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Lumpy running/stalling when cold
#41

Hi Andy, fancy meeting you here!

The problem with diagnosing this is that it only happens for the first few minutes you start the car each day. The engine needs to get really cold for it to happen again. There are no other symptoms. So by the time I get round yours, trying other parts wont make a difference! As I said before in the post my mechanic has offered bits off his CS which he isn't using right now so that would be my best option, but many thanks for the offer.
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#42

Maybe a silly question but could this be caused by air in the cooling system?
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#43

not likely. of course, you could bleed the system and find out.



put car slightly nose up (a driveway usually does the trick)

warm up car fully

turn heater on highest temp

turn fan on high

open bleed screw until fluid comes out

close bleed screw

open bleed screw again to make sure

close bleed screw
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94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
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#44

Cheers Flash. Where's the bleed screw?
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#45

it's a 12mm hex on top of the neck fitting at the front of the head, where the upper radiator hose goes in. if you have a very early car, you may have to remove the fuel rail cover to get to it.
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94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
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#46

Blimey I'm famous I even get dispatches in the USA
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#47

An update to this thread!

 

Car went for a service including plugs and a new fuel filter. My mechanic also lent me the MAF off his CS. The problem almost seems to have got worst! The car seems to be more intent to overfuel and stall but still runs great once its warmed up a little. How very peculiar! I did also bleed the cooling system but no change.

 

Here my current list of most likely culprits:

 - Faulty FPR

 - Faulty injectors

 - Poor conection to the MAF/ICV

 

Just re-read the thread and Tryan mentioned fuel. It occurs to me that Ive been using 98 Octane fuel (usually Shell) almost exclusively for the last 12+ months. Could that be the issue?

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#48

Possible O2 sensor? They take a bit to warm up. A cheap item to check anyway.
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#49

Post deleted, I erred :-)
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#50

Quote:Possible O2 sensor? They take a bit to warm up. A cheap item to check anyway.
 

Think I forgot to mention. I changed the O2 sensor as well!

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#51

98 should even be the fuel of choice. Maybe a cracked wire?
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#52

Update:

 

Changed the FPR to a known good one (cheers Ab54666!!).....still doing exactly the same thing!!! :whine:
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#53

Here's something interesting though.

As above I did replace the DME Temp Sensor with a non Porsche part. Then in a previous test, I checked the change in resistance on both sensors and found the original Porsche one to be slightly closer to spec. Therefore assume my current temp sensor isnt faulty......

 

I just tried unplugging the DME Temp sensor while the car was running and nothing happened. No change in idle and it didnt stall either. Is this correct?

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#54

Popped the car on a durametric today and it showed an ESTC2 (Sensor 2) temperature fault

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#55

Still going on this and refusing to give up Rock

 

Tested the DME2/Water Temp Sensor at both the sensor and the DME computer plug and its fine. I think the code mentioned above occured because I pulled the sensor with the engine running and it just logged the code.

Also tested the oil temp sensor (who knows where the actual sensor is!?!?!?!) at the DME plug and it seems to be reading ok.

 

Per Waylanders advice I tried disconnecting the carbon canister purge valve but it made no difference. But I just had a thought now and perhaps that valve is stuck open. Im going to investigate tomorrow. Any thoughts/advice/encouragement would be very much appreciated!!

 

David

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#56

Here's a quick pic of our cars when we met up last week.....

 

[Image: IMG_20150227_124127198_zpsie7rvgjf.jpg]

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#57

Come back and take another one, it's been washed now


After passing it's yearly MOT road safety check with no advisories. WOOHOO!
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#58

Spent some time on this earlier and both valves for the exhaust recirculation system are working as they should. Scratching head now. Only thing left is a dodgy DME computer or something strange happening with the fuel pump or injectors.

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#59

exhaust recirculating system???  valves???  we don't have that.

 

computer possible, but not likely

 

injectors should be cleaned regularly (every 4 or 5 years).

 

the filter should be changed every 60k miles maximum

 

there is a check valve at the filter that is known to bugger, and make it hard to start

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94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
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#60

he meant the fuel vapour recirculating valves, from the carbon canister

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