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-   -   Yet another cold start stalling issue, but a bit different..... (http://forums.pelicanparts.com/porsche-911-technical-forum/696648-yet-another-cold-start-stalling-issue-but-bit-different.html)

Amochosto 08-19-2012 07:17 AM

Yet another cold start stalling issue, but a bit different.....
 
Hello,

I have searched for an answer, but the problems others have posted with cold stalling appear slightly different to mine.

My car never has a problem starting and idles somewhere around 5-600 rpm. When I am driving and the outside temperatures are cool, say below 22*c or 72*F the engine will quietly die when I have de-clutched and am coming to a stop. When the outside temperature is higher, say 26*C or 78*F the engine does not stall in these conditions, neither does this ever happen when the engine is warmed up, or when the clutch is engaged, or the gas pedal is slightly depressed.

I am totally non do it yourself with cars and have never worked on one before, but based on what I have read on this forum and the owner's manual, I suspect the following. My idle is too low, should be about 800 rpm, when I de-clutch and the fuel is cut off to the engine there is not enough time for the fuel to start flowing to get it to idle, before the engine is going too slow to save. When the engine is warmer the less viscous oil offers less resistance and the engine revs reduce less slowly and there is time to get the engine to idle.

Does anyone have any opinions or experience with this type of problem?

Thanks

Joe Bob 08-19-2012 09:11 AM

Best help is to tell us what engine and fuel system.....

Bob Kontak 08-19-2012 09:53 AM

Quote:

Originally Posted by Joe Bob (Post 6921879)
Best help is to tell us what engine and fuel system.....

Please let us know as there will be different ideas for different cars/engines.

Regarding oil viscosity, the mix of fuel and air changes as the car gets warmer. Rich fuel when starting and less fuel when warm. The air and fuel mixture will probably make the rpm drop change instead of thick or thin oil.

Amochosto 08-19-2012 10:07 AM

Quote:

Originally Posted by Joe Bob (Post 6921879)
Best help is to tell us what engine and fuel system.....

Duh. Sorry. 1984 3.2 Carrera ROW all original as far as I know. One of the options it came with was option number 154 "control unit for low emissions" but it is a type 930/20 engine, therefore no cats, and it is a Swiss market model.

That's pretty much all I can think of.

Thanks again.

Joe Bob 08-19-2012 10:18 AM

Well 5-600 rpms in itself is too low. You have a DME controlled Motronic fuel injection system.

In the old days, you could just turn a screw on the carb linkage and adjust the idle up.

You likely have an issue with the 'micro switch' on the throttle body. The switch tells the computer that the foot is off the gas and the system needs to click into idle mode......

My suggestion is get a Bentley manual and/or read up on the subject. Could also be something with a sensor for cold start.

The search feature here and on Google will get you some articles and posts on the subject.

Also consider adding your location. Some of us are just nutty enough to come visit and help....if near you.

Amochosto 08-19-2012 12:21 PM

Thanks Joe Bob, I did as you suggested and posted some info about me.


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