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surging idle on start up

M

Mr.FixitNorm

New member
Not sure if this has been covered before but for quite a long while I've had this oddity when starting, the car starts perfectly within 2 -3 secs of turning the key. If I let the car idle, the rpm surges between 600 - 1400rpm for 10secs or so then settles at about 850-900 ( engine still cold at this point )
during the summer time if I drive off after 10secs or so the cars fine, In the winter the engine revs surge for longer and if I drive off and stop at the bottom of our road ( 300rds ) the engine will sometimes surge so much as I stop it will stall.

Is this to do with the infamouse DME relay or some other sensor ? All other times the engine runs superbly.

Cheers

Norm
 
Is it a 16v or a 2.58v?

I'd look at three things, DME temp sensor, *cheap about 10quid at gsf, Idle control valve, not so cheap, and worth checking your fuel pressure regulator (FPR)as a few of us have had idle probs due ot these recently. A good way to check is to start the car and pop the vacuum pipe off the fuel press reg and see if any fuel comes out, (be careful if it does, you dont want a fire, so do it with a mate who can shu t the motor off pronto. There should be no fuel comeing out of the vaccum or it will be just sucked in the inlet.

what doo your plugs look llike, sooty black? if so, FPR isposs goosed. If they look ok, idle control valve, but worth replacing the dme temp sensor IMO too;
 
Sorry, it's an `88 944S 16valve, last time I checked the plugs they looked ok, I must admit my first thought was it's temp. related but not really sure where to start. I didn't want to start down the keep replacing parts till it's cured route - this is fine for cheap to run shed , but not advisable with a 944 ( or any Porsche for that matter !!! )

Thanks for the tips though, if this bloody rain stops tomorrow I'll try and find the DME temp sensor - is there a way to test it ??

Cheers,

Norm
 
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