figured it out. It was a miss due to carbon and plugs. I'll post up more in the Weird Pinging issues thread.

 

Damn,

Took it out and got a flashing CEL again just now. Flashed 12 times. No code on the SCT tuner.

 

3,457 posts and still no info in your sig about all the mods you have done,. I'm thinking you have a coil or cap,rotor,dist,cat,cracked head,or spark plug wire prob.Get rid of the MSD box if it's still on there. And not to make lite of this situation, but have you checked the lower intake gasket?

 

It's also entirely possible that the valves or valve seats are toast from the past plenum probs, depending on how long the gasket was bad and the cat. I also forgot to mention a fuel delivery prob in my other post.

 

The stuff I've done to the truck is in the "My Garage" section.

Let's see, here's what I've done:

1.Checked fuel pressure: checks out at 52psi and holds.
2. Replaced plenum gasket, and then intake manifold with edelbrock air gap.
3. Replaced plugs, cap, rotor, and checked wires with ohm meter. All checked out.
4. Have tried a new crank sensor, cam sensor, MAP sensor, TPS sensor, IAC valve, PCV valve, IAT sensor, O2 sensors, and coolant temp sensor. None stopped the ping. All were attempted one at a time to isolate the issue.
5. Have isolated every bit of the ignition system. Subtracted 1 piece of the MSD system at a time. Went all the way back to all stock and it still pinged.
6. Checked vacuum, the needle "osillates" slightly at idle, but it's not climbing and dropping. At the OD TC lockup (where it pings) vac is 24inches at 1700RPM's
7. I debated the cracked cylinder head with HankL, he didn't seem to think that would be an issue if it wouldn't ping on the 87 octane tune, but would on the 93 octane tune. A cracked cylinder wall should ping regardless of octane rating.
Running 180* T-stat, tried cooler and hotter plugs, nothing works.

 

The crank sensor is stock, not modified correct?

 

maybe the air/fuel ratio is too much on your sct tuner ??

 

what's your current SCT tune setting ?
what's your current octane in the gas tank ?
i think i recall that it didn't ping immediately after your intake install...
now it is.
so its like the pcm started out at default rich/lean, and has now "learned" to go too lean. why would it tune itself out too lean?

if the above is true, i'd go back to stock tune, reset pcm, and come forrward again.

sorry to hear about this being so much trouble. you've put a lot of time and energy into this and deserve a better outcome.

 

After doing all of that bowl-chit, have you had your cat pressure tested?

Also, stop touching me!

 

I actually had the cat cut off and visually inspected. it's fine.

Crank sensor is new and unmodified.

currently running 93 octane and the 93 tune. the 87 SCT tune won't ping on 93 octane so that tells me it ain't something like a cracked head.

and you touched me first.