About a month ago my C20XE started suffering idle problems.
Symptoms are (when the engine becomes warm, idles fine cold) revs hunt firstly by dropping to 2-500rpm then buzzing back upto 1200-1500rpm, settling and then doing it again. We'd regularly lubricate the ICV with WD40 down the breather hose and it would temporarily improve the situation.
Just recently it became a lot worse, to the stage where if you came to a stop it would just stall instantly and it was difficult to pull it out of a very lumpy idle, often running on 3 cyls. However, driving on partial/full load is absolutely fine, clean torque curve once you get out of the idle zone.
So I got a new ICV and upon removing the old one I discovered a great big split in the small hose linking the ICV to the inlet manifold. So replaced that and also cleaned out the ICV with aggresive carb cleaner and re-lubricated with GT85.
It appeared last night as if it was idling well, so I left it to get hot, took it for a spin, all fine. This morning in a traffic queue it kept stalling again!!!
History of the engine:
- standard C20XE, fully rebuilt (3000 miles old) lightened flywheel and balanced crank, breather mod performed
- new temperature sensors & knock sensor
- original crank position sensor
- cone air filter and powercap, brand new AFM to Powercap hose
- tried two different AFMs, idle mixture set correctly as proven by VX exhaust gas analyser
- new throttle position sensor, set correctly
- no lamda sensors
Haven't got any ECU error codes as it's in a Nova. What I have got is a fear of driving the car in traffic, which is driving me insane!
Only thing left to change is the crank position sensor, but it wouldn't have anything to do with the little carbon canister thing that I've disconnected would it? Another thing, the engine is known to burn oil after being left to idle and get hot - this wouldn't be effecting the operation of the ICV at all would it? If so, is it worth installing a mini-K&N or something in the breather pipe?