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Corolla Dying and Rough Idling please help

Hi there,
I have a 93 Corolla LE and in October I was driving in heavy rain and the car died. Since then I have replaced the spark plug wires, plug seals, distributor cap, battery, and rotor. The car would get me from A to B, but I would always have to put it in neutral at a stop to keep it from dying. This past week we’ve had a lot of rain and it’s been really cold so my car has been dying when I slow down or stop. I gave it plently of time to heat up thinking it would help, but it died three times on the way to work. Anyways, I can’t really afford a diagnostic and was hoping someone had an idea of what the problem could be. Thank you reading and this. All help is appreciated.

I would try replacing the Idle Air Control valve.

The #1 cause of idle problems on a fuel injected engine is the IAC valve.


Also clean the throttle body

Another possibility is a vacuum leak.

All great comments so far but 1 suspect part is missing…the ignition coil. If it got soaked during the heavy rain…that could be the cause of your problem.

Thank you all so much for your help! Just an update, I have noticed my car isn’t really using any gas at all and is dying more frequently and even when I’m not stopped. Does that help narrow things down?

Is your foot off the gas pedal when the engine dies?


Thanks for getting back to me. Yeah it is.

Does the engine run smoothly and have normal power when your foot is ON the gas pedal? If so, I agree with @Tester .

Then the problem might be with the Idle Air Control valve.

When you release the gas pedal, the throttle plate in the throttle body closes quickly cutting off air into the engine.

The job of the IAC valve is to allow the proper amount of air into the engine for the idle condition when the gas pedal is released.


I support all of the suggestions so far. There are a lot of possibilities, the top ones having been already mentioned. The IAC being the most common, I’ve taken the liberty to attach a link to a drawing that shows the location of the IAC. It’ll be the “refer to 84-04” part. The drawing is showing the back of what Tester’s link shows.

You could if you’d like stop by the Toyota dealer’s parts window and request a copy of the test procedure to test the IAC for operation. The parts window guy where I go has always been happy to print a small document or a drawing for me for no charge. They kind of know me now, because I generally go in with a drawing and Toyota part number now. They still end up looking it up, 'cause they have to find out the inventory location and level and print the sales paperwork, but it simplifies the lookup for them. Perhaps if you brought in the drawing they’d be as accommodating for you as they are for me. Or perhaps someone here knows a “quick check” of the IAC system.

Vacuum leaks can be searched for by spraying starter fluid cautiously around the different areas where rubber vacuum hoses exist. A vacuum leak will draw in the volatile mist and cause the engine speed to increase. It’s gotta be running to do this though.

Things like the coil take a bit more knowledge and equipment… unless you happen to be fluent in the use of an oscilloscope. :smile:

Thank you all so very much for your help! I really appreciate it.

To answer your question, the car does just fine when my foot is on the pedal. It struggles a lot though when I accelerate after idling or even when I’m just coasting and I try to accelerate

I have a 92 Corolla with the 4afe engine, is your engine the 4afe too? It will say what it is on a sticker on the underside of the hood.

First off, check for any stored diagnostic codes. On your OBD I car this is probably done by a blink method. A jumper is set in the check connector then the codes blink out on the dashboard. Address any stored codes before assuming the problem is caused by something else.

There may be a change in design from the 92 to the 93, but on the 4afe equipped 92 the idle air control is part of the throttle body, not a separately replaceable part. That part failed on my Corolla but the problem was too high of an idle speed, not too low. So if your engine is the same and configured the same as mine, I think that’s probably not your problem.

hmmm … so what’s causing your car’s problem? Well, deferred maintenance is one possibility. Double check all the engine maintenance is up to date per the owner’s manual, spark plugs, fuel filter, engine air filter, inspection and testing of vacuum hoses and vacuum operated devices, egr system, etc. Your ignition system is probably the same as mine, which means there’s an ignition module and coil inside the distributor. That could be the problem. A shop should be able to diagnose that without much difficulty.

One final idea besides the good ideas posted above, on my Corolla anyway there’s an idle air speed screw that has to be re-adjusted once in a while. That’s part of the routine maintenance procedures when doing a tune-up, along with setting the ignition base timing. . It may be just that the throttle body has clogged up a bit and you need to compensate by increasing the air bleed through that port. Or the ignition timing is off a bit.

If you’ve already checked all that stuff and still a no go, then ask a shop to do a fuel pressure test.

92 and 93 Corollas are different body styles

Does anyone not know by now that George has a 1992 Corolla?

In 93 the Corolla body style was indeed changed, but the engine was the same 1.6 L, at least for the base model. You could get a 1.8 L as an option if you wanted.