SUDDEN POWER FAILURE

I have a 1985 Porsche 944 with the 2479cc engine (non-turbo). The engine starts and runs from cold with no problems, but when it is fully up to running temperature it will suddenly stall. This has happened a couple of times, once after a long run and then again on a different occasion when I was stuck in local traffic.

I am now getting worried that the problem will get worse and next time it stalls I will not be able to start it up again and be stranded. Ted Mills The most common problem that can occur with your Porsche and the likely reason for the sudden failure is that the TDC or speed sensor is beginning to fail. On both the occasions the fault occurred when the engine was at its uppermost running temperature.

The windings of the speed sensor can be affected by heat and a tiny break in the coil will cause a failure. After a slight cooling down period the contact will re- make and normal service will be resumed.

If this is the cause of the failure you will notice that the rev counter drops immediately back to zero as if the ignition had been switched off. If this is the case it will confirm that the engine speed sensor should be replaced. There are two on your Porsche and testing may conform which one is at fault.

The 944 did also suffer from problems with the fuel pump relay, but the symptoms would be slightly different from those you are experiencing.