What might cause a gasoline engine to "diesel" after it is turned off?

Question

1990 Jeep Wrangler 2.5L TBI - After I turn the key off the engine "diesels" - or keeps firing on some of the cylinders briefly. Within the last 10,000 miles, I got a valve job, replaced the oil pump, replaced the fuel regulator, timing chain, and verified the timing. Any ideas?

Answer 1

Carbon in the combustion chamber glowing after you shut it off may be one thing to consider.Re-check the timing too.

Answer 2

Ignition from glowing carbon deposits somewhere in the combustion chamber(s).

If it's a manual, drop it into top gear before switching off, then drop the clutch.

Answer 3

Carbon build up on plugs or the wrong heat range are common causes.