idle issues and stalling

[tnofear666]

I own a evo 3 and im having a few issues and could do with some advice.
on cold start it runs at 2000 rpm then once its warmed up it idles fine but cuts out at junctions. Not every time but at least 3 times a day..
also it keeps revvin itself from 1000 to 1500 and back again and so on, not always but from time to time. when it last did it i pulled a few plugs off and when i pulled the idle control valve plug there was no change. Iv removed and cleaned and tested it and its ok.. could i be right in thinking its a ecu problem? is it possible to test somehow? thanks in advance

 

[clone]

ICS playing up mate , search the forum this is a hot topic mate , all explained in there

 

[clone]

actually http://www.4gtuner.com/topic/20625-rough-uneven-idle/

 

[tnofear666]

ive tested the resistance on the ics all readings were around 28.. il take it back off and make sure its on properly.. thanks

 

[brisvr4]

Look at your fiav too. It's in the same unit as the isc and an cause idle surge.
Look on vfaq.com for more info on both.

 

[4piknup]

ive tested the resistance on the ics all readings were around 28.. il take it back off and make sure its on properly.. thanks

Plug it in while it's not installed and check it moves in and out when key is turned to run

 

[tnofear666]

ok i will do. thanks

 

[clone]

let us know how you went

 

[4piknup]

http://www.4gtuner.com/topic/19963-idle-speed-control-problems/

Post number 12 will tell you how to check ecu for damage

 

[tnofear666]

Plug it in while it's not installed and check it moves in and out when key is turned to run

it doesnt move at all. and when i disconnect the plug theres no change in the engine tone... but if i take my dump valve off it idles fine,but if i block the pipe it starts to race and when i put the dv back on the idles blipping from 1000 to 1500 rpm.. does the pipe that holds the dv need plumbing into the pipe that comes off the turbo?..

 

[khubner1]

no fear that would indicate you have a dud. it is supposed to move in and out only a fraction but it should move.

if by dump valve you mean bov yes it's mean to plumb in before the throttle and back into the intake before the turbo it then has a vac line that goes after the throttle.

the throttle changing from 1000 1500 is known as hunting either the TPS is misaligned or it's a dud try resetting it by following this how to
http://122.148.77.132/4gt-manuals/how%20to%27s/tps_adjust.html if it still does it you need a new one

 

[tnofear666]

Since i was last online ive cleaned the bov and replaced all the pipe work and the stalling has now stopped. infact once the cars warmed up it runs and idles pretty much perfect.. when on cold start though its terrible, high idle (2000-2500) then, hunting between 1000 and 2000.. if it was my tps would it show syptoms at normal running temp. aswel? . how can i check the faiv?

thanks guys :thumbsup:

 

[4piknup]

The faiv is simply a temperature controlled air valve. When cold it is open allowing a extra bit of air past the throttle so speeding the idle up. When hot it closes, stopping the extra air and slowing the idle. It has a slight transition phase as well. I imagine inside is pretty close to how a thermostat works.
Mine was stuck in the open (cold) position, I think it just had a fast idle that wouldn't slow no matter what I did.
I diagnosed this by getting engine up to temperature, then removing throttle body elbow, then blocking the faiv intake ports with a piece of masking tape (can't remember if it was left or right or both ports), pushing elbow back on and starting engine.
The result was a much slower idle. So I pulled throttle body and changed the faiv. removed masking tape of course and put it back together.
I still had a stuffed isc and burnt drivers in the ecu as well, and I can't remember what it idled like, but it's perfect now.

 

[tnofear666]

Ill give that a try then. Im going to replace the belts and tensioners any day now, so il do it all at the same time.. thanks for your help :thumbsup: