Celica Forums General Discussion General 7th gen auto rpm dip problem need help.

I have a 7th gen Auto GT and when the car is in drive and you come to a full stop by holding the brake the rpm’s dip so much the engine starts shaking I’d guess close to 600rpms then it revs up a bit and goes back down over and over. If you put it in neutral it revs to 900ish rpms and stays there consistently and the engine isn’t shaking and it never shakes when driving. I’ve tried cleaning the MAF and have tried carb clean to find an air leak and no luck any other suggestions? No codes and 130k miles on the car.

Hi, have you found a solution as I deal with the same problem?

I'd personally take the throttle-body off and give it a good thorough cleaning with throttle-body cleaner.
If you take the throttle body off yourself, be careful of opening the valve with your hands. It's easy to do, that's not my point.
My point is that you can damage the valve itself by opening it fully and letting go without easing it back to closed position.
Opening it up fully isn't the problem, the snap-motion of letting go of the valve, due to the spring-action, is what can cause damage.

I'd also go the extra mile and take the idle air control (IAC) valve off the side of the throttle body while you have it off.
Both the throttle body and the IAC need new gaskets if taken off. Purchase them prior to removing anything.

Another thing to keep in mind if you remove the throttle body is that there is a coolant through-line on the bottom of the TB that will drain about half of your coolant. Keep that in mind. I'd keep coolant handy before attempting this too.

-EDIT-
I forgot to mention that I did this with my 2000 GT Auto about 4 months ago, a month into owning the car. Haven't had issues with idling or RPM stability since. Mine used to swing from 600-2000rpms wildly when put into Park. New MAF and a thorough cleaning did the trick.