Just Happened Today - Lean at idle, flutter sound on boost - Exhaust leak?
04-15-2012, 12:31 AM
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Burning Brakes
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Location: West Chester, PA / Morristown, NJ
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Just Happened Today - Lean at idle, flutter sound on boost - Exhaust leak?
Was having a good time today at a DE.
On my last session, coming back in, I see my idle (normally 14.7-15.5, bounced between the two values, and is 14.7 solid when under min partial throttle), was 16.5-17.x! The car felt like it was idling 'lumpy', and hesitating.
Took it around a bit back to the hotel. Under boost, A/F is good (goes down like it should, in the range we want, etc). Power is there, holds boost to 14-15psi like it should.
However, I hear a fluttering sound (like an exhaust leak, NO impact on performance) under boost (5th gear, 5psi+, for example). It does seem to relate to the more exhaust it's pushing the sooner the sound comes on. I believe it sounds like it is under or behind the car (again, exhaust).
So, my questions are...
1) Are Exhaust Manifold leaks detectable with the naked eye? Best way to test without removal? and would an EM leak cause a lean condition at idle?
2) What would cause this lean condition at idle? I am running the 2.5bar vice the 3bar FPR as per A-Tune, but I've been idling spot on for month(s) now.
3) Could I have a head-gasket leak without leaking or burning any coolant or oil?
4) Lastly, and this could be normal, after coming in from hot laps, if I immediately opened the dipstick, or the oil fill, I would get a little bit of smoke from here. Dipstick never popped up (I searched threads), and the thing was quite hot, but again, normal. Operating temps are in range and never past the second line. Could this be related or is this normal?
Input welcome.
*edit*
Some more diagnosing... It's definitely missing on the cylinder closest to the front. It looks like it could be the injector or the injector wire. I dropped it off at a recommended specialist with the information and we will see what they see. Hopefully just a replacement of the wiring harness end (Bosch fuel injector clip). We'll see...
*edit*
https://rennlist.com/forums/944-turb...ml#post9456568
On my last session, coming back in, I see my idle (normally 14.7-15.5, bounced between the two values, and is 14.7 solid when under min partial throttle), was 16.5-17.x! The car felt like it was idling 'lumpy', and hesitating.
Took it around a bit back to the hotel. Under boost, A/F is good (goes down like it should, in the range we want, etc). Power is there, holds boost to 14-15psi like it should.
However, I hear a fluttering sound (like an exhaust leak, NO impact on performance) under boost (5th gear, 5psi+, for example). It does seem to relate to the more exhaust it's pushing the sooner the sound comes on. I believe it sounds like it is under or behind the car (again, exhaust).
So, my questions are...
1) Are Exhaust Manifold leaks detectable with the naked eye? Best way to test without removal? and would an EM leak cause a lean condition at idle?
2) What would cause this lean condition at idle? I am running the 2.5bar vice the 3bar FPR as per A-Tune, but I've been idling spot on for month(s) now.
3) Could I have a head-gasket leak without leaking or burning any coolant or oil?
4) Lastly, and this could be normal, after coming in from hot laps, if I immediately opened the dipstick, or the oil fill, I would get a little bit of smoke from here. Dipstick never popped up (I searched threads), and the thing was quite hot, but again, normal. Operating temps are in range and never past the second line. Could this be related or is this normal?
Input welcome.
*edit*
Some more diagnosing... It's definitely missing on the cylinder closest to the front. It looks like it could be the injector or the injector wire. I dropped it off at a recommended specialist with the information and we will see what they see. Hopefully just a replacement of the wiring harness end (Bosch fuel injector clip). We'll see...
*edit*
https://rennlist.com/forums/944-turb...ml#post9456568
Last edited by Ben951S; 04-18-2012 at 05:05 PM.
