Max Power

While sitting at lights an hour ago, the motor would kind of hiccup and the car kind of try to jump fwd for a split second.

I currently have a check engine light throwing an egr malfunction. On more humid and cold days, the engine does the same thing until it reaches operating temp.

Today the problem at the lights was happening at regular operating temp.

Any ideas that could help pinpoint the problem??

ylekiot1

Not sure what to tell you with the limited details you gave but the only idea I have is that on my 90, the IAC valve starts to close as it reaches normal temp when at idle. Mine idles higher when it is cold and when the valve closes, it decreases the idle in three steps about two seconds apart. It only does this three step idle decrease once while stopped. It also wont do it until you are at idle at a light. So if I drive and get right on the highway for 20 miles and completely warm it up and pull off a highway ramp it will do it as I am sitting at the red light. If I am doing stop and go city driving, it will do this as soon as it hits the temp it needs after a few minutes when I am idling at a light, much quicker than the highway example. If this happens multiple times during warm up this is probably not your issue. I havent had the time to clean the carbon build up on the IAC, to make this not so noticable (which I believe is the issue) (this is the valve near the throttle position sensor, not the air valve off of the power steering pump).

ylekiot1

You might need to clean your throttle body, that will trigger that egr code. http://www.lexls.com/tutorials/EFI/throttlebody.html

You might also check your vacuum lines and check the condition of the small circle egr vaccuum modulator filter. http://www.lexls.com/tutorials/emission/egrfilter.html

Max Power

Thanks for the replies guys. I've been keeping an eye on it and I really don't know what else to add since now the problem is gone, yet the check engine light is still there.

It's so sporadic that it makes it hard to pinpoint.

I will clean my throttle body this weekend when I do my suspension. Hopefully it's really dirty haha.