I am sure that this subject has been discussed many times before but I am stumped on this one.
1987 944 turbo will not start cold unless starter fluid is sprayed, or air flow meter flap manually moved almost wide open
Here is what we have checked and rechecked:
residual fuel pressure holds overnight and comes right up to 38 lbs when first cranking
fuel injection temperature sensor has been replaced with new
air flow meter substituted
vacuum system checked for leaks
has spark of course

Once the car is started it starts every time right away until it is again cold the next day, the colder it is outside the harder it is to start

 

throttle position switch?

colder needs more fuel to start. which is why it won't catch without starter fluid.
i dont remember how the DME incorporates AFM signal with TPS position for idle, but could be that "wide open AFM" tells the DME to go mega-rich, enough to start.

so sounds to me like something electronic is hampering the correct fuel delivery...

 

If I read it correctly you replaced the AFM, which has internal temp sensor. Have you tested/replaced the water temp sensor in the block?

 

thanks for the replies. The first thing we did was to replace the fuel injection temperature sensor in the block, yes.
I do not know how the tps would be involved in cold start
We replaced the air flow meter with a known good one, and it made no difference.
I certainly agree that the engine is not getting the fuel it needs to start cold. And with everything we tested and replaced, there has to be something very minor that is causing the problem, and that is why we are "scratching our heads" here. Again, as soon as the car heats up it starts every time with the first one or two cranks, and does so for the rest of the day until it is parked long enough to get cold, so it is definitely a temperature issue. Fuel pressure holds all night at 20 and builds to 38 after a couple of cranks.
I guess we could substitute the control unit?

 

well we finally figured it out, of all things, there was a short in the water temperature sensor wire up in the harness due to previous melt and water getting in. Caused weird resistance readings to pin 13 on the control unit plug, and absolutely not enough resistance to start. Now starts after the first crank on the coldest day! Thank you for the suggestions and causing us to look harder to solve this nagging problem

 

My 84 944 auto starts ok but when hot won't restart. Once cooled will restart. At the ignition when car is hot doesn't turn over the stater. Sometimes I've tapped the starter with someone turning over the ignition and it fires up but if I'm on my own it's not possible. The Starter is close to the exhaust and I'm thinking it's causing the Starter to overheat. Should it have a heat shield to prevent it heating up.