Upon starting it acts normal. Around town all is fine but after extended highway use it begins to shift really hard, jerky almost. Once you turn the key off and restart all is fine again but after another long highway spin back to the jerks. :confused:

 

I would almost be willing to bet money that you are setting a P1870 but not illuminating the MIL (you don't mention that the light is on.) That code will result in max line pressure and disabled TCC lockup. Is this a new behavior since the gears? Or programming for for them?

 

Topless I do have 3.42 gears and a Hypertech that only alows for 3.15s and 2.73s. Yes I have that code . I also have the shift firmness increased. Would this be the culprit? Thanks Top.


[Modified by Vinzvette, 8:11 PM 8/16/2002]

 

ToplessTexan,

Sounds to me like you made a good call on this one. For sure there is maximum line pressure associated with this code.

I began to get it on the old LT1 Z-28 just before the 3-4 clutch pack went out at 135K miles. Since Vinzvette has done some gear modding, he no doubt has something giving the slipping code other than in my case.

Good luck, Vinzvette.
Mark

 

It sounds like the gears and Hypertech are the associates of this problem, what should I change? Maybe shift firmness, tire height or the gear preference? Thanks guys!

 

I hope I'm not the bearer of bad news...

I haven't seen many programming solutions that correctly address gear scaling for the C5, the HPP3 isn't among them. I dug into this while investigating deficiencies in LS1-Edit that have now at long last (v1.1, 8/10/02) been corrected. The short answer is that the trans output shaft speed is not scaled correctly resulting in ridiculously high TCC slip speed values. The only non-programming workaround is to leave the gear selector in '3' on surface streets and cruise at over 80 on the highway, the goal being to avoid the operating ranges where the test runs. Good programming is a much better option.

 

Vinzvette,

Since it seems to work for a while, before the TCC disengages and the maximum line pressure sets with the code...there is the long shot that the TCC solenoid is bad or has a bad connection. I doubt it, but maybe.

Also there is a 5 valve pressure switch in the tranny accessible with the pan removed as well as a pressure valve...(from memory when I diagnosed mine in the LT1.)

The 4L60E in the LS1 has a different case but the major components are about the same in both trannys I think. No doubt the valve bodies are different. Seems that automatic transmissions are in a continual state of upgrade.

I ordered a good manual and rebuilt mine, myself. I had used Mobil I Decron lll in it since the car had 15K on it, changed along with the filter every 30K. I was surprised how good things looked on the inside. The 3-4 clutches and steels were shot at 135K, the forward clutches were worn, but that is normal wear; beyond that everything was clean and in good shape.

Topless Texan knows more about the symptoms of the gear change on the shifting characteristics than I do...since I have no experience with differential mods.

Let us know how you get things worked out.
Mark

Forgot to mention that there of course is a clutch inside the torque converter that could be worn...again...doubtful that's the problem.

I'm sure there are quite a few guys out there running 3.42 gears and doing fine. You need to give a shout for some of them. I think Buckmaster may have that set up.


[Modified by MDT, 7:57 PM 8/17/2002]