Bouncing idle after stop

[astouffer]

Lately I've noticed my 2000 Protege 1.6L with 94K miles has started doing something odd after coming to a stop. The idle will drop very low and then speed back up again several times before finally settling down and smoothing out again. Any ideas whats causing this? The only other (maybe) unrelated symptom is after a long road trip the CEL light always comes on and throws a P0402 code. I took out the EGR valve and cleaned all the soot out and made sure it opens smoothly but that didn't help. Maybe its time to clean the intake manifold?

 

[Joe1989]

Mine does this on the 1.5, No idea what causeing it yet though....

and the 1.5 had no engine check light i can check

Where is the erg valve on 1.5/1.6 engines mate?

 

[Protege Patrick]

I had some weird idling problems also. But after reading MANY threads about how the MAF sensor is bad in the 2000 1.6l, I changed the sensor and the problem went away. So I would suggest either changing the MAF, or checking the Air intake ducting for any cracks. Best of luck.

 

[Thefriar]

P0402 = ? can you get the code description

The attempt to stall could be a few things from Air leaks (not vacuum leaks!!! this would be between maf and throttle plate) to poor compression, and even sticking valve problems and valve guide problems


take vacuum readings and interperate those to get a direction to head. Remember you loose about 1 in/hg per 1000 ft elevation though just keep it in mind

 

[astouffer]

P0402 is EGR flow excessive. But that never shows until the day after a long road trip. Last summer I replaced the flexible intake hose because the old one was dry rotted and cracked. I'll start checking for loose hoses and see what the vacuum reads.

 

[Thefriar]

If the egr is slightly stuck open at idle or doesnt shut after cruise when comming to a stop, that could cause your problem. or the IAC closing off too much or not opening up at all could cause it as well