intermittent idle surge with warm engine

[Micahgc]

I've tried serching for this, but i'm not even sure what to put in the search field;

 

I have a 93 Loyale EA82 5 speed. It runs great and seems to have normal power. However, when i stop when its warmed up, I stop in neutral (usually w/out the clutch pushed in once stopped) and the idle is around 12-1400 rpm. It fairly quickly switches down to ~1k rpm after I hear a click behind the dash (about the middle, seems like it comes from behind the clock in the dash). It sounds like a fan switch, but i dont know that could affect idle. I still can't tell for sure, but I think the surging only starts once i shift into first gear before taking off.. Pushing in the clutch doesn't make a difference, and nothing else i've tried has started the surging; when i put the clutch in and put it in first before taking off however, the idle surges up and down from about 900-1200 rpm while i'm stopped with my foot on the clutch. It doesn't hesitate or stall out (never has died) when i take off from the light, it just doesn't idle how it should. Also, once it starts surging, i can shift back to neutral and take my foot off the clutch, but the surge remains. It only goes away after I take off and stop somewhere else.

 

Also, it may be related, (I have no idea how) but i failed emmisions here in Oregon. The limit was like 250, i scored 350. If anyone is more familliar with this i'm probobly way off, i dont have the paper with me. I was over on both HC and CO, both by around 100 if i remember correct..

 

are these related? is there a sensor i should clean/check/replace? I keep reading about the TPS, though none of the threads i found sounded like what my car is doing.. It idles good until i shift into first, and i don't know what senser that might affect.

Edited March 1, 2010 by Micahgc

[Micahgc]

AND.. why does USMB not return any useful results for 'idle surge' until i post my thread? now they show up in the simmilar threads. I'm getting frustrated..

 

however, i still didn't find an answer. EGR valve?

[markjw]

Search "Idle air control valve"...Look for the cleaning and lube proceedure. That may be your problem.

[MilesFox]

soak the idle air control valve in Sea Foam. Just pour some in the breather tube and let it soak for about 15 minutes. usually the IAC gets carboned up and sticks open, when it should close once the car has warmed up.

[ihscout54]

When you first come to a stop the ECM will hold the idle a little high for a second or two. Then it should drop down to normal. If the engine is surging there should be some codes set. The fact that it starts when you put it into gear says the "nuetral switch" is working. There is a sensor that tells the ecm the car is in gear, the switch seems to be doing its job. I went through something similar in my car when I installed the F.I. It was being caused by the a/c system. For some reason the car would freak out and seek up and down when I engaged the nutral switch with the fan on in an a/c range. I disconnected the compressor and the problem stopped. I was getting a code for the idle control, so it sent me in the wrong direction totally.

I dont want to send you an a wild goose chase either, but after reading your post my mind went straight to a/c...

Do you have a/c, what position is your HVAC set to?

 

But first step, check for codes!

http://www.ultimatesubaru.org/forum/showthread.php?t=49918

[Micahgc]

Thanks for the tips on it, i will try cleaning the IACV tonight after work.

 

Its not sending any codes for the CEL, its never came on as long as i've had the car. I almost always have my HVAC on defrost, so my ac pump is running (i think..) however, i've tried it with the heater off, and the surge is the same. Heres a really dumb question, but does my 5 speed have a neutral switch? I didn't know that.

 

I read about cleaning the IACV that if you use something that leaves a residue it can stick-- Wouldn't sea foam leave a residue? Have you all tried cleaning with this, or should i stick to brake cleaner?

[The Dude Abides]

The way my motor was setup i just unbolted the throttlebody so i could access the IAC screws easier. Then when i removed it i cleaned up real good with Brake Cleaner. It did imprive things quite abit but not all. Someone had also mentioned the coolant temp sensor might of been coroded and check that as well.

[Micahgc]

I dont want to send you an a wild goose chase either, but after reading your post my mind went straight to a/c...

Do you have a/c, what position is your HVAC set to?

http://www.ultimatesubaru.org/forum/showthread.php?t=49918

 

I almost always have my defrost on, and hence the AC pump is running-- What did you end up finding with that? My car is factory FI (i'm not sure if its multi port or spfi) and factory.. well, everything. Is there another sensor involved that could cause the surging? So far IAC and TPS, anything else to check? also, could this be affecting my emmisions? I've had the car a little over a month and the CEL has never came on, so if i understand right, no codes will come up if i check-- right?

