Alrighty. I've got a nasty ping that I've been fighting to hunt down for a good while now. I would just not worry about it because I've got another 3.9L motor that I plan on building for this truck, but that's for a later discussion, and I'd like to have this one last a bit longer.

Here's a general list of things I've done with the truck in relation to the motor:

• Took off what was left of the EVAP system
• Aftermarket headers
• Open style air cleaner that was put on the truck by one of the 6 or 7 previous owners
• Champion factory spark plugs

In relation to the pinging issue:
- The dizzy took a crap somewhere around last year. The little metal crown/reluctor inside was just laying in the housing not connected to anything. I assume that there was supposed to be a little plastic piece to hold that attached to the dizzy. Where did it go? How did it stay running just fine for the 2 years before hand? No clue. you tell me.
- Put a Carquest rebuilt distributo into it just to get it back on the road again. This is when the pinging started. (I've got the initial advance dead on 8°, which is what I've read to be where it was set from factory)
- Fiddled around with with a 1 step colder heat range spark plug just to play around and see what it did. Spoiler alert: It didn't do much, if anything at all.
- Tossed in a spare computer I had from a previous repair that:
1. Didn't fix the pinging issue very much
2. isn't very happy when the motor's cold, even after letting it "settle in".
- As of not too long ago, I put in a NEW dizzy from Cardone. Was the only new dizzy available on Rock Auto. Even after installing it and getting the timing dead on 8-10°,it still pings like a mad man.

I found that the pinging "gets better" when I unplug the 2-wire temp sensor on the right of the intake. I can only assume that it's the temp sensor that the computer uses to change the advance and what not. Don't get me wrong, it still pings a good bit when I give it gas, even with unplugging that sensor. The motor pings especially bad when it it's in 3rd on the highway, doing anywhere between 55 and 87. Unfortunately I can't leave it unplugged cause the computer gets even more upset when motor is cold and tries to shut off on me.

Something else I've done recently is:
1. run Seafoam though the gas tank, didn't seem to help much.
2. Got a can of spray Seafoam, got the motor real hot, let it take just about the whole can, killed the motor with what was left of the can. Left it sitting overnight, and started it back up in the morning.

Smoked like a freight train when I started it up, as I expected. If there was any carbon buildup, I doubt there's hardly any left now. Unfortunately though, the pinging is still alive and thriving.

Of course, I could just either keep running mid or premium in it. And I would be fine with that... If prices these days weren't so got awful. The other obvious fix is to "JuSt PuT a 318 V8 iN iT". If things don't go as planned with this new 3.9L I'm building, then yes. Maybe I will. But that's not the main plan for this truck, I've got an odd obsession with the forgotten son of the 318.

Anyways, I know I'm forgetting to mention something about the truck in relation to this, but I'll mention it later if I remember. I'd like to hear some outside opinions on what on EARTH could be causing this ping. Thing's driving me up a wall and I'm heading straight for the moon at this point.

 

Have you tried setting initial timing to 6, or even 4 degrees?

 

I believe I had tried that before and it didn't seem to do much of anything, but let me give it another shot

 

Keep backing it off a few more degrees until it stops pinging...... see how far you have to go.

 

backing it off did seem to help, up until I got to 0 on the dot. It would still ping under load, but if I went back any farther the motor would get very upset and run terrible.

 

How are you setting timing?

 

Is it with a timing lite or sink timing with a scanner? There was a fix a while back ago, But everyone didn't want to do it. It was a flash up date on the PCM. But it maybe too late now. Because most dealers not have the equipment anymore.

 

What year truck?

 

Its with a timing light. I've read that you've gotta unplug the temp sensor (the 2-wire one), and then read your timing on the balancer.

1988, TBI, A/T

 

Is it possible it is running hot? Vacuum leak? That temp sensor is bad?