My car is mad at me! Random stalling, rough idle

[macadamianut]

I think my car is mad at me,

I'm experiencing random stalling and a rough idle. I read the how-to document on cleaning the MAF and thought it was my problem. On the highway, the car would occasionally stall for about a second and then pick up again. But, after cleaning the MAF, nothing has changed for better (or for worse -thankfully.) It had been occasionally idling rough for awhile now but never stalled before recently.

When the car is neutral/park, any rpm will produce a random shudder or miss type of feeling. Could it be a dying MAF sensor? What is the stage in the ignition before it goes to the coils on the plugs? Check grounds? Fuel pump? Relay? I don't know where to start.

I have recently replaced spark plugs (Bosch iridium/platinum), pcv valve, air filter, fuel filter and have run STP fuel system treatment through. Replaced alternator, new timing belt, fixed popped-out rear axle, etc. See what I mean? Is this a case of "give her some attention and she'll always want more?"

Thanks for any insight,
Mac

[SoCal LS-L]

Sounds like a classic misfire. You may have caused a vacuum leak when you did the PCV valve, or you might have disturbed the wiring to one of your coils enough to cause a random misfire.

[macadamianut]

I replaced plugs, pcv valve, fuel and air filter in hopes of correcting the rough idle. So they were all done after the rough idle about 6 months ago, but before the stalling which started about 2 weeks ago. Arrgh! I'm also NOT getting a check engine light at all. Would there still be trouble codes in the ECU if I took it to a dealer to have them read?

[trophy956]

hi i agree with the miss fire being your problem ,95 svx its not OBD 2?
the injectors have codes but only for elecrical failure ,the secondary ignition is not ,if you can get it to missfire in a stall test ,loosen the injector plugs and have someone sit in the car and stall test it and unplug them to find the cylinder which isnt working ,thats how i do it ,just stand off to the side when doing the test
charlie

[macadamianut]

Did the code test at lunch today with the blue wire into terminal 2 on the diagnostic port. CEL blinked constant to show NO fault codes. What??? How can this happen? Also for fun, I let the engine idle and disconnected the MAF. Engine immediately quit, (as expected.) Not sure if that helps with anything.

Aside from the random stalling- Holding idle at any rpm, the engine will shudder randomly (smooth for a second then a slight shudder then smooth again.) Almost seems like a very muffled backfire, a deep, airy, low toned poof - not a bang like a typical backfire. Could it maybe be a bad coil pack or a bad boot covering the plug that is arcing to the head? Why, if it was just one coil, would it cause the whole engine to shut down and with no CEL? Fuel delivery problem? Vacuum leak? Anyone local that would be willing to help? Anyone have an extra MAF I could use to rule that part out?

I have no idea how to do the stall test. Is the procedure listed somewhere?

Cornfused.
Mac

[Suby Fan]

ok some obvious things are air filter box not installed correctly or a vacuum leak... can you hear a whistling sound while the engine is idling? try junk yards for a MAF its allways good to have a back up even if it not the problem. i have 2 in my tool box and im not even driving a suby right now .... stall testing is just pressing on the brake and gas at the same time to load the engine down to get it to act up

[dumpstafresh]

i just posted a thread on a similar problem.
of corse i gets no help round here. but you have 5 replies. thanks guys.
i guess people arent on here as much as they used to be.

Anyway, It turned out to be the maf.
but his threw a maf code. (#23)

When you get on it does it stall completly then cut back on if you stay on the gas. (thats what would happen to my friends)
Or does it misfire. Thats more like a stuttering. One cylinder not fireing.
It should be easy to tell the difference. (unless svx's are programed to cut out all power when it misfires.)

but then again, you could just need to grease yer muffler bearings

[macadamianut]

Unfortunately, I am not getting any codes. If I let it idle in the driveway, once it reaches operating temp, it will start idling rough (like its on 5 cylinders) and then without any warning at all, completely shut down.

[wawazat??]

Some further background on the car, it has an ECUTune Stage1 v.5 in place from my time of ownership.

I had forgotten about a possible vacuum leak. The car is a 1995 (14 years old) and I doubt any of the vacuum lines under the intake have been replaced. Owner previous to me didn't put enough miles on to wrooy about them and I never had a problem (nor did I replace them) while I owned it but that may be the culprit Mac.

If all else fails, Hodges Subaru should be able to help solve the problem. Just get a flatbed to tow it to avoid possible transmission/differential problems.

Todd

[macadamianut]

Checked some things yesterday. All coils measure the same resistance. Pulled all injector wires one at a time with engine running and all are getting/spraying fuel. Got engine codes for injectors so it is saving something, just not what the actual problem is. Car is still somewhat driveable, just not reliable. Could stall when pulling out into traffic. It will run fine for awhile, then just suddenly quit. Will start right up and continue like nothing happened. This is so weird!

Mac

[Sean486]

I'm no mechanic (far from it ), but when I hear random stalling, followed by starting right back up and running fine. Well my personal experience tells me that is a bad MAF. Cleaning it usually is not enough, it probably needs to be replaced.

Do you live near anyone on the board? It would be good if you could temporily swap MAFs with them and see if the problem goes away, or if doesn't go away at least you can rule that out.

[macadamianut]

That's a good idea.

Does anyone around here have an extra MAF laying around that I could try for a couple days to rule that out?

I'm in Warren, MI

Thanks,
Mac

[macadamianut]

Picked up a used MAF today from a junkyard. Same issues no change for better or for worse. Now what, crank/cam sensor, temp sensor??? O2 Sensor?

[SURTEESS]

Check all your plug leads - mine when warm were pushing themselves apart when engine was hot (giving an under load misfire) - cured it by re-potting in hi-temperature silicon.

[Chip Hutchinson]

Howdy
You mentioned that one of the things you did was to replace the timing belt. I would bouble check that all the marks line up and that the tensioner is working.
Hope this helps.