[ihscout54]

My car is factory FI (i'm not sure if its multi port or spfi) and factory.. well, everything.

Its prolly SPFI, one injector mounted ontop the intake. The boot should say "SUBARU F.I.". I converted my car to FI from carbureted, and had a number of lil bugs.

I almost always have my defrost on, and hence the AC pump is running-- What did you end up finding with that?

You might try disconecting the A/C switch, or pulling fuses and see if any eliminate this issue. For some reason my compressor didnt agree with the FI (best I can figure). My BRAT does not have a spot to install a "gear switch" So I put a switch on the clutch pedal to trick the ECM into thinking it was going in and out of gear so it wouldnt set a code. The switch is just a simple on/off in gear or nuetral. Its funny though my car did the exact same thing when the compressor was on. It was fine and idled perfect, just a lil high, then as soon as you pushed the clutch in it would seek (up and down up and down). I never drove it enough like this to say if there was more to it, once it set a code I was off till I found it was something to do with th A/C.

Is there another sensor involved that could cause the surging? So far IAC and TPS, anything else to check?

Your sure about the TPS, the idle setting may be out of adj or faulty. The MAF and temp sender may also cause a hunting condition, and they dont always throw codes. Is it possible someone messed with the idle stop screw? I also wonder if there isnt some kinda issue with the gear switch, bad contacts... Maybe you can unplug it. It will set a code after a while but that might stop the issue for now.

could this be affecting my emmisions?

Well yes, something is wrong, and just the simple up and down revving will waiste gas. It wont pass a smog check either.

so if i understand right, no codes will come up if i check-- right?

Just because it isnt catcing anything long enough to set the CEL, doesnt mean it hasnt caught something befor. There is a way to put it into a "self check" mode too. You might consider trying this. Edited March 3, 2010 by ihscout54

[ihscout54]

Do you have the factory service manual? Its full of testing info. Incase you dont here's a link to GD's online copy of the engine section. Its for an 89, but should be just fine to get you through.

http://home.comcast.net/~trilinear/SubaruEA82-ServiceManualPart2.zip

[Micahgc]

Thanks for all the info, that give me lots of places to look this weekend. I don't really think it has to do with my A/C, as it will do it whether its on or not-- It only happens once i put it in gear, and turning on the A/C or shutting it off once its happening doesn't stop it. The compressor makes a hit on the engine, so the surging slows for a few seconds, but it resumes as soon as the engine catches up with itself. Once it starts to surge, it wont stop until I've driven it a bit again and stop with it in neutral.

 

Also, I've only had the car about a month. I don't know how long its had any of these issues, i knew they were there when i got it. When i failed emmisions, the limits are:

H 200

C 1

 

I scored:

H ~300

C `3

 

From what i've read, this means its running rich (?).

 

I'll check the codes this weekend, I didn't think about them being in the memory. On my car, the connectors are on the engine side of the firewall, (I finally found them after searching under my dash for an hour) but I can only find a set of green connectors. From what i saw in the link, there should be green and black, and the black is what i need to connect to check history. Is this correct, or am I still confusing it with the later subies? I'll check again tonight, hopefully i can pull something.

 

As far as whats been adjusted, I have no idea. I put in a new clutch last weekend, but apart from that, i haven't changed anything. I didn't disconnect any sensors, i just pulled the engine forward. This issue happened before I replaced it, too, so i know i didn't change anything.

[hooziewhatsit]

The green ones under the hood are what you want to connect to read the codes.

 

The AC shouldn't have anything to do with the surging.

 

To remove the IAC, I've had luck breaking the bolts loose with vice grips. It's most likely sticking and causing your problem. Then clean it out and put it back on.

[ruparts]

Thanks for all the info, that give me lots of places to look this weekend. I don't really think it has to do with my A/C, as it will do it whether its on or not-- It only happens once i put it in gear, and turning on the A/C or shutting it off once its happening doesn't stop it. The compressor makes a hit on the engine, so the surging slows for a few seconds, but it resumes as soon as the engine catches up with itself. Once it starts to surge, it wont stop until I've driven it a bit again and stop with it in neutral.

 

Also, I've only had the car about a month. I don't know how long its had any of these issues, i knew they were there when i got it. When i failed emmisions, the limits are:

H 200

C 1

 

I scored:

H ~300

C `3

 

From what i've read, this means its running rich (?).

