Tranny pros HELP!
Tranny pros HELP! Ok, heres the scoop, Ive got a 98 Z28. I bought it with 90,000 miles. It ran well for a while so I started moding, MAC headers, true duals, LS6 intake, 8.8 rearend, and a 3500 Yank converter are most of the big things. I wanted more so I put a 4200 TCS converter in it, it to worked well for a while. End of last year it started to refuse to shift under WOT, no banging the rev limiter and shifting, it just would not shift under WOT period! I figured the tranny was wore out so I put another tranny in it. Same thing no WOT shifts. I thought maybe it was the 4200 converter, so I swapped the 3500 back in. Nothing. I figured maybe the tranny I just put in was junk so I ordered a vacuum modulated Level 5 from FLP. I just got finished putting it in with the 4200 converter, same thing! I am quite frustrated to say the least. Ive tried 3 trannies and 2 converters to not avail. What the hell else could it be? Does anyone make a manual valve body for the 4L60E? Hell me out here!` Thanks.
TECH Apprentice
Joined: Jan 2002
Posts: 364
Likes: 0
From: Princeton, IN
Originally Posted by Lafngas98z
46 views and no thoughts? Do all 46 of you have six speeds or something? Come on people work with me here! Nothing?
is your TP sensor good? i know it sounds dumb but if you are not seeing WOT sensor readings then maybe it could cause a problem like this?
have you tried to start out in 1st and see if the car will shift if you move the shifter in the 2nd? or do you already do that with FLP
FLP just sent me out a new tranny, old one is sitting in the garage still. TM is gone. I have tried shifting manually, Ive tried leaving it in D, 3, 2? Nothing.
I have verified that the TPS is working with EFI live.
I have verified that the TPS is working with EFI live.
Last edited by Lafngas98z; Jan 12, 2004 at 12:31 PM. Reason: add more
No WOT upshift....... Listen up! Sounds like you might have a plugged up fuel filter or fuel pump problem, have someone watching your scanner to see if when you're @ WOT your O2 sensor indicates a lean condition & your injector PW is longer, if so your computer will be looking for a few more RPM's before it will send the command to upshift the transmission @ WOT. Hope this helps. Thanks for listening Dave & Matt
Last edited by Rock-On; Jan 13, 2004 at 04:45 PM. Reason: missed part of explination
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TECH Senior Member
Joined: Nov 2001
Posts: 9,246
Likes: 3
From: Troy, AL
What are your shift points and rev limiter settings? Sometimes upping the rev limit just 100 RPMs can make a huge difference. Here's a theory. Your shift points and rev limit were set pretty close to begin with. It worked fine after the converter change for a little while but it was VERY close to hitting the limiter on the shifts. As time passed, the converter loosened up a bit due to the lockup clutch wearing in (I know this sounds like it wouldn't have anything to do with the looseness of the converter but it does because the other clearances in the converter are effected by this.) Once the looseness of the converter reached a point, there was enough slippage in the converter to allow the RPMs to hit the rev limiter before the required shift MPH was met (in '98 the shift points were based primarily off of MPH I believe.)
Cure? Lower the shift points and/or raise the rev limiter.
BTW, you're having no trouble codes, correct?
Cure? Lower the shift points and/or raise the rev limiter.
BTW, you're having no trouble codes, correct?
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Teching In
Joined: Jan 2004
Posts: 5
Likes: 0
No WOT upshifts...... Remember, the computer still decides when to command upshift pionts based on sensor input, IE; TACH SENSOR ,,,,computer is looking for enough rpm's before shift command and this # of rpm's varies depending upon throttle setting. Now if you're at WOT and you have an exhaust restriction, IE partialy plugged cat or muffler...........or you are losing POWER/RPM's because of a plugged inline fuel filter or sock on fuel pump/bad fuel pump, than @ WOT MAX TPS voltage, your computer is looking for RPM,s that aint there and you don't get upshift, like ROCK-ON said check this with a SNAPPY SCANNER, hope this helps, thanks for listening.....
Glad that fixed the problem. 
Thanks guys, I figured it out. I had the mph for the shifts way to high. I knew from the git go it wasnt the tranny, I had always assumed it was an issue in the tuning. FWIW this freaking FLP tranny is awesome! sucker shifts like silk!
