I have 2002 ford windstar with the large v6 (vulcan) and I noticed that it has recently started pinging or knocking under acceleration. It does it when the engine is hot, not when it is cold. The problem occurs under light to moderate acceleration or just after the automatic transmission shifts. I've taken it to a diagnostic center and they have checked the EGR valve and associated systems, polled the computer for error codes (none found). I have no check engine lights or other warning lights.
Their best guesse was bad gas. I've changed brand/gas station and have run a half tank of premium through it and while the knock has diminished, it is still there. What could be causing this problem?
Wednesday, June 8th, 2011 AT 3:24 PM