Black98T/A

iTrader: (5)

Ok I have a 98 WS6 with a newly rebuilt 4l60e. The Transmission started to not upshift at WOT before the rebuild and still does it after. With a scanner Trans mechanic said the computer isn't commanding the transmission to upshift. I had the PCM tuned and the programmer said the PCM itself is faulty. Before I buy another PCM I thought I'd see if anyone has some input thanks.

Edit:tried different stock PCM speedometer is off with both pcm's(80 is really 65) and new VSS did not correct speedo

flame

iTrader: (13)

Unless you can post the tune file nobody can really help. I would bet something in the tune is causing it though.

Black98T/A

iTrader: (5)

I had the tune originally done 2 years ago when I installed a LS6 crate engine. The trans shifted fine up until last May when I noticed it didn't up shift at WOT, the transmission started to slip right after and the cars been sitting up until 2 weeks ago. When I drove the car out of the transmission shop I noticed it was still doing it. I sent the PCM to get retuned for headers, converter and the WOT problem and that didn't fix the problem.

Old Geezer

iTrader: (3)

^^^^^^^^^^^^^^

No shift to any gear, or only specific gear[s]????

Black98T/A

iTrader: (5)

The transmission shifts fine in any and every gear except at WOT. If I'm at a dead stop and floor it it won't shift into 2nd, it just goes up to redline. If I'm at a roll and floor it it downshifts a gear and just goes up to redline. The tuner says its not his tune but the PCM.

Old Geezer

iTrader: (3)

Time to look at his "tune" file, and see if he's been messing around.
There are tables for WOT @ VSS input, and for RPM input....

Black98T/A

iTrader: (5)

He's telling me it's a "driver" in the PCM. If it's the tune how would it shift fine for a over a year when he originally programmed it..then all of a sudden fail to upshift at WOT? I then sent it back to him 2 weeks ago and now probably unrelated my speedometer is 15mph off. My speedo says 80 and I'm really doing 65. He has a 98 pcm he can sell me for $250 and reprogram it for free as I just paid him $75 for the retune. Transmission mechanic says he's 100% positive it's not inside the transmission.

2xLS1

iTrader: (25)

So your speedometer says 80 when you are going 65 yet there is no problem with the tune? Get another tuner to look at it would be my advise. Especially if your tuner is aware of the speedo error and still says it is not the tune. If the scanner says the PCM is not commanding the shift, then it is not a PCM driver issue. A driver problem would be the PCM commanding the shift and not sending the signal to the shift solonoids in the transmission.

flame

iTrader: (13)

It takes 2 things for the pcm to command a gear change. MPH and RPM. Both must be met for a WOT shift to occur. If the speedo is off start there. If the pcm can control the shift solenoids for part throttle shifts then the pcm is capable of controling them.

Black98T/A

iTrader: (5)

The speedometer was fine up until this last tune. When he programmed it originally I had 17 inch tires...now I have 295/18's in the back and that's what I put on the ordersheet. I know he screwed that up. The car still wasn't shifting at WOT when the speedo was correct.

Slowhawk

iTrader: (12)

A pcm can go bad. A sensor can go bad too and not throw any codes.

You really need to hook up with a good tuner in Florida and have them log the car and adjust the tune. Thats the easiest.

gregrob

iTrader: (8)

99% its a shitty "local" rebuild that causes this issue and NOT the tune..

Here's a little experiment, put STOCK trans tables in thing and see if it shifts. Barring any sensor.or PCM malfunction if it shifts then it could be the tune. If it refuses to shift it's likely mechanical.

Black98T/A

iTrader: (5)

If it's the tune..why would it shift fine for over a year then all of a sudden not shift at WOT? I originally thought it might be something with the Transgo shift kit which was reused with the rebuild but the Trans builder said the computer isn't commanding the car to shift at WOT. When I went for a road test with him with the scanner hooked up I nailed it about 50 mph in 4th gear and I didn't see the gear indictor on the scanner change.

gregrob

iTrader: (8)

That's why I said its usually / likely mechanical.

Black98T/A

iTrader: (5)

I guess I can get a second opinion at another trans shop. At 3/4 throttle the trans downshifts and upshifts and shift perfect in every gear except at WOT.

gregrob

iTrader: (8)

Save yourself some time and send it to someone qualified. The local rebuilds usually DO NOT WORK for higher HP applications.

Black98T/A

iTrader: (5)

Ok if it is the transmission, other then he doesn't want to work on it why is the builder telling me the computer isn't commanding the trans to upshift at WOT and it did it before the rebuild and it's doing it after?

The PCM itself being the culprit is the most logical explanation it can't be the tune it wouldn't detune itself after almost 2 years.

Phil'sC5vette

iTrader: (4)

You changed tire size and your speedometer is off 15 MPH.

Your transmission still thinks it has the tires on for which its tuned for thus all your shift tables off.

If you still have your old tires and rims which your tranny didnt have an issue with, install them back on, and see if your shifts and speedometer is correct.

transam19

iTrader: (1)

I agree with philsC5vette on this. It's worth a try before you go and pull out the trans.

Black98T/A

iTrader: (5)

I wish it was that easy except I just took off my 17 inch tires and put the 18's on. It wasn't shifting at WOT with the 17s on there. I was driving the car for a week with the 17 inch tires with the tune for the 18 inch tires. I thought the speedo would correct itself when I put the 18s on but it didn't.