Gatsby

iTrader: (7)

I was tuning my car with HPtuners and thought maybe I pushed some buttons wrong, but after I had the guys on HPtuners forum look at my tune and give me some tips and tables to try, I'm really convinced its a mechanical issue.

Here's the deal: it shifts into 2nd and 3rd no problem. 4th takes a while and the revs go up pretty high and then it finally shifts. That part is easily fixed with lowering my 3-4 shift point. The real issue is that while in 4th, it never cruises. What I mean is, my RPMs and speed seem to be directly linked, as if there is a mechanical link between the engine and trans, almost like the TCC is always applied. After checking the scanner though, it is not engaging at all. If i'm at around 35-40MPH with less than 20% throttle it'll be running 4000 rpms. If I blip the throttle or roll into it, the car responds super fast, like instant throttle response. But it'll redline rather quickly. If I let off the gas, the rpms and speed both drop fast directly proportional to each other.

Any idea what sensor or mechanical part could be causing this?

performabuilt

iTrader: (25)

That is odd , 4th gear is just the band applied with the 3-4 clucth. I am asumming in manual 3rd all is normal rpm wise. Even if the band came on to make 4th and it slipped the worse thing you would end up with is slipping to 3rd gear rpms. I am not sure what to tell you there. certainly odd sounds like your going back to 1st. You said its in lockup and lockup is working, Now with a 3600 stall unlocked it would seem possible to set at near 4000 rpm in 4th gear under load.

Gatsby

iTrader: (7)

It is not locking. It is saying "Apply En" in the scanner, but never locking. I think it's that I'm not hitting the mph to engage the TC. Maybe I should try lowering those MPH's in HPTuners to have the tc engage sooner? (it's set at like 60mph now based on the recommendation of another board member).

Finkledbody

60 mph seems way to high, I'd lock it closer to 40 mph in the OD gear. I have mine lock in 3rd gear at 26 mph and OD at 36 with my yank 4k stall. It acts similiar to the stock stall converter til you get on it.

Gatsby

iTrader: (7)

Okay, I adjusted the shift and TCC speeds to be a bit lower and it does shift better. But the problem persists with the cruising in OD.

TO shed more light on it. If i'm trying to cruise at 55-60, it'll be at 3500-4000 rpms. If i let off the gas completely the rpm's drop to idle (1000rpms ish), but speed will drop a bit. If i wanna go form 55-60, it revs right back up to 4000 rpms.

If i'm in 4th gear going slow, like 30 mph, and i want to accelerate, i have to rev it up to like 5000 to get it to move at all.

Is this just slipping of some sort? The other gears all work very well. When i hammer it, it downshifts properly and accelerates just fine. It only has an issue in 4th.

I'm trying to describe the issue as clearly as possible, if there's any other thing i can measure or describe let me know so we can try to diagnose this. I'm not too familiar with the inner workings of an auto transmission so I'm not sure what could be broken.

Jays_SSZ28

iTrader: (2)

Post your tune.

Gatsby

iTrader: (7)

Here is the tune, i tried posting the .cfg file and it said invalid file. Any idea whats up with that?

Jays_SSZ28

iTrader: (2)

I can't open the tune file, the scan file works.
The PID's below might help you get a better idea of whats slipping.

Gatsby

iTrader: (7)

Does it say "out of array bounds" or something? If so, you need the newest beta of HPTuner version 2.23.

I just had to download it myself to open a tune file.

I'll give those a shot, thanks.