Replace clutch - Now engine stumbles

[Mikevan10]

As noted in other threads, I replaced the clutch in my wife's 1997 Legacy (EJ22, non-turbo) over this weekend. The clutch had been juddering. New Exedy clutch and resurfaced flywheel and the clutch operation is now perfect. HOWEVER, when I test drove it, the engine started perfectly normally and ran perfectly normally for about the first 5 or 10 minutes. Then, all of a sudden, it stumbled pretty badly for a few seconds and then ran fine again. It does this on a seemingly random basis. Like I can drive for a few minutes at a time during which it operates perfectly normally and then it will suddenly stumble for,say, 3 to 5 seconds and then "catch" and run fine again. When I say "stumble" I mean it loses pretty much all power, although it does not actually stall.

 

I am assuming this must be an electrical problem since it is intermittant. I would think that a loose vacuum hose or an intake air leak or something would cause a consistent problem (although I did go back and check all the hoses anyway).

 

I checked and rechecked the two catalytic converter plugs, the speed feedback connection and the mass air flow sensor connector. These are the only things I can think of that were disturbed during the clutch job that have anything to do with engine operation.

 

Very frustrated. Clutch job went well but is always alot of work. Only to finish up and still not have a sound car.

 

As always, grateful for any ideas!

 

Thanks,

Mike V.

[ivans imports]

check main engine harness plugs dident get pulled slightly apart or loose grounds or disturbed a plug wire or dirty coilpack or your actualy geting the power to ground now more load on engine mabee problem is just more apparent now

[Mikevan10]

Thanks Ivan.

 

I have already checked and rechecked all harness plugs. The coilpack was not touched during the clutch job so I don't know why it would pick this moment to start acting up. I assume cleaning the coilpack would mean cleaning the high tension wire connections?

 

Definitely not a case of getting "more power to the ground" making it more noticeable. First off, the old clutch did not slip. It just juddered when pulling out from a stop. Secondly, this is a very definite loss of power that definitely was not there prior to this weekend.

 

Thanks again.

Mike

[1 Lucky Texan]

did you coincidentally get 'bad' gas? Maybe throw some HEET in the tank.

 

any CEL codes?

[Mikevan10]

L.T.,

 

The same tank of gas was in the car last wek, prior to the clutch job. Did not throw ANYTHING in the gas tank.

 

And, no, the MIL (aka CEL) is not illuminated. I forgot to mention that before. It comes on when I turn on the ignition but extinguishes immediately upon engaging the starter. This also aggravates me. In the past I have had not been able to pass state inspection because the CEL was on and the car was running fine. Now I have operational problems and no CEL! Gotta love it.

[Gloyale]

check all the PCV hoses and the IAC hose connections to the air intake.

 

Check the MAF clamp too.

[Mikevan10]

Hi Gloyale,

 

Yep, I chacked all of the hose coonections, including the MAF sensor. No detectable issues there. Besides, as I mentioned above, don't you think if there were an air leak somewhere, the problem would be continuous, not intermittant?

 

Mike

[1 Lucky Texan]

surprisingly, I've read lately of MAF problems not throwing a code - but yeah, it seems unlikely it'd be this intermittent. But moving old hoses around might lead to a cracked one somewhere - maybe sensitive to 'flex'. You might let the engine idle and try pushing/pulling on wire and hose bundles, in an attempt to replicate the problem. maybe a ground was disturbed?

 

you could T a vacuum gauge into it, run it into the cabin to monitor when the engine misbehaves. Might help with diagnosis, maybe just confusing though as I'd expect a stumbling engine might have weird vacuum anyway. Someone else here might have some insight on that.

 

maybe try an ECU reset.

Edited May 7, 2012 by 1 Lucky Texan

[Mikevan10]

OK, I will see if I can get it to misbehave by, with the car sitting idling, tugging on wires and hoses.

