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I reascently noticed my 95' 302 has developed a random pinging after startup. It is intermitant until the motor is warm. 118k miles on the clock. Anything I can do to fix that??
Sounds like it has too much advance before the computer goes into open loop mode after it warms up. After warming up the computer takes over and retards the advance so it doesn't ping anymore.
First things first, I would check the base timing. Do that, and see if it fixes it. Get the easy stuff out of the way first.
The computer always has control over the advance - it's what advances the timing at all. It's still a good idea to check the base timing. I would also check for diagnostic codes in the computer to see if it is trying to tell you anything. Here are some instructions if you've never done it before: http://www.thorssell.net/hbook/eectest.html .
Wait a sec...is this at idle or drive. I find it hard to believe that it is an ignition problem being that the PCM dumps a boat load of fuel when in open loop. Are you sure it's a "pinging" type detonation noise or possibly a knocking noise. Sometimes you hear when the motor is cold, possibly an angry lifter.
^ I agree that the noise could be a lifter or other type of tick, but the computer doesn't just dump extra fuel in open loop. It just runs with no O2 sensor feedback, so it will err on the rich side of things to be safe, but doesn't just dump a boatload of fuel for no reason.
I have some datalogged files that show me it is richer in open loop, as per wideband and EASE scanner/datalogger. A/F ratios were high 12's in open loop, that's rich.
I have a purolator oil filter in it now. The noise is not constant it is random and happens about 12 or so times before the motor gets warm. This is at idle and if driving, but I notice it more at idle.
There's nothing wrong with Purolators. In fact, they are one of the better filters available. There isn't anything wrong with Motorcrafts either, but I don't think it'll make any difference in this case. Since it is a switch, it turns on/off at around 7 psi. So even if the gauge is reading zero, there could be a little pressure there. It's not good, but it's better than nothing.