Higher Rpm Trouble

I've mentioned this issue before and it feels like its been with this engine forever. Anywho it can't run over 2500rpm without cutting out and going crazy on the tach. Seems to hold up around 2000rpm then gets up to 2500 continues to climb with pedal then goes to all of the ignition was replaced in 2020 with the TBI swap except for the power lead.
All I can think is it doesn't have enough juice. It is worse with a load. Sighs are there for incomplete combustion, maybe too advanced, or the ever present possibility of a vacuum leak. This is a 90's TBI 4.3l v6 with rv cam and flat top pistons running 87 octane. This engine should sing up to 5500rpm.
Almost reminds me of the preflight run-up checking mags.

What are your thoughts?

Video:
20230721 July 21st ignition issue by Joe with a jeep, on Flickr

 

I haven't tried but I have the Swiss army to assist in disconnecting that lead.

I'll have to guess rpm afterwards...

 

Tach stays at zero with all pedal positions.


Still starts sounding like popcorn with foot on floor.

 

It does seem like ignition since the tach is jumping around. Do you have at least 12V going to the coil and distributor pick-up? What is the timing doing when this is happening? (A dial back timing light is really handy for checking this.) Maybe look under the hood the dark to check for plug wire arcing.

I don't even know how the ignition on the 4.3s works. I'm assuming there is some sort of pick-up in the distributor that sends a timing signal to the Engine ECU, and the ECU does the timing calculation and fires the coil by grounding it? Is there a separate ignition module controlled by the ECU that drives the coil? Check all that wiring for sure. Even with new parts it's possible the pick-up in the distributor, the coil, or ignition module is bad.

 

This basically is a small cap hei running the ignition with the computer doing the advance via extra pin on modual based on rpm and map.

 

I would check the ignition control module. It is either TU or the heat transfer compound under the module has dried out causing it to overheat and act up. There's not much in that distributor to cause the problem. The pickup coil is functioning or the engine would not run, ignition module and an external coil. The tach is connected to the 4th lead at the coil plug and is receiving its signal from the ignition module.

 

I had similar issue with 98 k1500 5.7. Problem was a bad wire; a worn throttle position sensor wire grounding out.

 

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TU? Is that an auto correct for PU or something else? Thank you!

 

Let's just say it is flat on its back and dying.

 

Here's a picture of the hardware:
Lots of carbon in the back of the throttle body, I'm not sure where that would be from but will look into it. The tbi is on a 1" thick solid adapter from the kit feeding the quadrajet intake. It did run a little better this morning with the tach disconnected.

 

Last night's drive home with the tach lead snipped. I'll do some testing at lunch time.

 

Another thing to look closely at is your grounding. For example, the coil is mounted on the firewall. How sound is the ground circuit between the engine, coil and ecm for that matter?