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Engine dies with clutch in

Ok the title might not paint the pic perfectly but here it goes. Now I haven't driven the car all that much (waiting for tag renewal), but when I did I noticed a weird symptom and am taking opinions.

Regular driving car is fine, even if I were to push and hold the clutch in to coast, and I did this to test the symptom. so here it is, if I push the car and get into boost, and then I push and hold the clutch in to coast or don't shift to the next gear quick enough, the rpms quickly drop and eventually the engines dies.

Is the idle not set properly, or?

Discuss.

Thanks, Jeremy.
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Jeremy C.
Why's he calling me meat? I'm the one driving a Porsche. (Bull Durham)
----Nothing is far away in this car!----
-1978 911 SC TURBO, Minerva Blue Targa 965 update.
-2008 550i M-Sport
Old 08-23-2011, 04:37 PM
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You win the prize for weird symptoms. My first thought is that you are way pig rich when on boost, so rich that you engine can't overcome it when getting off the throttle - especially when pushing in the clutch drops the rpms and doesn't give the engine a chance to clean up. Do you have a means of measuring AFR's when on boost?
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Mark H. 1987 930, GP White, Wevo shifter, Borla exhaust, stock everything else. The result of a massive Pelicanite good will fire recovery effort. Truely an open book, ready for the slippery slopes to modification.
Old 08-23-2011, 07:20 PM
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Max Sluiter
 
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Do you have a lightweight flywheel?
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Old 08-23-2011, 08:21 PM
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Not sure bout the flywheel, I will look at my maint records from the po.
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Jeremy C.
Why's he calling me meat? I'm the one driving a Porsche. (Bull Durham)
----Nothing is far away in this car!----
-1978 911 SC TURBO, Minerva Blue Targa 965 update.
-2008 550i M-Sport

Last edited by jcc911; 08-24-2011 at 04:03 AM..
Old 08-24-2011, 03:01 AM
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Mark, here are my AFRs when this occurred.

(taken from my other thread)

Now blips of the throttle would reach maybe 16s.
So I took the car for a ride....

AFRs were at 12.9 at idle when warm, 14.5 cruising at 3K rpm still wasn't sure if I was getting boost so I gave 'er a little.

I CAN'T WIPE THE SMILE OFF MY FACE!! This car flys!
Not to mention AFRS are 10.8 at WOT.
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Jeremy C.
Why's he calling me meat? I'm the one driving a Porsche. (Bull Durham)
----Nothing is far away in this car!----
-1978 911 SC TURBO, Minerva Blue Targa 965 update.
-2008 550i M-Sport
Old 08-24-2011, 03:04 AM
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Quote:
Originally Posted by flieger View Post
do you have a lightweight flywheel?
+1
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Old 08-24-2011, 03:41 AM
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Quote:
Originally Posted by dspturtle View Post
+1
+ 2
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Old 08-24-2011, 03:56 AM
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OK now I am curious, why would the flywheel cause this and how then would it be corrected.

I will see if I can find out later tonight. I know the clutch was replaced at one point, but do not what else was replaced also at that time.


Also, I do have a 965 IC and do not currently have the decel valve hooked up.
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Jeremy C.
Why's he calling me meat? I'm the one driving a Porsche. (Bull Durham)
----Nothing is far away in this car!----
-1978 911 SC TURBO, Minerva Blue Targa 965 update.
-2008 550i M-Sport
Old 08-24-2011, 04:02 AM
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I had the same issue with my EFI setup..decel enrichment was too fat...loaded up on excess fuel after boost. I don't have the decel valve either.
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Old 08-24-2011, 08:00 AM
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Max Sluiter
 
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Lightweight flywheel can cause the revs to drop too fast for the engine's induction system to "catch it"- at least with Motronic cars. I think CIS could suffer the same issues with the inertia of the flapper thing.
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1971 chassis, 2.7RS spec MFI engine, suspension mods, lightened

Suspension by Rebel Racing, Serviced by TLG Auto, Brakes by PMB Performance
http://www.flickr.com/photos/max_911_fahrer/
Old 08-24-2011, 10:29 AM
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So...lightweight flywheel?
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2007 911 Turbo - Not a toy
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1971 911 Targa S backroad toy
Old 08-30-2011, 07:10 PM
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Hey guys! I have a kep clutch in my old 930. I thought most of the weight was in the original clutch assembly and the flywheel isnt that heavy anyway. Next time its out im going for a light flywheel aswell. My car is cis. I think the problem mite be that a simple adjustment of the allen head mixture screw is all that be needed,it sounds like its ritch to me. I think from memory the kep is about 5kgs lighter than stock and spool up is much better.
Old 08-31-2011, 01:14 AM
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Quote:
So...lightweight flywheel?
Doesnt appear to be, the service ticket said replacement of clutch and pressure plate, resurface of flywheel.

I have increased the idle to ~1050 and only have had the opportunity to drive teh car a little, and did not notice the symptoms again.

I do think though that my timing might be off a bit, so I am trying to find out where the timing should be set.
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Jeremy C.
Why's he calling me meat? I'm the one driving a Porsche. (Bull Durham)
----Nothing is far away in this car!----
-1978 911 SC TURBO, Minerva Blue Targa 965 update.
-2008 550i M-Sport
Old 08-31-2011, 03:59 AM
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