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Possibly the air/heating filter?

I have a 1992 Oldsmobile Ninety-eight Elite. It just recently had an oil change and fluid check, and had the engine air filter replaced. A few nights ago, the check-engine light came on. Nothing about the car seemed different at this point, except that the previous month I would get intermittent whiffs of exhaust when running the heat (either for myself or to de-fog the windshield).

Today, I was about to head home from the store and had to de-fog the windshield… and the car stalled while trying to leave the parking lot. I started it up again, but then when I went to drive forward the car stalled again. It did this a few more times. I put the car in neutral and pushed it backwards to get out of the way of other people, started it up again and turned off the heating system before shifting gears, and this time the car was fine. It did stall again briefly while waiting at a traffic light, but then thankfully started up and got me the rest of the way home.

Once home, I spoke to a friend about this who used to fix cars back in the 70s and 80s, and he says it sounds like the filter for the heating and air conditioning system, which is different from the engine air filter. Could my friend be correct? Is there a more likely explanation? (I’d take the car in to have the check-engine code identified, but Auto Zone can’t read OBD codes prior to 1996, and money is a little tight right now). Again, nothing else sounds or feels different.

A clogged HVAC filter will NOT cause your engine to stall.
It may well lead to a fogged-up windshield, and/or poor output from the heater and A/C, but it would NOT cause your engine to stall.

If your friend actually told you that a clogged cabin air filter can cause an engine to stall, then I have to question his expertise. And…I am not even sure if your car has a cabin air filter. Not many cars had them back in the early '90s. but even if it does have this feature, that filter has absolutely nothing to do with how your engine runs.

At this point, you need to have the trouble codes read, and that could be problematic, as modern code readers are useless on pre-'96-'97 models–as Auto Zone told you. There is a procedure for getting a read-out of the trouble codes by using a paper clip to bridge the gap in some contacts underneath your dashboard, and hopefully another forum member can give you some specifics on exactly how to do this.

Before we see any trouble codes, my best guess is that the engine is in need of maintenance–or what we used to call a tune-up. When was the last time that the spark plugs and plug wires were changed? Has a mechanic checked the integrity of the exhaust system?

VDCdriver: it has been a few years since the car last had a tune-up. I do not know for sure about what was changed. As for the exhaust system, the whole muffler line was replaced 2 years ago.

Your vehicle doesn’t have a cabin air filter.

Here’s how to pull codes from your pre-OBDII engine management system.


Sounds like it could be an idle air control valve.
Are your battery and alternator in good condition? Weak batteries can cause strange things.

A lot of the pre OBDII cars also used an idle position switch that is parallel with the TPS (throttle position sensor). If the idle position switch is not making, then the computer doesn’t control the idle speed and you will have all the issues you describe.

Tester: Thank you for the codes info!

db4690: To my knowledge the battery and alternator are fine?

keith: If the idle position switch is not working right, would that actually trigger the ‘check engine’ light on the dashboard?

That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P0123) not just their translation into English and post it back here.

“Get the exact code (like P0123) not just their translation into English and post it back here.”

Joseph–A 1992-vintage car utilizes an ODB1 system, which produces two-digit trouble codes by flashing a light, and unfortunately, those 2-digit trouble codes are far less helpful than the 4-digit codes that an OBD2 system will yield.

IIRC, some mfrs changed to OBD2 in 1996, and some others changed in 1997, so this car has the older, less-helpful OBD1 system.

saganth, If the car was an OBDII, it would generate a code, although most cars that are OBDII just use the TPS to determine when your foot is off the gas instead of using a separate switch. The problem with generating a code for this is that it doesn’t have any other way of knowing that your foot is off the gas, so it has nothing to compare to. The older OBD was not that sophisticated.

I’d be looking at the catalytic converter. If you’re smelling exhaust, and the engine is stalling, that points to a possible plug in the exhaust system somewhere, and the cat is the most likely suspect. I suspect the fact that you happened to be adjusting the heating controls when it stalled was a coincidence, especially since it stalled again after you set them back the way they were.