I need some help!

[garycr14]

Hi All,
I could use some help. I have a "94" with a modified LT1, Lt4 AFR heads, LT4 intake, PE Exhaust, Ram Air, 52mm Throtle Body, MAF, Hypertech programer etc... The problem is my automatic (no jokes about I should have bought the 6 speed - if I were to do it all over again...) will not shift at wide open throtle. I've tried various shift points with the program, differtent rev limiter points, even reprogramed back to stock. I had a reputible vette mechnic look at it, ran a scanner found no error codes. I have taken it to 2 different transmission experts, both say there is nothing wrong with the tranny, must be in the programming. Does anyone have any ideas (again no jokes about selling it and buying a 6 speed, too much invested in it for now)? Thanks for your input.

 

[Hrtbeat1]

shift @ WOT

It won't shift out of 1st at wot? It won't downshift at wot? What speed/rpm/gear are you seeing this? Have you checked the fluid levels?

 

[garycr14]

Help!

Hi,

It wont up shift at WOT, it will down shift if I jump on it. It will just bounce off the rev limiter in each gear on the way up. 1st to 2nd, 2nd to 3rd. I've had the rev limiter set at 5800, 6000, 6200 doesn't matter same responce.

Thanks

 

[Hrtbeat1]

It will just bounce off the rev limiter in each gear on the way up. 1st to 2nd, 2nd to 3rd. I've had the rev limiter set at 5800, 6000, 6200 doesn't matter same responce.

Thanks

Are you running in D or OD? Can you start in Low and make it shift (bump up the gear) before the rev limiter kicks in? Another question, the Rev limiter, is this the ECM rev limiter or one on a MSD, ect.? Or the one you have programed in?

What do you mean by bounce off the rev limiter in each gear on the way up? Sounds like it is shifting.

 

[garycr14]

Hi,
Doen't matter wether it is in D or OD same result. I have tried the stock programming, or factor settings, and I have tried using the Hypertech standard settings, and have tried custom settings at various rev limiter setting - all with the same result. It hits the rev limiter, does not up shift, it feels like it disingages into neutral bounces up and off the rev limiter. If while doing this I let off the accelerator it will pop into gear, but I loose at least a second for this to happen.

 

[Hrtbeat1]

reprogram shift points

You may try to reprogram your shift points. Set them somewhere well below where the rev limiter kicks in. It sounds like you may not have enough internal pressure in your tranny. Your mecchanic didn't find anything wrong with the tranny, so that may be reaching. Other than that It sounds like something with the programing or the ECM/PCM. The 4L60E is just a bit different than the 700R4, the 700R4 uses a TV cable, the 4L60E doesn't. Ahhh. There you go. Check your TPS. If you aren't getting the proper voltages that could have something to do with it. Not exactly sure but there is some sort of interface between the TPS and the tranny, maybe in the computer, that tells the tranny what the pressure should be at a given throttle position, basically an electronic TV cable. That would be my guess.

You did check the fluid level of the tranny right?

 

[garycr14]

Help!

Hi,
Yes the fluid level is fine, the first thing I check. It could be in the computer. I have a second unit which I was going to send out for custom programming. I was kind of reluctant to send it in until I at least isolate the source of the problem to make sure if it is something else, it wont effect the custom program, but it may be my only choice, unless I can figure something else out. Thanks for all of your inout to this point.

 

[garycr14]

One more thing.

One more thing I forgot to mention is that this all started to come about when I fully installed the Ram Air induction. When I had first installed the front piece, cut the hole in the bumper, and left the open air lid & K&N filter as they were, it ran fine. Once I installed the inclosed Ram Air box, I started seeing the problem. I hate to remove the box as it is a pain in the @$$ to install, I may need to try that to see if this was enough to push the limit of the computer programming over the edge. I wouldn't think so, but I will need to try anything.

 

[garycr14]

Reprogramed

Well I reprogramed the shift point to the maximum that the hypertech will do, and it actually shifts! Still bounce a little from 2nd to 3rd, but I'll just keep fine tunning until it works right. I'll post the results in the next day or two in case anyone is interested.

Thanks for youer help.