high idle problem

[95EGCoupeVtec]

ok so heres the scoop. screwed plunger back on fitv. no suction when engine is warm. as far a iacv, i cleaned it and tried to adjust the idle with the idle screw, which doesn't do anything but when i back it out alot the car revs up and down so i screwed it back in like i was b4 i messed with it. so now if i unplug the iacv the car dies. on cold start my idle is around 2500 and after it warms up about 1200-1500. i going to check for vaccuum leaks in the next few days and make sure coolant is bled. but could the iacv be the root of the issue? my old iacv i had made the car rev up and down so i took my brother inlaws old iacv and put it on my car and now instead of revving up n down it just has a high idle. car runs perfect besides this.

 

[CAFROG]

The screw adjustment on the TB (when looking at it from passenger fender) should change the idle. When its still threaded...moving it should make the idle change. Did you make sure you were at running temp (fan turned on) before adjusting? If the idle isn't changing when adjusting the screw, I would think its something worse. The FITV....have you tried screwing it in more....or less to check to see if that adjusts your idling issue?

It sounds like this is based on another thread so I apologize for asking questions that may have been explained elsewhere. But what ECU system are you running? Can this also be a culprit???

 

[95EGCoupeVtec]

im running a chipped p28. and when i had my iacv on there it revved up and down. when i put my brother inlaws old one that he took off his car now my car idles high. i wonder if my iacv % duty cycle on my basemap is off? and yes i waited till my fan kicked on. when i put my brother inlaws new one on i did the same exact procedure as on mine and his idles perfect at 800 rpm. i'm going to check my base idle again and set it at 800 if i can and then reset ecu and plug iacv back in and if that doesn't fix it i will check for vacuum leaks. like i said, with my old one on it would rev up and down. fitv has a "minimal suction" and if i unplug my iacv the car dies. i thought that meant it was bad.

 

[95EGCoupeVtec]

also i just noticed that my bov is open during idle. idk if that would cause a vacuum leak. i have the line coming from the bov and its tapped to the fpr vacuum line. thanks. so i will need to make sure the bov is shut during idle also which i will take care of. but would that cause a vacuum leak?

 

[CAFROG]

What about your MAP sensor. Don't you often need a 4 bar MAP for boost?? (guess it depends on amount of boost)

Vacuum leak might be there. Your brother in-law's IACV shoudl work.....was it clean? Try cleaning your old one and installing it once again?

 

[95EGCoupeVtec]

good news. i took his working idle valve off of his engine and put it on mine. Success!! that fixed it. so my suspicions were correct. no vacuum leak, none of that bs. just a faulty idle valve, which i had his old idle valve on my car anyway just as a temp. but now i know it was the prob. i adjusted my idle and it idles at 800-900 rpm. what is the target rpm with the iacv unplugged? is it 750rpm?

 

[CAFROG]

Not sure unplugged but 800-900 is reaching the higher limits of idle IMO

So I am confused....you said you used your brother in law's IACV and it made idle go high but then tried it again and it worked? Whateva.....success is good.

 

[95EGCoupeVtec]

ok lemme try to explain again. my bro's iacv was bad. so he got another and i took his bad one off his car and put it on mine bc mine was in worse shape and revved up and down horribly. with his old one on my car the idle was just high instead of bouncing up and down. so his new iacv he put on his car worked fine so last night i took his working iacv off his car and put it on my car and viola, it fixed mine too so that was the prob and i ordered a new one for my car and put his working iacv back on his car. and also i adjusted my idle and my car idles at ~800 with iacv plugged in and idle screw adjusted properly. usually target idle is 800 on stock ecu.

 

[CAFROG]

Nice....800 sounds good.

I thought you were scavenging your bro's IACV in the first place.....now me understand (Geico)

 

[95EGCoupeVtec]

yup i have to get downpipe off and get o2 bung welded on and put my new borgwarner/bullseye turbo on and iacv on, then make an appt to get tuned. AND friday im gong to pick up a 4dr EG with a b7/z6 minime for my wife lol. i don't think this week can get any better!!