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Turbo Not Boosting When Cold

944 man

944 man

Active member
I dont usually let my car boost until its warm, but this morning I was in a hurry. When the gauge showed over 1BAR + one segment the car started to falter and it couldnt reach the second segment marker.

It felt like a cycling ignition cut and it stopped as soon as I backed off, on both occasions. When the car was fully warmed up I wasnt able to duplicate this behaviour and it seemed happy enough to approach the 2BAR marker.

Any thoughts?


Simon
 
Check the coolant temp sensor values Simon, sounds like it could be very rich. Are you getting any black smoke straight after starting?
Alasdair
 
Not that Ive noticed Alasdair, but you own smoke is always difficult to see. For the cost on sensors like this, am I not as well just replacing them?

 
Another thing to consider is the state of the wiring going to the various sensors. The turbo's get very hot and the loom that runs under the manifold ( which includes most sensors) gets the hottest. For anyone still on the original loom which I guess will be most out there it's worth considering replacing this section of the loom, especially if planning mods. Next time you have the manifold off take a look and I'll bet you the loom is in a very bad state which means a possible high resistance and therefore false sensor readings.

Pete
 
Could it be as you say cycling ignition cut , when cold intake temps low so will build boost faster, when warm it will not build boost as fast.

Check for leaks?
 
Perhaps this is part of the DME programming to protect the engine. You say it is cold when you observe this symptom but its OK hot. General wisdom says to not rev your engine over 3k when cold (meaning until the oil temp is reasonably up - although most us look at water temp only) as when oil is stiff the potential is there to damage bearings, etc. Perhaps Porsche added some insurance to the DME?

P.S. - I've spun a rod bearing and ruined a crankshaft by being too aggressive with cold engines - it is NOT a myth.
 

ORIGINAL: bmnelsc



P.S. - I've spun a rod bearing and ruined a crankshaft by being too aggressive with cold engines - it is NOT a myth.
Click to expand...


NO.2 by any chance??

Pete
 
Ah... It wasn't a Porsche that I did the damage to - small block Chevy V-8 - but I imagine the knocking sound would be similar [:D]
 
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