Reluctant Hot Start

[DaveBoettcher]

My 1988 944S starts perfectly when cold - you don't even hear the starter motor turn before the engine is running at normal tickover speed.

However, when hot, starting is sluggish: the starter turns the engine a few time before it catches, and then it runs slower than normal tickover, and seems to want to stall until a blip on the throttle kicks it into normal behaviour.

This happens to a degree whenever the engine is warm, but gets worse the hotter it is, and the hotter the weather is. In cold weather it is only just noticeable: in hot sunny weather it is much worse.

I am guessing that it is a fuel/vapour problem somewhere, but where to start? Has anyone experience of this kind of problem? Thanks in anticipation guys!

[blown 944]

I just fixed a problem similiar o this and it was a loose connection in my DME on my 951.

You can tap the DME with a screwdriver lightly when it is showing these symptoms and see if you get a better condition.

I had done this a few times and then pulled it a apart and fixed it with no problems since and it's been hot!!

[bholmes]

I had a similar problem that turned out to be a combination of leaky fuel injectors and a vacuum leak. I fixed those and it's a lot more compliant.

[Blondie]

Just fixed this problem with my car.

Turned out to be the reference sensor gap. It was gapped when the weather was rather cold...now that its summer, I had to regap them as the hot engine+hot/humid weather pulled them too far away from the flywheel.

When the engine was cold, however, they were close enough to the right gap that the car would start just fine.