no warm idle .......help !

johnnycoo1 · 09-23-2009, 08:08 AM

sorry first post and unfortunaltey its the usual CIS problems !

car is a standard 1988 turbo targa (UK)

has been running fine no probs -- isn't driven much but no issues , then I start i the other day .......no probs starting .......runs fine cold but as soon as it heats up it dies on idle , car drives fine but just will not idle even for a second when fully warm.

checked AUX air reg its fine , mixture has not been touched , if i disconenct power to the WUR (CPR) it will idle ok when it starts to warm up , however after re-applying power after about 30secs it starts to die..........if i pull the plug again it will start to recover ............

dunno much about this but it seems control pressure is going to high as the engine warms up and she's going lean on idle ??

why this would suddenly change i don't know

thinking blocked return on WUR or WUR needs 'tap' outwards but why this would suddenyl need adjusting beats me ?

can't find any vaccuum leaks either

help !

johnny

T77911S · 09-23-2009, 09:45 AM

check control pressures to eliminate the WUR.

could be a big air leak. when the WUR warms and leans out it would cut off. i saw a 930 that blew the IC off just enough to let in air because it was not bolted down and i think it would not idle, cant remember for sure.

johnnycoo1 · 09-24-2009, 01:14 AM

hmm , unfortunately i don't have anything to test the control pressure.......

can't find any air leaks so i adjusted the mixture slightly ........ managed to get a good warm idle after about 1/3 turn clockwise (richer) and a bit of adjustment on the idle screw........

seems to idle ok and revs ok ........ will try to drive it tonight see how she goes and i haven't tried a completely cold start yet

still i cannot understand why suddenly (almost overnight this bcame a probelem) i should have to adjust this mixture

I can't help feeling i am still masking a problem.

longhornchris04 · longhornchris04's Garage

My gut says if its sudden onset then you've got a vacuum leak. A cracked hose giving way would drastically alter the air mixture the engine gets vs. the air measured at the airbox - and thus the engine runs lean.

Of course it is possible for the WUR and other components to "just go" but more often they degrade gradually - hence the periodic tune up.

T77911S · 09-24-2009, 07:22 AM

you have put a bandaide on a gash. something has smack crackled and popped. i bet your on boost performance will be down too. changing the idle mixture will also change the mixture across the entire RPM band. chances are you are sucking in air to lean it out at idle and will be blowing it out under boost.

johnnycoo1 · 09-24-2009, 07:58 AM

yep i agree its gotta be a leak of some type ........just to drastic an overnight change to be anything else .......... just can't find it ! you would think a leak of this size would be more obvious ....... even replaced O rings on intercooler as one was a bit broken

T77911S · 09-24-2009, 09:07 AM

keep looking, you will find it. i am not familiar enough with the turbo to give you ideas other than the one experience i had with one that blew the IC off at the pipe on the left side.
good luck

johnnycoo1 · 09-25-2009, 11:41 AM

found it ! it was on the bottom side of the large pipe coming out of the air metering unit no wonder she was off

thanks for everyones input a very active and usefull forum for the 911