Pinging: Too Rich or Too Much Timing

[96mustang460cid]

I have an engine from an 88 T-bird. The only mods are a FMIC, rotated upper intake, and Megasquirt. For reference, I have attached my current tune.

I am working on tuning the boost'd and upper RPM regions of the engine. As I start getting into the 160 - 200 kpa region, I'm getting a noise that sounds like detonation. I was using the timing table shown in Stinger's timing thread to begin with. To retard the entire curve (trying to get rid of the pinging), I told Megasquirt that the fixed timing was set at 26* when the engine was actually set at 20*. It seems that this would retard the timing 6*, but I'm not certain. Either way, this change didn't seem to affect things. Then, I went in and pulled 2* of timing off the higher kpa in the timing table. I'm still getting a pinging sound. I don't want to hurt the engine and am trying to get this engine tuned in a timely manner.

I have the AFR set at ~11.0 - 11.3. Is that too rich? As I get higher RPM's the AFR may get a bit richer because I'm only leaning it out as I reach that point in the VE table. Is the timing curve too aggressive? I have verified that my fixed timing is set @ 20*.

Any help or suggestions is greatly appreciated!

Merry Christmas!
Michael

[Stinger]

What fuel octane? 8:1 compression? Turbo or N/A head?

While it "could" be detonation, that timing table is pretty tame and should be more than safe on 91 or 93 octane at this time of the year (should be pretty cool in OK right now). The fact that you pulled a total of 8 degrees of timing and the sound persists leads me to believe the sound ISN'T detonation, though I have no way of verifying this.

One thing to note is that using any form of sound deadening ear protection will suppress exhaust/wind noise while making it easier to hear detonation type noises. You may try that as a means to isolate the sound.

The AFR is fine, 11.5:1 is typically a good "safe" street AFR and richer than that won't "cause" detonation.