Hello everyone in the group, I’m experiencing an issue with my 2008 Volvo S40, non-turbo, 114k miles. At startup in the morning (outside temp less than 60 degrees F) the engine starts to ping as I drive, as if I’m using the wrong octane gas. The car starts/idles and drives normally, other than the pinging. As the car warms up, the pinging slightly diminishes. Upon total warmup the pinging is gone. If I start the car from cold later in the afternoon when the outside temps are 70+ degrees F., no pinging is heard at all. The car starts and drives normally. I’m retired and don’t drive that much, maybe 75 miles a week. Gas mileage has not been affected, averaging around 21mpg. city driving. I tried using different gas, both regular and high test, no change.
I did have the oil housing assembly replaced a 2 months ago due to the normal failure of that assembly, but the car was pinging before that issue. I borrowed a code scanner hoping to find something, but no codes were found. Both Coolant and Oil levels are normal.
Perhaps someone in the group has experienced this problem before. Any ideas?

Thank you

David

 

pinging is usually a sign of a lean mix or a hot burn. Given you noted some change as the engine warms up, I'd probably start by testing/replacing the ECT and thermonstat as maintenance items. Next I'd check for things that may cause a lean condition, ie intake air leaks, (boots, vacuum hoses, injector seals etc, spray around with some flammable cleaner and consider a smoke test) and exhaust leaks (which can fool the O2 sensors). Next I'd check for issues with the PCV (check the intake tubing for any signs of oiling from the PCV and do a glove test to see if there's a crank case pressure issue) and finally do some basic head gasket checks (oil, coolant levels & colors - possibly an HC test for the coolant). You can also try pulling the spark plugs to see if they are gapped correctly and burning with the expected light gray color. After that, you may need to collect some run time data to see what the O2 sensor input reads during a drive cycle. Post up if any of these provides any clues.