 

I'll check the codes this weekend, I didn't think about them being in the memory. On my car, the connectors are on the engine side of the firewall, (I finally found them after searching under my dash for an hour) but I can only find a set of green connectors. From what i saw in the link, there should be green and black, and the black is what i need to connect to check history. Is this correct, or am I still confusing it with the later subies? I'll check again tonight, hopefully i can pull something.

 

As far as whats been adjusted, I have no idea. I put in a new clutch last weekend, but apart from that, i haven't changed anything. I didn't disconnect any sensors, i just pulled the engine forward. This issue happened before I replaced it, too, so i know i didn't change anything.

 

 

HI,

I think you need to replace the oxygen sensor, at least do a voltage test to see if it in responding, should send a ("variable, back and forth")dc voltage signal of about .3 to .9 volt, that is a percentage of 1 volt, back and forth. this is with the engine at running temp. if it does not then its dead.

[Txakura]

wouldn't the oxygen sensor trip the 'check engine light', (CEL) if it were bad?

mine does with a loose wire, wiggle the wire, light goes out

 

or were you thinking it was not completly kaput, but out of spec?

 

I had the opposite problem with ea82 spfi, cleaned IAC which did nothing, it was the coolant temperature sensor, (CTS) telling the car it was already warm when it wasn't

 

running rich could be IAC, but CTS tells the ecm how to adjust the mixture doesn't it?

[Micahgc]

And for a strange development-- I'm starting to think my CEL was disabled, its NEVER came on, even when car is 'on' but not started. Subaru's show the light here, don't they? also, when i hooked up the green connectors under the dash, turned the key on, nothing blinked.. anywhere. The codes are supposed to display through the check engine light, correct?

 

The other trip is, as long as the green connectors are hooked up, it doesn't surge at idle.. in fact it idles about how its supposed to i'd think. Its about 1500 when i first stop, then gradually drops to around 1k. Why would having the diagnostics plugs hooked together affect its idle? It runs fine, doesn't seem to change anything but the idle. Is this normal/ok to have hooked up? more importantly, what might that be changing that makes it idle better?

 

As for the CEL, is it a process to disconnect? If they took the bulb out, will i have to pull the gauge cluster to replace it? any tips here would be very appreciated, I'm hoping i dont have to tear my whole dash out for some morons quick fix..

[ihscout54]

The light flashes through the LED on the ecu under the dash its self. The cel should come on when you have the key on eng off. If it doesnt theres an issue. The prev owners may have pulled the bulb to hide the problem CEL was trying to tell you. Having the green test connector puts the system into a test mode. The fuel pump cycles and some sensors are used differently. Perhapse it just ignores the function the gear switch serves. They are meant to be unplugged unless you are diag-ing. Did you read the last posts I left you including the link to the manual?

 

As for the CEL, is it a process to disconnect? If they took the bulb out, will i have to pull the gauge cluster to replace it? any tips here would be very appreciated, I'm hoping i dont have to tear my whole dash out for some morons quick fix..

Im not really sure on your car how easy it is to access the bulb, Im going to say you will have to yank the cluster to get to it. If they were in a hurry to get er sold and werent really that knowledgeable or didnt care theres no telling what was done to get the CEL to "go away". Someone will correct me if Im wrong. But check it first Key on engine off... Edited March 8, 2010 by ihscout54

[Micahgc]

Did you read the last posts I left you including the link to the manual?

 

snap, i'm in trouble

 

sorry, yes i did read it, i just must have misunderstood what light i was looking for. Thank you though for the help, i'll check it out at lunch today, see if its blinking at me. I looked under there and didn't see anything, but I'm sure it was because i didn't look in the right spot. When i read the link you posted (i promise i did, i even printed it out and had it in my car) I must have confused it with the other posts I'd read. Seems like every post has a slightly different method, though its probably just for different models.

 

I'll double check it, and good to know about the connectors. On my Loyale, then, the green connectors do both the running diagnostic and the display history codes? I'm assuming i must just have to connect them while the engine is off, than turn the key to 'on' and check the light on the ecu? also, really stupid question, but the ecu is under the dash, correct? ya.. my last car was a 64 nova, it doesn't quite have the same computer setup. As for my mechanical skills, well, i can replace parts like nobody's business.. I've just always worked on OLD cars.. so thanks for the patience

 

EDIT: you aint kidding, that link has a big ol section that says its gunna flash the codes on the ecu.. dont mind me

Edited March 8, 2010 by Micahgc

[ihscout54]

Im not being a "D", I just wanted to be sure you have the manual. Just incase you didnt download it. It will save your tail. It has a great section on reading codes. Thay can be a little confusing if you have never read them befor. Morris Code.... If you have codes, it will point us in the right direction and get you on the road the right way.

