C5 vette 4l60 car will not shift over 7K

[mcclean]

To make a long story short, I've got a built setup capable of revving well over 7K (ideally looking for 7500). I have done all the obvious raising of limits but regardless of what I do I hit a wall at 7K and the car hits some sort of rev limiter. Yes.......mph params are set correctly.

My question is this: does anyone know of a hard coded limit with the 99 C5 pcm (0411) that will not allow automatic shifts over 7000? I'm past frustrated and I'm on the verge of installing a stand alone setup at this point.

Thanks for any advice,

-B

Specs - 99 auto C5, 3.90 gear, 28" pro radial, built 4l60e, 6.0 with a lot of wasted money in it....

[Alvin]

I really doubt it but could be wrong. Is there a chance your missing a rev limitor somewhere else? Like a sneaky oil temp limitor or something? Post the file if you want a second set if eyes on it.

I do have a customer with a 01 Z06 which is also a '411. The engine turned 8500 RPM on engine dyno but for sure the ECM would not allow anything higher than 8192. Hard shut down. Doesn't feel or sound like rev limitor just BANG.

[village_idiot]

post the tune, and a log

[mcclean]

I've checked all limiters and from what I can tell I have them all raised high enough.

I've attached the tune although you will see I've moved the shift points back down (pointless otherwise). I can't get a good log because every time it bangs the limiter I lose communication and the log stops.Vette_ls3top-OCT-Rev3.hpt

[blindsquirrel]

Sounds like a shit crank position sensor.

[mcclean]

Crank sensor is fine.

[kingtal0n]

Crank sensor is fine.

Was there any modification or messing around with the crankshaft reluctor? The space between reluctor and sensor is critical, and it must be perfectly symmetrical, any slight bend or deformity may lead to signal loss.

Similarly, anything that has to do with the crankshaft sensor must be checked. If the intent is to run engine beyond factory redline, then checking isn't good enough; it also should be improved. The wiring should be shielded above and beyond what the factory supplies. It should be relocated free from other wiring, far from other wiring.
The ECU plug and wiring connection between the harness and ECU is also worth inspection, as is the crankshaft sensor plug wiring insert to the sensor.

The point being, in any performance application where sensors and signals are being pressed beyond their factory expectations, special considerations are to be taken. Inspection and improvement of the most essential wiring and signal sensors is to be made for best success.

[Alvin]

Crank sensor is fine.

Is it aftermarket?

[mcclean]

The crank sensor has a perfect square waveform at various RPM's on my snap-on scope. The car runs flawless up to 7K. No issues and makes plenty of power.

My issue is that even with all the limits raised to 8K the car still hits some "limiter" at 7K. When this occurs, my scanner stops reading momentarily.

Its not the crank sensor.

[mcclean]

Is it aftermarket?

No. Factory GM sensor.

[mcclean]

Well anyone searching for this.....here is the answer. The Gen 3 computer will not allow shifts over 7K. Manual car OS's will rev past this point but auto OS's with a TCM segment will not allow shift points over the 7K limit. I can't find anyone using a 0411 style pcm with or without a TAC that is shifting this high.

Guess its time for a holley....

[A.ROY]

Well anyone searching for this.....here is the answer. The Gen 3 computer will not allow shifts over 7K. Manual car OS's will rev past this point but auto OS's with a TCM segment will not allow shift points over the 7K limit. I can't find anyone using a 0411 style pcm with or without a TAC that is shifting this high.

Guess its time for a holley....

I am VERY sure that my 411 pcm controlling my 4.8/60e combo that I swapped into my Lexus IS300 allows me to shift it above 7000rpm. I have logs (maybe had... this is a new computer since last logs) of that combo going into the 7300 range in the beginning when I was trying to dial it all in. This 411 pcm was the same for the engine, which came from a 1999 chevy silverado .

[mcclean]

I am VERY sure that my 411 pcm controlling my 4.8/60e combo that I swapped into my Lexus IS300 allows me to shift it above 7000rpm. I have logs (maybe had... this is a new computer since last logs) of that combo going into the 7300 range in the beginning when I was trying to dial it all in. This 411 pcm was the same for the engine, which came from a 1999 chevy silverado .

I would like to see logs for this. I have been able to get up to 7200-7300 on few occasions but typically it doesn't like it. Regardless I need to be around 8K so 7300 doesn't solve this. I'm 100% sure that the P01 doesn't have capabilities to carry past 7K reliably. Maybe you were working with a P59?? If so I wonder what its max capable shift RPM would be.