What the Hell is With the Pinging?!

N0DIH, you off ALL members should know that my entire EGR system was inspected and found "clean as a whistle." All three mechanics were STUNNED at how spotless everything is.

The timing was set to 20 degrees, factory spec. If it's changed at all it wasn't because of anything anyone has done.

One thing nobody mentioned: a bad knock sensor. I don't know if the ECM is "smart" enough to detect this. I've been told that it's probably not; just to be safe, I had all the sensors checked and everything was within factory specs.

Now, given my peculiar electrical issue, it's possible that some monkey business is at hand that ordinarily would not be. If the ECM is sensitive to this issue, it may throw some things out of whack. Likewise with any system. It's difficult to know (unless you're the electrical engineer who designed this specific system) what seemingly random effects can occur because of an electrical problem. I'm going to hope that this is the case.

I'm going to post this in my other thread but I'll mention it here: my CE light came on again tonight while on the highway. Code 53: EGR/Factory Alarm/Alternator Spike

As mentioned, the EGR is as good as it can get, at least without some kind of mod. I have no factory alarm. The alternator has been checked 4 times by 3 different people and works like a charm. It's a wiring issue.

Will the fun ever START?! =P

I don't believe it would be a bad knock sensor. The system is not designed to live in knock. The sensor is to fix things when there is a temp problem with fuel or something. As we have learned before that when the knock sensor ckt will pull out 50% or so more timing needed to kill the knock than what timing created the knock. i.e. If the timing is at 22 degrees and it starts to ping, it might take 17 to make it stop.

ok. Lets dig into pinging. The ECM program is pretty agressive for timing. Nearly 50 degrees timing can be seen at idle (not in set mode) at times. I always had an issue with pinging around 35 mph, light load, typically under gentle acceleration.

Try this, (I am from Missouri), take a vacuum hose that has vacuum (or get a hand held vacuum pump, that is best, I have one, one of my favorite tools), and rev the engine up to around 2000 rpm. Then apply vacuum to the EGR valve. You should note that engine rpm decreases some. If the EGR isn't working, that won't happen.

Now, if it DOES work, get a vacuum gauge and put it on the EGR valve line. Rev it up, it should gain vacuum. If not, trace back to the little black box on the driver's side valve cover. There is 6 lines, 3 in, 3 out. And an electrical connector. This is nothing more than a vacuum switch. On or off. The bottom 2 are fed from manifold vacuum, the top is fed from the line that goes to the front of the carb, as you are looking at the fuel inlet, just to the right of it in between the fuel line and the accelerator pump. This is the ported vacuum port formerly used for vacuum adv, now used for EGR. Make sure it is hooked up right.

If it doesn't do you have a low restriction exhaust? That will mess up the EGR valve operation. I would recommend if you keep the exhaust low restriction, then get a PORTED EGR valve from a 76 Olds 350. I think that is the one that fits. Starting 1977, GM went to a negative backpressure EGR till 1979, then changed to the Positive backpressure type through 1990 (On Olds V8 gas engines). Make sure it is a PORTED not a BACKPRESSURE type.

If you do not have a low restriction exhaust, and you have a problem still, it sounds like the valve may be damaged or the backpressure port is not working. Remove and diagnose.

Let me know what you find.