Porsche Enthusiasts Club Forum

my 1983 2.5 944 has developed a reluctance to start when its hot. Sometimes it just turns over, sometimes it starts but runs so roughly the you cant pull off, sometimes it runs but is really down on power. The pattern is always the same. if it doesnt start first time, ill turn the ignition off try again. it always starts within three attempts.

one thing also to mention is cold starting, the idle is low and lumpy but fine one it warms up.

so far ive replaced the following:

DME relay
DME temp sensor
Plugs
HT leads
Coil
Fuel pump

i know from the the other hot starting threads its a bugger to diagnose, but id really appreciate any suggestions.

thanks

I have just been through this pain... check the reference sensors and if not replaced for while swap them ... and make sure the connectors are good on both terminals... I replaced all you mentioned and a lot more and so far it has run without fault since swapping these..

thanks Jenko

out of interest where did you get your reference sensors from? Porsche or aftermarket?

Glad you got yours sorted.

I am not sure as handed ovver to garage in the ned to sort out but I think aftermarket - either way they are not dear... I have also forked ot for Lyndsey Racing Reference sensor harness which cost me loads to import which I did not need as the new senosors fixed it .. so let me know if you need it ...

Mine was fixed with a new fuel pump as the check valve was goosed. It came with a new check valve.

I've finally fixed the hot start issue, it ended up being the reference sensor. i replaced the speed sensor at the same time for good measure.

The allen bolts took a considerable amount of persuading to get them out. with penetrating fluid, impact driver although i have to admit giving up on the speed sensor as i thought id rounded the head. took it to my local indy who got it out no problem. when i asked them how they did it, they said, just put a tool in and undid it mate. They did then elaborate saying they used and UJ angled socket as you cant just stick an allen driver straight into it, which is clearly where i went wrong. so for anyone else trying to get the speed sensor out, dont try just using a straight socket extension as i did.

i replaced the allen bolts with standard hex head bolts and rather then thread-locking them back in, ive used an anti shake washer. Will need to check up on this to see how well it works.

I went for Bosh replacements from ebay around £80 each, a massive saving when these are over £200 on some sites.

i still cant quite believe its fixed and keep on thinking its not going to start after a trip, but so far so good.

yay ! Mine too has been behaving since this fix ( fingers crossed)