Ok so this started a couple days ago. First i noticed something was going on with the 1-2 shift. Shifting much firmer, an holdin the rpms much longer under normal driving. One time it even broke the tires loose at about 15mph. Then on the highway i noticed something else. The 3-4 shift is having problems. Itll shift into 4th an the rpms drop to 2k, but then it feels like it kicks back to third an the rpms hit 24-2500. Then it feels like it kicks back into 4th. Rpms never soar like its slippin amd it doesnt even feel like it slippin just bouncin between gears. I noticed this around 45-55mph.

I was reading on performabuilts site about some probkem with the 4l60es and havin to high pressure or something causing hard low gear shifts and problems with the 3-4 shift. But my trans was rebuilt by CPT about 5-6 years ago and im not sure if he corrected that. hope im not in need of a rebuild. Any ideas what could possibly be going on?

Car is a 95z28, 94 engine and trans, stock rear, and only boltons.

 

Ok got it on the highway yesterday and have a new symptom. Got it into 4th and went close to wot to pass someone and rpms just flew up and it slipped on the downshift and didnt catch at all

 

Ok so after doing some research all my problems seem to point to code p1870. Which is slippage in the trans which results in higher line presure. From what Ive read I need to replace the TCC valve and valve body possibly, and will not need a rebuild. I also read that I can get the tcc valve in the trans go shiftkit. Is that correct? Does my diagnosis sound correct?

 

anyone?

 

its most likely a worn/slipping 2-4 band. when the pcm stores code 1870, yes the line pressure is maxed to prevent slipping, but that does not mean its a valving issue. if its slipping like you described, you're burning away friction material and i would recommend at least a teardown, probably need a rebuild.