I'll double check it, and good to know about the connectors. On my Loyale, then, the green connectors do both the running diagnostic and the display history codes? I'm assuming i must just have to connect them while the engine is off, than turn the key to 'on' and check the light on the ecu? also, really stupid question, but the ecu is under the dash, correct? ya..

 

Yes, there is another set of connectors also, the manual and the USRM link describes these connectors and fuctions better than I can.

The ECU is under the steering column, you have to pull the plastickick panel 1st.

[Micahgc]

Coolbeans, i finally got the codes.. I had the 2 green connectors together, they must be for the running diagnostic. I plugged in 2 white connectors and it blinked my my codes I knew it would be simple, i just didn't have things hooked up right.

 

So, my codes are:

24- Air Control Valve or circuit

32- Oxygen sensor or circuit

34- EGR Solenoid or circuit

 

Good and bad new i suppose, at least now i know what the problems are. More stupid questions though, where is the air control valve? I searched for pictures and info, found lots of cleaning tips, but i still don't know what i'm looking for. Its the IAC valve correct? what does it do? I can pull it off and clean it, but i really don't know what to take off zzz. Is there one of these i should start with, or are they separate enough systems that they probably all need to be replaced/checked?

[ihscout54]

Do you have a digital volt meter? You must have one to properly diag this issue.

Good and bad new i suppose, at least now i know what the problems are. More stupid questions though, where is the air control valve?

I think you already cleaned this didnt you? Its on the front of the throttle body and has 2 - 5/8" black hoses: one on the bottom and one on the side. If you havent cleaned it then you need too, and replace the o-rings while your at it. There are great pics of it in the manual, and a locations guide too.

I will warn you though; that code is to be expected as the idle was malfunctioning. Just because you get a code doesnt mean its that part thats causing the issue. Odds are good that your O2 sensor code is related to what ever is causing the problem. Something is throwing off the ECM's abillity to controll the idle in all conditions. This ECM is fairly primitave it cannot tell you everything, but its not totally retarded either. So test befor you chuck.

You might go to the Junk Yard and get another IAC to clean and replace yours with to fully rule it out. *there is a test procedure in the manual too* . No supprise about the egr solenoid code, I doubt that has anything to do with this. But you do want to fix it.

Also did you confirm the CEL bulb was inop in the dash?

[Micahgc]

Ya, i do have a DVOM, but what am i checking with that? I should have cleaned the IACV by now, but havn't.. Its been a crazy week. I'm going to pull it off tonight and clean it out. And yes, the CEL isn't working for sure, i'll have to get a new bulb this week. Can the IAC throw the 02 sensor code? Or is it likely more than just one thing?

[Micahgc]

Well.. drawn out project but made some progress on it.

I've replaced the IAC valve with one from the junkyard, i pulled it open and cleaned it thoroughly with brake cleaner. I also pulled another EGR valve to replace mine, although I don't know how to test if this one is bad or not. Put both on, replaced the old vacuum line from the throttle body to the EGR, and took it through emissions; Failed worse than before. my HC went from ~300 to now around 500, and the other is still up around 3 when 1 is the limit. Looks like a pulled a bad EGR Valve, so i'm putting mine back on and rechecking the vacuum lines tonight after work. The idle is much more solid now, it very rarely fluctuates, and if it does it settles out on its own.

 

Also, the idle is about 1k-1200, which still seems high to me. My mileage went down as well. For a 93 4x4 Loyalle, what should i expect for mileage? I got 23-25 lately

 

I found on here how to test the IACV, CTS, 02 sensor, and maybe the EGR valve, although I don't know how to check it-- I will probobly swap on one from a toyota/honda.

 

Any other ideas? I have about 4 more days to get this through DEQ before my trip permit is up.

[brysawn]

I'm not sure if this was said or not. But on my loyale I also had a surging idle, it would go really high, then really low, and I would also hear that click noise. It was due to a vacuum leak from a bad intake manifold gasket, also this caused a injector and crankcase code. The gaskets were replaced, and the codes were cleared and I have yet to have them back (*knocks on wood*) and now it idles perfect.

Edited April 2, 2010 by brysawn