1994 camry idles rough when started cold occasionally

My son’s 1994 Camry will on occasion idle rough and stall some times when started cold. It does not always do it and there seems to be no rhyme or reason to it.

This is a 14-year-old car. ANYTHING could be wrong. There are multiple sensors that may be failing. Has all the maintenance schedule been followed? You really don’t give enough information. It could be as simple as a faulty coolant temp sensor. Has anyone (a mechanic) looked at the car?

The problem might be with the cold-start injector. This injector adds extra fuel over the other injectors when the engine is started cold. This is done to enrichen the fuel mixture on the cold engine to prevent it from running rough or stalling.

This injector is located in the upper intake runner. And because of this, the tip of the injector can become contaminated from sludge and carbon from gasses introduced into the upper intake runner from the EGR and PCV systems. So basically, the tip of the injector gets all gummed up.

So, the cold-start injector should be removed from the intake runner and inspected for contamination at the tip. If it is contaminated, clean it with carb or thorttle body cleaner. Reinstall it, and see if it fixes the problem.

And by the way, if the tip of the injector is really dirty?, it means that the throttle body/intake system could probably use a good cleaning.


I second Tester. Get the throttle body cleaned out with special attention to the idle air control passage. The IAC pintle gets crudded up and becomes sticky. Since you shut the engine off hot, the air flow cold will not be enough unless the IAC can move the pintle out some. So clean things up and you will be good for a few more years.