Cold Start Issue

[Porsche944]

I've had my '87 for just over a year and in that time I've done some major repairs (new head gasket, water pump, struts, shocks, rear wheel bearings, starter, starter ring gear, converted A/C to R-134, rebuilt front control arms, yadda yadda), but I have one problem that I have yet to resolve.

The problem does not show up until the ambient temperatures drop to around 40 degrees F or so.

On a "warm" day I can jump in the car and it will fire right up, but on a cold day it is almost as if the engine is fighting the starter.

This is not your typical slow cranking. The starter turns the engine over at a "normal" speed, but 9 times out of 10 the engine will not start, and makes a gawd-awful racket when I let go of the ignition key. If I wait a couple of seconds and try again the engine will start.

What has me worried is when I bought this car the starter ring gear had 4 broken teeth (which made the idle "lumpy"), the "nose" of the starter was cracked and there appeared to be a mark where the ring gear had contacted the starter housing.

This evidence is leading me to believe that when the ambient temperature drops below a certain point this engine is prone to develope a mechanical interference between the starter and the ring gear.

Has anyone here seen or heard of this before?

[Britwrench]

Either the reference sensor gap is wrong or you have the old type of sensor bracket. The old bracket allowed electrical "noise' so that the reference sensor was not able to establish corrct engine position. When the engine cranks it sounds like the timing is way too far advanced and the cranking speed is not consistent. You need to find the engine number and type to see if the new bracket is required.

[Porsche944]

thaks for the feed back. I'll check that out.

[ronin]

also, the loss of weight of four teeth on the ring gear is not nearly enough to cause a lumpy idle

[Porsche944]

No, but the loss of four teeth in a row will give a false speed signal to the DME which will cause a lumpy idle.

HINT: The Speed sensor counts the teeth on the ring gear, and the Reference sensor tells the DME when the engine is at TDC.