idle issues

[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

 

[Steveyb_evo3]

Revving can be coil packs or amp I had the same thing took ages to find it

Cutting out could be the same as it's no spark hence no ignition

 

[tnofear666]

Its just that when i unplug the icv theres no change in the engine tone. Is that not a sign that somethings wrong with it?.. the car runs fine under normal driving. Only cuts out at junctions.. i have a bov to atmosphere, could this even be the cause?

 

[Steveyb_evo3]

Yeah the bov could be a problem just cap both sides and try that first

 

[And@fcm]

is you lambda sensor ok?

 

[tnofear666]

is you lambda sensor ok?

i dnt know..how can i test it? i have a obd scanner but the plug doesnt fit..

 

[tnofear666]

Yeah the bov could be a problem just cap both sides and try that first

Do i need to block the vacuum hole on the plenhem? Would it be safe driving it with it blocked off?

 

[And@fcm]

i dnt know..how can i test it? i have a obd scanner but the plug doesnt fit..

you can splice into the wire to it and check the voltage, you should see it fluctuating around 0.8v

and yes if removing the dv hose then you'll have to block off the holes

 

[tnofear666]

you can splice into the wire to it and check the voltage, you should see it fluctuating around 0.8v

and yes if removing the dv hose then you'll have to block off the holes

when i remove the dump valve it idles fine. if i block the hole where the dv came off it starts to race to 2500rpm. when i put the dv back on the revs are blipping from 1000 to 1500rpm... should the pipe where i remove the dv plumb back into the pipe off the turbo?

 

[And@fcm]

sounds like air leak issues would be good to do a boost leak test

 

[miller]

yup, sounds like its the ECU trying to compensate for an air leak, especially noticeable when coming to a stop, ie revs dropping to idle.

 

[tnofear666]

i seem to have sorted the boost leak by removing all the pipes,dv, ect and cleaning and refitting.. the stalling has stopped.. its still idleing allover the place on cold start,until it warms up but then it runs and idles perfect... i see a few people saying to disconnect the fiav.. is this safe? and how is this done?..

thanks for help guys