jsacrey

Have done the following this weekend:

Removed the negative battery cable for 2 days while work was happening
Adjusted the valve clearances
Changed the rotors and distributor caps
Changed the fuel filter
Cleaned the ISV
Tried to remove the oxygen sensor since it has 85,000 miles on it and it's mated to the catalytic converter. I think I possibly damaged it....tried removing with a torch by heating around it....

Started the car after totally finishing and it idled OK for about 30~40 seconds and then went into an idle searching up and down and then died. Restarts OK every time and will idle for a bit and then goes into idle fluctuation and then dies.

Would a damaged O2 sensor have these symptoms? You can literally hear it shut the induction flap and then it dies. Can I unplug it without harming anything? I know I should drive it to reprogram the DME, but it is actually falling off under throttle also like the ignition has been cut and then restarts when the weight of the car runs against the engine.

PLEASE give me your opinion when you have a minute!

Thanks,
Jim

Indycam

Have you unplugged the O2 sensor and run it ?
It does no damage to unplug it and run the motor .

68CGPlt

There are certainly more informed folks than I on this forum, however I have dealt with a similiar issue recently (hunting and stalling). Based on what you are reporting I would start with the ISV. First I would check the simple stupid stuff; enusure you reinstalled it in the correct direction, check hose connections to ensure there are no air leaks. If none of these are found I personally would remove the ISV and check its cleanliness again and ensure the valve is free to move.

Can't comment smartly on the O2 sensor. I can report that a combination of ISV cleaning and an O2 sensor replacement (ISV cleaning alone did not fully aleviate my idle hunting) has cured the hunting and follow-on stall that I encountered on my 964. Good luck.

elbeee964

I had similar problems when I cleaned/thoroughly doused my ISV w/ carb cleaner. (And I mean, doused.)
Took it off, again, I recall, drained any remaining carb fluid, left it 'dry' overnight, and it worked fine the next day.

My put is far from conclusive. Just the first thing that I was reminded of.
Good luck, mssr.

Oh, last point -- when you get that motor running, again, try disconnecting the ISV electrical plug.
You'll see how critical the ISV is to simply getting your motor to idle w/o quiting.
That damned ISV is critical.

jsacrey

I know what you mean, I unplugged the ISV to see what it did and it would not idle at all. While I had it unplugged, I held the idle steady by opening the throttle. While holding the throttle open, I could hear the flap on the MAF close by itself which is what makes me think the O2 sensor is giving off crap signals.

I'll unplug the O2 sensor in the morning and see what happens. Hopefully that's what the culprit is and replacing it will cure the problem.

I was thinking over dinner that the only electronic stuff I've changed or messed with in this service was the O2 sensor and ISV, so it has to be one or the other. I did change the rotors and distributors, but they're all tight and I don't see any arcing of any kind. I did verify that I didn't misplace a wire on the distributors and the distributor belt is NOT broken.

carby

The problem could also lie with the brain (DME) that controls all these muscles...do you have a spare one you can plug in to test, it would rule out the chance it might have suffered a stroke/short and is spoiling the party...? I keep two spare, call me cautious.
Good luck, there are wise ones out there who know much more than I.

carby
www.deus.com.au

jsacrey

No I don't have a spare....it was doing OK before the maintenance job 2 days ago, but had rough idle. I'm about to go unplug the O2 sensor and see if it's the culprit!

jsacrey

The O2 sensor isn't it. It ran even rougher and won't idle at all now. I've taken the ISV out again and everybody says to test it and see if it moves freely?? Is this the little window on one side of it? How to test without damaging it?

LouZ

Just apply a 12V source to it and it will cycle. You will see the little flap snap closed, though not fully closed. Also check for vacuum leaks around the ISV as you could have knocked one off.

BTW - if you have the new O2 sensor, plug it in to the circuit and let it dangle, then start the car and check your idle.

Indycam

Have you rechecked the spark plug wires ?
Its easy to get a few crossed over .

jsacrey

Yes I rechecked them last night. I removed them one at a time and put them on the new cap so that I didn't have more than one unplugged at a time. It's not misfiring at all, it's searching for idle up and down and struggling to run.

I didn't notice it last night, but it's beeping inside the cabin after start and the ABS light is staying on. I don't have a Hammer to see what the code is. Is there a list of beep codes anywhere that you guys know of?

LouZ

What MY do you have? Later years could display the codes thru the Check Engine light.

jsacrey

It's a 1989 Carrera 4

dfinnegan

Did you disconnect, or otherwise disturb, the electric connector on the back of the AFM? There is a TSB for describing how to tie back the wire so that it does not get interference from metal contact behind the air box. I'll look for the post...

dfinnegan

AFM Connector TSB