engine pinging when warm

zenwalk · Post by **zenwalk** » Tue Jan 22, 2008 12:13 pm

I recently disconnected the AAP pump and plugged the vac lines which greatly improved the idle when cold. It now runs extremely well when cold, but when it gets up in the normal temp. range, it pings like crazy and there's a noticeable loss of power. I've replaced the plugs, tweaked the timing but nothing seems to reduce the pinging which occurs at acceleration, deceleration and at idle but only when warmed up. I didn't think the AAP would affect the fuel mixture when warm unless the diaphragm leak was somehow helping it? The pinging seems to happen suddenly, not gradually as it warms up kind of like it occurs when the vacuum routing changes through the TVSV. I haven't tried a tank of higher octane gas but that would be a last resort. This problem definitely became apparent after disconnecting the AAP but I'm not convinced that I should just reconnect it. Would adjusting the carb float level have any effect? I have noticed that it sits below center in the sight glass (about 1/4).

Post by **Petros** » Tue Jan 22, 2008 7:26 pm

Float level will not affect ping. And it seems to me neither would disconnecting the pump. You have to see if the way you plugged the vac lines did not result in either the vac advance on the distributor went to full advance or you have a vac leak. Is it possible removing the pump caused it to run lean? (I can not see how). Either you are lean, you have a vac leak, or the distrib is too far advanced in those driving conditions (checking the timing at idle will not tell you this).

The easy way to test dist. vac advance is to disconnect the vac advance, plug the lines and drive it, if the ping goes away that is the problem. If not, double check all of the lines to make sure you did not create a vac leak.

Good luck.

takza · Post by **takza** » Wed Jan 23, 2008 5:24 am

Another member just had his car worked on for pinging and no power and they found vac leaks and the EGR on all the time.

zenwalk · Post by **zenwalk** » Mon Feb 04, 2008 10:40 am

Well, what I thought was pinging was actually valve clatter. Got worse when warm as the valve clearances increased with the heat I suppose. I didn't think the valve noise would be random/intermittent so I assumed it was ping. I adjusted the valve clearances this weekend. I set them a little less than the 0.008/0.012 specs to compensate for uneven wear. Instead of having a "slight drag" on the feeler gauge, I set them so I could just barely pull the gauge out. It sounds/runs great now with considerably more power.