Tranmission shifts harsh

[Chris611]

Hey guys, I have concern about my transmission in my truck. Its a '97 K2500 with the 4L80E and 135k miles. I added a Max-E-Torq computer about 2 years ago with a Turbo Master II. I changed transmission oil a couple months ago. When I did, I found that when the oil was changed the last time, an incorrect filter was used. It had a filter for a 4L60 I believe. It didn't have the bulges on the bottom like it should. The one I put in had the bulges. After the fluid change, when the transmission shifts, the shifts are fairly hard or harsh. I figured that the Heath Diesel program was causing this so I didn't think too much about it. But now sometimes it shifts hard and sometimes it shifts like it did before. Now I am confused on how it's supposed to shift with the new computer and what might be happening to my transmission?

Thanks
Chris

[DennisG01]

When I tried a Heath ECM, I got EXACTLY the same thing. Sometimes it would shift hard/firm, other times it would not. IIRC Bill told me that it meant something in the tranny was a little bit worn out. I don't recall what he said, though. But, regardless, I've now switched to Kennedy's ECM.

[DA BIG ONE]

The manifold pressure sensor maybe going south, it's cheap & inside pan.

Its senses tranny pressures, if pressure isn't right (low/high) the ecm sends command to adjust to correct pressure and sometimes will bang gears.

[Chris611]

Thanks guys. How would I check to see if the pressure sensor is going out? Or can you? I got an idea from Dennis' post and called Heath Diesel. The guy I talked to was helpful. He said one idea was that the shift solenoids might have gotten some dirt in them. Which would casue the shifts to go from smooth to very harsh. Suggested having them replaced or trying to change the trans oil several times and see if that helps. I will keep an eye on it. I have a PMD isolater coming hopefully Friday or Monday from Heath Diesel, so I will experiment some more after I put that in.

Chris

[DA BIG ONE]

See if there any codes!

[DennisG01]

Chris, I should add that I ONLY had the on & off again hard shifting problem with the Heath ECM. My original stock ECM, my 1st Kennedy ECM, my 2nd stock ECM (when the dealer accidentally re-programmed my 1st Kennedy ECM) and my 2nd Kennedy ECM have all been fine. I don't know if it matters, but the Kennedy ECM's were set to near-stock shift-firmness settings as I plan on eventually using Kennedy's adjustable shift-firmness controller. I also want to add that Bill Heath is a great guy to deal with and he fully stood behind his product.

[DA BIG ONE]

If you don't code 1810 it maybe nothing, if you do you need to change out the manifold pressure sensor right away.

Not to cry wolf, but the failure of the manifold pressure sensor has caused many 4L80e cases to fail, GM knew it and finally corrected problem in 99, yep, in 99 so think about how much $$$$$$$ the shops made on the backs of unsuspecting souls?

http://www.transmissionspecialty.com/

[Chris611]

Am I right that in a '97 I can't use the paperclip across the ADL port and read the number of flashes of the CEL? Does having the MaxE-Torq computer change this? Any other ways to read the codes without a code reader?

Thanks
Chris

[DmaxMaverick]

Am I right that in a '97 I can't use the paperclip across the ADL port and read the number of flashes of the CEL? Does having the MaxE-Torq computer change this? Any other ways to read the codes without a code reader?

Thanks
Chris

Correct. 1996+ is OBD II, and needs to be read with a scanner. The paper clip trick only works on OBD I, 1995 and earlier.

The chip doesn't change this, only the fuel control and other parameters.

[DennisG01]

Most auto stores like AutoZone, etc. will read your codes as a free service. They only have a generic scanner, but it will read and clear the codes. Make a note of what codes you get, then see what codes come back again (after you clear it) and let us know.

[DA BIG ONE]

Try Pep boys, discount and others they will usually read your codes for free.