutral is "0", there is a "1" to maybe 5 digits to the left, I just assume that was zero since there are no digits to the right. Do you think we should take ohmm readings in each gear with the clutch out?

 

Could I not be reading or using my meter correctly? The other thing I forgot to mention was that when I measured the resistance earlier today I wondered if I shouldn't have taped a paper clip to the probe on the meter since it didn't go into the B135 connector too far, but I was getting something and figured I was good.

 

Also, the other night I was looking at the Haynes book. It mentioned going to the actual switch and following the wire and taking a readiing where it connects. If I remember correctly. I'm not sure I fully understand it and would have to read a little closer but I'm willing to do it if it helps. Of course I'd have to jack up the car and put it on stands.

 

I just checked my meter, I will set the "DCV" to "20", follow your instructions above and let you know what I get. I guess it will have to be in the morning. Thanks again

 

2000 Legacy

 

2000 Legacy

[OB99W]

I just checked my meter, I will set the "DCV" to "20", follow your instructions above and let you know what I get. I guess it will have to be in the morning. Thanks again

You're welcome. Let's get the voltage test results, since they might be easier to interpret, before digging in any further.

[2000 Legacy]

Thanks OB99W, I'll get the results and post them first thing in the morning. Goodnight.

[2000 Legacy]

Good morning,

 

I took the voltage readings as you mentioned; reconnected the ECU & negative battery, set my meter to DCV @ 20, turned on the ignition (without starting) and backprobed pin #26 on B135 two times and got the following results:

 

in Neutral: 11.11 the fisrt time and 11.14 the second time

in 1st, 2nd, 3rd, 4th & 5th gears it always ended with 0.01 both times

 

the first number (I'm not sure if it has meaning) inbetween shifting was anywheres from around 6, 2, 9, 2, & 6 respectively.

 

Thanks

2000 Legacy

[OB99W]

Thanks for taking the voltage readings. The result is good news/bad news. The good is that the voltages are correct, eliminating questions over the neutral position switch causing problems. The "bad" is that we need to look elsewhere.

 

(I'm apparently getting obsessed with this -- I just reread the entire thread, and took notes this time!)

 

Back to basics -- declutching is resulting in a stall. It's been determined that this model has no clutch switch other than the one used for starter interlock, meaning that the ECU isn't informed of the clutch position. So, what could be happening? I see some possibilities:

 

In typical street driving, people generally get off the throttle just preceding declutching. If the engine isn't running correctly, the transition towards idle conditions might not be smooth. Also, the clutch assembly has some mass, which when disengaged no longer aids the flywheel. The ECU could detect more misfires, etc., and might not be able to compensate for them as readily.

 

As has been mentioned previously, the intake vacuum reading (16-17 inches, varying) is too low for your location (Colchester apparently has an elevation of about 500 feet above sea level, which would only drop vacuum from typical by about 1/2"). Your reading seems to be a couple inches below where it should be. There are several things that can cause low vacuum. Since leakage is a primary one, it's probably good to start there. A bad diaphragm in the brake booster is one potential cause. You can check this in various ways, but the most direct is to disconnect the hose at the intake manifold, and plug the port. If there was a leak in the booster or hose, the vacuum will come up and the idle will get smoother.

 

Vacuum leaks can often be heard as a hissing sound. A piece of hose used as a stethoscope, with one end held to an ear and the other near potential leak sites (intake gasket, etc.), can help pinpoint them. Also, some intake cleaner sprayed at suspect areas with the engine idling will cause a change in idle if you hit a leak.

 

I've assumed (perhaps without merit ) that things previously checked and/or replaced are not the cause of the problem. One thing that I didn't see mentioned in this thread is the intake air temperature sensor.

Has it been checked or replaced? A bad IATS can report to the ECU that the air temp is higher than it is, affecting A/F ratio, especially on a cold engine.

 

A scan tool (or computer with appropriate software) used in real time (live) and looking to see if sensor data makes sense (air temp not saying, for example, 110 degrees when the car's cold at 60 degrees). If possible, verify that all such data (ECTS, even though it was replaced) is "in the ball park". If you do run a scan and have questions about the results, let us know.