 

In the meantime, do I understand correctly that the rear oxygen sensor has absolutely nothing to do with how the engine runs? Is it only there to monitor how well the catalytic converter is performing and if the cat is not doing its job, then I will get a CEL code (by virtue of the rear oxygen sensor)?

 

On the other hand, I would guess that the front oxygen sensor has alot to do with how well the engine runs, correct? If so, would it be typical to have intermittant stubling if there was a fault with the front oxygen sensor circuit? And this would not set an error code?

 

Any other ideas out there?

 

Mike V.

[1 Lucky Texan]

AFAIK, rear sensor just tests cat conv efficiency.

 

Front O2 is used to adjust A/F ratio. Might be interesting to see what the long and short term fuel trims are set at. My scanner will only read that if I have a CEL on though - maybe someone here knows a way to retrieve that info.

 

what's the mileage/condition of the car? Any other work done during the clutch work? Or right before?

 

crank angle sensor could be intermittent, knock sensor, some similarity to a bad engine temp sensor and those often won't set a CEL.

Edited May 8, 2012 by 1 Lucky Texan

[Mikevan10]

Car has about 245,000 miles on it. No other work was done on the car while we replaced the clutch over the weekend. No other work has been done on the car over the last couple of months. There was no indication of any stumbling or other engine operational issues prior to this weekend. I am very reluctant to believe that, just by coincidence, some component began malfunctioning right at this time.

 

Thanks again. Please keep the suggestions coming!

[1 Lucky Texan]

is it possible a vapor/vacuum line to the canister/tank purge system was pinched or knocked loose?

 

 

You might use an OBDII scanner to see if any codes are pending.

[aircraft engineer]

Is your stumble at speed and then just a simple miss or is it pronounced - longer duration and then just disappears? Have you cleaned the MAF? My stumbling was pronounced - even an occasional on the cruise control at about 60 - on the cruise you really notice a M IS S.

 

Then it got nasty so I cleaned the MAF and it quit - only to recur on a 30 mile drive home from Seattle (2 days later - almost all freeway). I was lucky - my sister has the same car so I borrowed a different MAF (all 2.2 use the same unit - mine is a 97 2.2 Imp) and it disappeared just like it had never happened.

 

A trip to the salvage parts facility for another and the problem is gone. It sounds just like my problem - you might be able to get by with the CRC cleaner. If not, then there's replacing the MAF - worked for me. It's nice to be able to trouble shoot with a known good PART.

[Mikevan10]

The stumble is quite pronounced. You can be cruising along just fine and suddenly you lose, basically, all power. The car will, oviously, immediately slows down and makes you think it is going to completely die, then, suddenly, the power comes back and the car lurches forward and resumes running properly. It will repeat this anywhere from a few seconds to, say, 20 seconds later. It has never actually stalled. It will sit and idle without issue.

 

Yes, I did clean the MAF sensor with the CRC proprietary cleaner. No help.

 

I still am reluctant to believe this is just a coincidental component failure. I believe it has to be something related to the clutch job.

 

I do have two 1992 Legacy's so I could swap in another MAF if no other solution shows up.

 

It was raining last night and I do my work outside in the driveway so I did nothing last night. If it is not raining toninght (it is supposed to...) I will once again recheck all of the wires and hoses that were, or could have been, touched in the course of the clutch replacement.

 

I will also borrow an OBDII scanner an see if that tells me anything. Like I said the MIL/CEL is not illuminated.

 

Keep the ideas coming!

 

Mike V.

[Fairtax4me]

When you lose power no lights on the dash come on?

[Mikevan10]

All test driving has been during daylight but, no, I have not noticed any dash lights coming on.

 

Are you referring specifically to the MIL?

[1 Lucky Texan]

wait, does this car have a clutch or 'neutral' safety switch of some kind? could that cut the ignition?

[Mikevan10]

There is a switch that prevents the starter motor from operating unless the clutch pedal is fully depressed. As far as I know it ONLY effects the starter motor, but I do not know for sure.

