83 911 diesels when shut off

[307micheals]

I have a 1983 911 3.0 that diesels and is close to backfire when I shut it off. Starts and runs really well. What could be the cause?

[proporsche]

check your fuel mix..and what idle speed do you have it ?
When was the last time you have checked the distributor timing?

Ivan

[cmcfaul]

Carbon on the pistons. CR (compression ratio) is too high and or too high temps. Higher octane gas should solve the problem.

Chris

[Poopwink]

I've also experienced this intermittently in my '85 with stock 3.2. Distributor was recently serviced by respected marque-specific shop. Starts and runs like a dream, even in cold temps, but every now and again it continues to run for a very brief period after turning the key off (<1 second). I'm running 91 octane (ethanol-free). 307micheals, what fuel do you use?

[gomezoneill]

It's called post ignition not diesels.