Engine RPM vs Engine speed

[SPi]

I have a bit of a problem car I'm working right now, it has been to several different shops, and has had the parts cannon shot at it a few times. It is a C5 Corvette with a 383, cam, heads, etc, manual trans. The runs and drives pretty good, but has what feels like an engine miss, some call it a "burble" at around 5500rpm. It only lasts 1/2 a second, and you can drive through it, and the car will continue pull to 6K and above, but it is very annoying and kills acceleration. I was datalogging a few dyno pulls today and had Engine RPM (SAE.RPM) and Engine Speed(GM.RPM24x) up on the same log. I have never really logged the two together and was curious if somebody can shed some light on how they are different. Neither PID ever matches throughout the pull, and when the "miss" happens, Engine RPM(SAE.RPM) jumps to about 1000 RPM above actual RPM for a split second and then goes back to normal, Engine speed(GM.RPM24x) doesn't move form normal. My original thought on this car was a damaged reluctor wheel, the owner swears it has been checked and rechecked and it is good, but I'm wondering if what I'm seeing is a reluctor wheel issue.
Does anybody know how these two pids are calculated and why they would be different?
The owner has changed crank sensors, cam sensors, ecm's, wire harness, plugs wires, plugs, coil packs, injectors, Map sensor etc, etc, Parts Cannon Kaboom!
I don't know much about the engine, or cam specs, other than it is a 383, and has a Callies crank.

[SPi]

Here is a log file. Check out frames 218-228.

[DrkPhx]

GM.RPM24x looks to be crankshaft reluctor related, maybe Joecar can confirm. You are getting code P0336 - Cranshaft Position Sensor A Peformance (and some other codes). Try a crankshaft sensor relearn to see if that helps. If not, your original conclusion of a damaged reluctor wheel could be correct. Does the car start okay or does it crank hard?

Some info on the DTC.

Conditions for Setting the DTC
The PCM determines that the CKP sensor signal is out of range for less than 2.0 seconds.

The following conditions may cause this DTC to set:
Poor connections Refer to Testing for Intermittent and Poor Connections in Wiring Systems.
Crankshaft reluctor wheel damage or improper installation
The sensor coming in contact with the reluctor wheel
The engine running out of fuel
If the crankshaft rotates backwards, this DTC sets. This condition is only with vehicles equipped with a manual transmission. This condition occurs when a vehicle is on an incline and the clutch is released and an engine stall occurs.

[SPi]

Sorry, forgot to mention that the car will throw a P0336 sometimes. Other than this miss at WOT throttle, the car starts and drives fine. It will only do this under load, and gets worse the hotter the engine gets.

[joecar]

Can you eyeball the reluctor wheel as you turn the crank by hand (remove spark plugs)...

does the reluctor wheel appear loose ...?
does the crankshaft have too much end play...?
does the CKP sensor look damaged or otherwise hit by the reluctor wheel...?

If you know anyone with access to high detail automotive oscilloscope, can they capture waveforms for CKP and CMP (and also of #1 injector and #1 spark trigger if 4 channel).

The PCM derives SAE.RPM directly from processing the two CKP signals (the reluctor wheel is comprised of two discs, one disc is the negative image of the other).

The PCM derives GM.RPM24x from a fixed/filtered SAE.RPM.

[SPi]

Thanks joecar, great info on the rpm signals. We have a full colour borescope as well as an oscilloscope to check the reluctor. Right now I think the customer has had so many shops spend his money without results, just parts replacers, that I want to be clear what I'm chasing here. I don't like to chase anything unless I can prove it. Out of all the things that other shops have replaced and checked, I keep going to the reluctor wheel, I just want to feel confident I'm going in the right direction and have a valid reason for my customer why I think it should be checked again. He has paid to have it checked three times already. It's hard to gain a customer's trust when they have already been taken for so much without a fix.