[2000 Legacy]

HI OB99W,

 

Thanks for the effort, I really appreciate all your time. I don't mean to give you something to obsess over. I'm a little disappointed, I was hoping that it was the Neutral Safety Switch or the VSS. Oh well the saga continues. Let me look over and reread your response to see if I can understand it better. As I mentioned before I am not a mechanic so some of it is greek to me. I'm sure I'll have questions. I'll try to post something during the week, it will probally be later on. Thanks again.

 

2000 Legacy

[Mr. Carb]

I'm betting it's the fuel pump, if it fails like mine did, that's more than likely your problem. They typically fail by cracking or popping the cap off of the bottom of the pressurized section of the fuel pump, thus leaking gas pressure back into the gas tank.

 

Also, that Air control valve, and clutch switch could be another thing to start looking at. My 2001 always changes idle speeds based on being in neutral and whether or not the clutch is depressed, especially when cold.

 

You can see in this picture the part that failed on my fuel pump, notice the small piece of O-ring sticking out?

 

I hope that helps.

[OB99W]

I'm betting it's the fuel pump, if it fails like mine did, that's more than likely your problem. They typically fail by cracking or popping the cap off of the bottom of the pressurized section of the fuel pump, thus leaking gas pressure back into the gas tank.

It wouldn't hurt to measure fuel pressure and delivery, although it seems a bit counterintuitive for a failing pump to show more symptoms at lower speeds (when the fuel demand is less) than at higher loads.

[2000 Legacy]

Hi OB99W,

 

I had a chance to re-read your response, thanks for taking the time to do so. In doing so I tried to understand everything.

 

Intake Vacuum Reading:

1. What should it be?

Legacy 777 said 19 on 3/30/10.

2. In checking the diaphragm on the brake booster, do I disconnect the hose at the intake manifold, plug it with tape and leave the hose connected at the brake booster and let it hang, then start the car and let it idle?

When we had checked the vacuum reading back in March I believe that we checked it at the throttle body, was that correct or should we have used the intake/brake booster?

 

Intake Air Temperature Sensor:

1. It hasn’t been changed or checked as far as I know.

 

Scan Tool (or computer with appropriate software) used in real time (live):

1. Is there a place where I can rent one or how expensive are they? I tried Advanced Auto and they said that they have the Actron OBII code reader.

2. How does it work? I imagine that it plugs into the OBII port.

3. How long does it take to do (time wise) or how many miles do you need to drive to capture the necessary data?

4. Will it give the history/details on everything (all sensors)?

5. What are we looking for;

a. Engine Coolant Temperature Sensor?

b. Intake Air Temperature Sensor?

c. Would it tell us of any Vacuum Leaks?

 

Anther thought:

In trying to understand everything I was poking around the 2000 FSM and found on page “EN(H4)-144”, DTC P0133 where it said “DTC Detecting Condition: Two consecutive cycles with fault”. Could this be the problem (front O2 Sensor)? In reviewing my history I noticed that I had this code, P0133 two times, once on 1/29/08 with 172,929 miles and on 5/7/08 with 178,225 miles. I cleared the code both times and haven’t seen it since. On 3/19/08 at 176,020 miles I replaced the Muffler Pipe and Mid Pipe.

 

Again, thanks for everything

 

Mr. Carb,

 

Thanks for chiming in; I’ll add your suggestions to the list of things to check. I didn’t see the picture of the part that failed on your fuel pump.

 

2000 Legacy

[OB99W]

Hi OB99W,

 

I had a chance to re-read your response, thanks for taking the time to do so. In doing so I tried to understand everything.

 

Intake Vacuum Reading:

1. What should it be?

Legacy 777 said 19 on 3/30/10.

If the engine is healthy and warm, at an altitude not much above sea level the intake vacuum should be about 19 inches (or even a bit higher) at idle.

 

 

2. In checking the diaphragm on the brake booster, do I disconnect the hose at the intake manifold, plug it with tape and leave the hose connected at the brake booster and let it hang, then start the car and let it idle?

When we had checked the vacuum reading back in March I believe that we checked it at the throttle body, was that correct or should we have used the intake/brake booster?

