Sage282

iTrader: (7)

It's getting closer to that time for me to dig my car out and start playing with it again when the weather warms up and I have a little issue I need to resolve that I'm hoping someone might be able to help me with. My tuner and I went out and were tuning my car and it decided that it wouldn't go into 4th at WOT any more. I had just gotten the car running (first time this trans had been in the car so I'm not super familiar with how it behaves) and it was shifting into 4th at WOT fine a few days earlier when we were tuning it. The reason we were messing with it after that was to raise the shift points. My tuner spent a long time trying to fix the issue and was unable to (I'm confident in his abilities and he has tuned many local cars that all run very well) The car is a 98' Z28 with a bolt on LS6, stock converter, and a 'built' (as in I have no idea what's been touched in it but I know it has a shift kit and was rebuilt by a shop called Jimmy's Transmission in Illinois somewhere) 4L60e. The trans seems to hold power just fine, and when it was shifting into fourth at WOT a few days before it stopped it felt VERY strong and there was no noticeable slippage. Another issue the trans has (which doesn't really bother me but may be helpful) is a very firm 1-2 shift just driving around normally (my tuner tried forever to get this resolved without having to reduce the line pressure too much and it just wasn't having it)

Could this be an issue with the valvebody? Possible tuning problem? The car shifts into 4th and drives just fine cruising around normally but won't stay in 4th above like 3/4 throttle, it just stays in third and hits the limiter. Not that I really NEED to shift into 4th at WOT, but I'd like to be able to if the occasion were to arise. Any help would be greatly appreciated

THENASCAR

iTrader: (19)

sounds like tuning, the MPH versus RPM tables probably need to be adjusted. it has to meet both criteria to shift....atleast i think so, i had a similar problem with my formula.

boostedLSX

What program is your tuner using? You might have to take it for a drive and do a wide open throttle pull while you log the data. after logging you should go back and compair the rpm value and mph value on the log and adjust your tune to match the readings. When i tune cars I usually set the MPH table 2 or 3 MPH lower so the computer hits the MPH it needs then it waits for the RPM's to hit the set point then shifts. Say you want your car to shift at 6500rpms. do a wot log. go back and compair both rpm and mph in the log. when you hit 6500rpms at that same time record the MPH. Minus 2 or 3 and enter that number in your MPH table. Hope that makes sense.

Sage282

iTrader: (7)

He uses EFILive and logs everything with a wideband while I drive around, then he'll make some changes and I'll pull over and he'll re-flash it and then go again. We spent quite a while messing with it and I seem to recall him trying that already but I can ask, thanks for the advice Aside from tuning is there any other (mechanical) reason the car wouldn't want to stay in 4th? I could see if it were slipping or wouldn't go into 4th just driving around normally but neither of those things happen

Quick Sh0t xMLx

Do you mean 3rd or 4th? Because from what I read it's not supposed to shift into 4th(OD) at WOT and why would you want to anyway. If you guys are driving around hitting 150+ so it can shift into 4th....

Edit: Nevermind I see you meant 4th, now I have to ask what possible reason do you need to run at 150+ mph for?

thunderstruck507

iTrader: (18)

This.

Not the best idea unless its clutches/valvebody/etc are specifically built for it. It can be modified to "cruise" in OD at ~3/4 throttle or more.

Sage282

iTrader: (7)

My car shifts into 4th at around 120mph so it doesn't take too long to get there, it's not like I'm out driving down the highway during rush hour doing 120 Just a few pulls here and there on rural highways. It's not necessarily that I NEED to be able to shift into 4th at WOT all of the time, but there have been occasions where I've been been inching a closely matched car on the highway and just when I'm about to pull them on the top end my car goes to shift into 4th and starts hitting the limiter. Basically it's just a matter of personal preference, do I need to be able to shift into 4th at wot? Not really. Will I do it a lot? No. Would I like to be able to should the need arise? You bet

Sage282

iTrader: (7)

Yeah, I know it's not particularly good for it, but it's not something that happens on a regular basis. I guess I'm just missing the fact that I could do it with my old trans (and even this one for about a day) when my car was cammed without any issues if I 'needed' to I'm also just curious as to what would cause it to act up all of the sudden.

Jays_SSZ28

iTrader: (2)

Ok so you're driving around with your tuner in the passenger seat. You make a run and he makes changes. Then all of a sudden it stops shifting into 4th. It sounds like he made a mistake somewhere. Did he even think to set it back to when it did work?

boostedLSX

To be honest its really hard to find out whats wrong without seeing a log file or the tune file. Usually when the trans has a problem with 4th gear theres also other problems because you have the 2-4 band and the 3-4 clutch. if it was a trans problem you would see a problem in 3rd gear or second as well. and if it were a solenoid or valve body problem the pcm would store a fail code most of the time. something like shift solenoids stuck on or off. Yes it could be possible it is the trans, but its highly unlikely a mechanical trans problem given its only 4th gear at wot. and no disrespet to your tuner. It just seems odd that it was working fine, then a few settings were changed and then it didnt work. If I could see the tune file and a log file then it would be a lot easier to diagnose.