When I push in the clutch my revs fall to 600 and then rises to 1500 falls to 1100 back up to 1500 and then falls to 750 and stays fine. I have changed the IACV and check all vacum lines, adjusted screw on the top of the TB nothing and back to stock setting. What am I missing? My vafc is set to stock setting for trouble shooting and still does this. Is it the flywheel or is it out of adjustment? and no CEL and I have reset my ecu.

99 si b16a2
Flywheel 8 lbs
Exeddy clutch
pulleys
I/H/E
vafc

 

anyone??

 

Does this only happen when you push in the clutch or when the clutch is not pressed in?

 

i'm having the same problem but the engine light came on. I'm guessing it's my oxygen sensor from the cat. I have a bad cat right now. I would check the engine code. get to your ecu and put your key in ignition, check the codes.
it happens with mine when the clutch is not pressed in and i'm at a stop.

 

Burp the coolant system by getting out all water bubbles, take off your IACV and use some brake/carb cleaner and clean that thing, and on the fast idle valve under the throttle body, you will see a plate with two screws on it. Take that off and you'll see a white spring loaded with a diaphram in the middle, screw in the white plastic piece until it's tight.

 

i was looking through helms last night and the engine code is 13? BARO SENSOR? SOMETHING LIKE THAT. could it be? I have my idle going up and down and my cat has been louder since. I don't want to ask anymore since it's rude to take over another person's post.

 

It is not only when I push in the clucth it is just when it is trying to idile after a drive when it is warm. What does tightening the screw in the thermovalve do??

 

I do not have a thermo valve....

 

There's a wax pellet in the thermo valve that expands after the car is warmed up, closing an extra air passage into the intake manifold. When the valve is adjusted too loose, the pellet can rattle around, letting air sometimes leak into the manifold, causing weird idle fluctutations.

When the idle's set too low with the idle screw the car will dip down below 750 several times and then stabilize as the computer figures out what's wrong and adjusts the IACV pulsewidth to compensate. Unfortunately the computer is pretty dumb so it never remembers to keep the same pulsewidth but re-calculates it every time... at least from my experience