Start the engine and allow it to reach warm operating temperature. Connect the vacuum gauge as you did before (throttle body), and take a reference measurement. Yes, disconnect the brake booster hose at the intake manifold (which if you do so with the engine running might cause it to stall), and close off the port at the intake (with tape or rubber plug, etc.). Start/restart the engine, and take another vacuum reading. If there's an improvement, the brake booster is leaking. If there's no change, that eliminates a possible leakage point.

 

 

Intake Air Temperature Sensor:

1. It hasn’t been changed or checked as far as I know.

They do sometimes fail, so the data it's sending to the ECU should be checked.

 

 

Scan Tool (or computer with appropriate software) used in real time (live):

1. Is there a place where I can rent one or how expensive are they? I tried Advanced Auto and they said that they have the Actron OBII code reader.

Can DaveT help? I don't know the Actron line well enough (especially without a model number) to know whether it would be appropriate. Typically a "code reader" doesn't do much more than reveal stored OBD-II DTC codes, while a "scan tool" can read real-time ("live", as it occurs) data. I personally use an Innova Equus scan tool. You should of course verify that any scan tool you're considering will retrieve the necessary data.

 

 

2. How does it work? I imagine that it plugs into the OBII port.

Exactly.

 

 

3. How long does it take to do (time wise) or how many miles do you need to drive to capture the necessary data?

Real-time data is nearly instantaneous. The time to trigger and store DTCs, freeze-frame data and the like depends on how long it takes for the problem to occur. The drive cycle requirement for a particular code will determine whether it will be seen as history or pending. (See answer to #4 for some more.)

 

 

4. Will it give the history/details on everything (all sensors)?

Depending on the model, it should reveal stored codes, pending codes (ones where the problem is detected, but an insufficient number of cycles have been completed yet for the CEL to be lit), freeze-frame data (what sensors were indicating when a DTC is triggered), I/M monitor status, etc.

 

 

5. What are we looking for;

a. Engine Coolant Temperature Sensor?

b. Intake Air Temperature Sensor?

c. Would it tell us of any Vacuum Leaks?

For (a) and (, a decent scan tool should read them in real time. There is no direct indicator of vacuum leaks, although they can be inferred to a degree from other data.

 

We could be looking for other sensor data, depending on where the diagnostic path leads. (If we knew for sure where we were going, we'd probably be there already. )

 

 

Anther thought:

In trying to understand everything I was poking around the 2000 FSM and found on page “EN(H4)-144”, DTC P0133 where it said “DTC Detecting Condition: Two consecutive cycles with fault”. Could this be the problem (front O2 Sensor)? In reviewing my history I noticed that I had this code, P0133 two times, once on 1/29/08 with 172,929 miles and on 5/7/08 with 178,225 miles. I cleared the code both times and haven’t seen it since. On 3/19/08 at 176,020 miles I replaced the Muffler Pipe and Mid Pipe.

To quote myself from post #32 of this thread:

"The P0133 O2 sensor code is usually a reliable indicator of a failing sensor. The only other thing that could likely trigger that code is an exhaust system leak before (upstream of) the sensor. If there isn't such a leak, the sensor is probably bad. While it may not be related to the current problem, if the front (upstream) sensor hasn't been replaced within some reasonable number of miles, it probably should."

 

I still feel the same way. The ECU runs "open loop" (using default values and not looking at some sensors) until the engine and exhaust system have reached a certain minimum temperature. So, if the car has drivability problems that occur when the engine is cold, they shouldn't be related to the condition of the O2 sensor. However, O2 sensor data is obviously used once things warm enough, so a bad one could contribute to problems after warmup.

 

Again, thanks for everything

You're welcome. I hope the above clarifies some things.

[Mr. Carb]

Fuel injection acts a lot differently on fuel flow issues as I found out the hard way. My outback anyway struggled at the lower rpm and torque and acted normal otherwise when the pressure was dropping and the filter was plugged.

[OB99W]

Fuel injection acts a lot differently on fuel flow issues as I found out the hard way. My outback anyway struggled at the lower rpm and torque and acted normal otherwise when the pressure was dropping and the filter was plugged.

Based on your experience Mr. Carb, it would seem Legacy2000 should consider investigating the possibility.

 

I snipped a bit of Mr. Carb's fuel pump picture and circled the piece of protruding O-ring. Compare to the original picture to better visualize.