If you do start playing around with the idle screw make sure you keep track of how far you turned it so if it doesnt fix it you can always go back. Start with a half turn out or counter clockwise

 

I don't want to play with the screw if it is not the problem.

 

I thought if it would be IACV or the screw, then it would constantly stay at low RPM while idle. But it goes down, and then jumps up to normal.

 

its dropping down from you reving because the IAC isnt doing its job and catching the RPM.. there fore the car will stumble and stall.

if the idle air controller is not faulty then you only have one other choice.. adjust the screw. if you dont then you;ll have to live with your car like this forever.

good luck fixing it, im sure youll figure it out its not that hard. I can imagine that is really annoying also because ive had that issue myself once and fixed it.

 

Funny part is that I don't know if IACV is not faulty. I just checked the resistance (32 ohms) and that was the only thing i was able to check. Also I don't have evoscan and cable, so when I will play with the screw to find correct setup I just need to keep track of turns. Is that correct???

 

that is correct. put a mark on the top of your screw driver and keep track of the mark as you turn it. or do whatever works for you the best.

i would have to check the manual to see what the sensor is supposed to give out but i dont know off the top of my head.

counter clockwise = more air = higher idle.

 

I just played with the screw. Car does not stall anymore, but when i drive and push the clutch, rpm jumps up and down from 1000 to 1700 until i stop the car. It looks like the IACV is bad. What do you think???

 

Tom, this appears to be exactly the same thing that's happening to mine.

Do you have a wideband? What AFR does it show when the idle stumbles like that?

 

sounds like the iac is bad.. can you disconnect it adn drive the car and see if it does the same thing to confirm it?

either that or the rom you're using has the wrong iscv table settings and you have to tweak them to meet the cars requirements.

 

I just drove with IACV unplugged and the rpm went even crazier than before. It was jumping up and down from the start (1800-3000). Even at neutral (it was not happening before).

 

Thats why I have been watching this. Same problem just not as bad.

 

Have you checked that the vacuum hose to the EGR valve hasn't blown off?

 

Both hoses on the EGR valve are OK. Same as the ones on EGR solenoid.

 

My car used to do this bad when I had an intake on it. I went back to the stock airbox and its been a lot better ever since. It will still do it if the engine is heavily loaded and I take the load off (ie pushing in the clutch), but its not nearly as bad as it was. I've just learned to live with it.. Good Luck.

 

Same thing is happening to my car. I recently had cams(s1), injectors(fic 850) and a tune. The tuner said they worked as hard as possible on the idle and said it could possibly be an exhaust leak before 02 housing or iac. It seems the colder it is the worse it gets, when its warm out it is pretty much perfect. Also light throttle especially in low rpm it goes lean on tip in then goes rich and goes.