Here is whats going on. I have a built 4L60E trans (shift kit,racing clutchs/kollen steels, upgraded sprag, beast sunshell, Billet accumulator piston, corvette servo,3-4 wide clutch band) with a 3200 FTI stall. I have put around 800miles on the trans. I went to the track recently and when the car shifts from 2nd-3rd gear under WOT it hits the rev limiter for a split second before catching 3rd gear. I tried it on the street and it does the same thing.

My buddy and I tuned it yesterday to try and fix this problem. I have heard that since the 2-3shift is so slow that maybe it was hitting the stock RPM limiter. We up the rev limiter to 6500RPM from the stock 6200RPM. We then took it for a test drive and data logged the runs. The first two passes it shifted 2-3 just fine. On the 3rd pass it did the rev limiter thing again. The data logger showed the car hitting 6200RPM and the fuel injector duty cycle dropping of to nothing. So basically it is cutting the fuel during the 2-3 shift.
I am unsure about what is going on here.

I am wondering if anyone else has experienced this and could help out. The car is a basic bolt on car with a built 10bolt w/3:73 gears. Thanks in advance!!

 

Make sure you raised the cutoff rpm vs gear, and not the p/n cutoff.

 

the rev limiter cuts fuel off when you hit the limit thats why inj dc drops off

 

Tire size and gear ratios correct in the PCM??

 

What is the difference between the cutoff rpm vs gear and the p/n cutoff? What does p/n stand for?

Yeah thats what I figured. Thanks

Tire size and gear ratio is right as far as I know.

 

P/N stands for Park/Neutral. Like stated, make sure you are adjusting the rpm vs gear.

Sometimes with a loose converter you have to lower the shift rpm to keep it from hitting the limiter. What is it set to shift at?

 

As said above Park/Neutral.

HP Tuners has a bin repository where you can look at peoples tunes and they have a brief description of what they have and what they've done.

I have seen at least two where people say they raised the rev limiter but it was only the one for p/n.

 

I'm having the same problem on a stock tranny. IT's not hitting the rev limiter, it's a completely stock car.
Transmission fluid is clean and brand new.

 

Thanks guys!! I am going to try some of the info you guys gave me. I will let you know what happens!

 

Jay, we raised the cutoff RPM yesterday and that fixed the issue! Thanks!

 

good to hear.

 

Thanks!

 

How do you raised the cut off RPM. My buddys car is doing the same thing going from 2nd to 3rd shifts. I don't want it happing to my car when Install my 3200/LT's/ORY/373s...

 

My car did the same thing when in D, but if I put it in OD it shifted fine.

 

My buddy and I fixed it by adjusting the Cutoff RPM vs.Gear tab in the Transmission tuning section. It fixed the problem right away and the car runs great now.

 

That's because when you put it in D (or 3 on Firebirds), it brings the overrun clutches on which can starve the 3-4 clutches of apply pressure which they desperately need. That's why, IMHO, it's not a good idea to drive it in D or 3 instead of OD, even in city driving, unless you need some engine breaking.