[Mikevan10]

And according to the wiring diagram, there is a Neutral Position Switch.

[Fairtax4me]

NSS only affects starting, has no effect on an already running engine.

 

Trying to determine if the engine is actually stalling due to an electrical/sensor issue. Generally if the car is still rolling in gear the engine will continue turning so everything still works. Assuming the CEL actually works (it should turn on with key ON, then go out after a few seconds), it wil come on if the engine stalls, the battery light should come on as well.

 

Generally a loss of all power means the engine is no longer running, fuel and or spark have been cut completely, if the transmission is still in gear and the car is rolling, the engine is still spinning because of mechanical force, but not on it's own power.

Next time it does it hold the clutch down, see what the tachometer does. If it drops straight to 0 it's because the engine has stalled. You'll get an oil pressure light, a battery light, and hopefully a CEL.

[Mikevan10]

If I follow your drift, you are suggesting that maybe the engine is, in fact, stalling and continues, of course, to rotate since the transmission is in gear and the clutch is engaged. Then, for whatever reason, the presumed electrical/sesor issue resolves itself and since the engine is already turning, it starts to actually "run" again? Is that what you are thinking?

 

I will depress the clutch next time it stubles and see what happens. Unfortunately this is a Brighton so it does not have a tachometer.

 

And yes, the CEL does come on when you trn the key on and goes off as soon as you start the engine.

 

Thanks again!

[Mikevan10]

Update: Last evening I went out (in the rain) and started her up and let it idle for about ten minutes. Operated normally. The CEL illiminated when I turned on the ignition and extinguished as soon as the engine started (i.e. right away). After lt had warmed up I went around tugging and pushing around wires and hoses all over the engine compartment. No reaction. She just kept purring. So I decided to take a test drive and see if she would stumble at which point I was going to depress the clutch pedal and see if it would stall or if any lights came on or anything. Well, she never stumbled (sounds like a Bob Dylan song) HOWEVER, the CEL (MIL) suddenly came on! I continued driving for a few more miles but she never did stumble. The CEL, of course, remained illuminated.

 

This is the first time I was ever actually glad to see the CEL. I am hoping that the fault code(s) will clue me in on the problem. I have to borrow a scanner and it may not be until Friday that I'll be able to check it out. Will advise.

 

Mike V.

[Mikevan10]

With the "CEL" illuminated, I drove the car to the AutoZone which is about 10 miles from my house. The engine was stumbling badly and I was worried that it would die on me. But is never did. Incidently, I tried depressing the cliutch when it stumbled but it would not stall or anything. Anyway, I had the OBDII codes read. There was only one code: P0130 which is oxygen sensor related. So I went ahead and bought a new front Bosch "OEM" sensor. They hit me 100 bucks for it. They also offered a Bosch "universal" sensor for about 60 bucks.

 

I installed the new front oxygen sensor and took a short, 5 mile or so, test drive. No stumbling! I am hoping that the oxygen sensor was the problem but will not be confident until we get some more time and miles on it.

 

I still do not believe this was a coincindence. I am thinking that when I dropped the exhaust system with the oxygen sensors still connected, that even though the fron sesor unplgged itself, it was somehow damaged.

 

Thanks again for everyone's comments! Now I am trying to decide whether or not to replace the clutch in my '92 this weekend...

 

Mike V.

[hohieu]

I'm glad you figured it out and that the "CEL" pointed you in the right direction. Maybe the wiring was damaged somehow and removing it was the last straw.

 

Silicone will also poison O2 sensors. Any reason you were spraying silicone around while things were apart?

[Mikevan10]

No, I wasn't using any silicone.

 

I forgot to mention, I masured the resistance of the oxygen sensor heater (white wires) and it showed a closed circuit (0 ohms). The Haynes manual says this should measure 20 or 30 ohms (cannot remember exactly). I don't know what this indicates.