172 Ph1 Turbo High Idle

[Alex Conway]

Afternoon gents,

Finished the last track day with an issue as ever... Car was idling at 4000rpm with oil out the breather. We'd been holding above 6500rpm down the straights which would help pressurise the crankcase. The breather vents to atmosphere, not into the inlet.

Fast forward today and stupidly we don't fire up the car for a baseline. Throttle body gets removed and it looks dry and clean. We then remove the MAP sensor and its oily. Dry it off, refit it and the car idles at 1700 creeping upwards to north of 2000, a blip of the throttle puts it on 3000 and it reduces agonising slowly, really doesn't want to come down. We remove the air temp sensor and it's clean, we refit it and the MAP sensor with some ptfe tape which makes no difference.

Any ideas where else it might leak from?

Cheers, Alex

 

[NorthloopCup]

Your sure it's not the throttle body sticking? Is it on a lpt conversion as well? So standard pistons? Only asking as oil out the breather isn't a good sign on these engines.

 

[Alex Conway]

It is indeed running low boost but it's on low compression pistons. Throttle by feel and visually was against the stops so really don't think it is the throttle. It feels free with a solid snap to it.

 

[scotty2hotty81]

Ignore the fact it's turbo charged and go back to basics, idle control valve? Throttle position semsor etc? Map and iat sensors won't cause those issues.

 

[barnesautos]

Air leak ?

 

[Dan@SJM]

Spray a s**t load of brake cleaner around the inlet. See if it reacts. Is also be doing a leak down test as said by @NorthloopCup oil out the breather isn't a good sign.