Hi all,
I went racing today ('94 SS, 355", 4l60e, NVram)
Once the track warmed up, leaving the line and then using full throttle in first was good. 1-2 shift was nice (selector in 2, and then moved to 3 after 5500rpm in 2nd.)
But the 2-3 shift just wasn't happening! It would just smash the limiter (set 6450, but 1 log showed over 6600) at the top of second and probably hold that if I let it.
Aborted first run early, multiple times tried reducing the shift kph, 134 to 125 to 118 and always all values from 80% TPS upwards. No note worthy change. I think I just learnt to get off the gas and back on to force the shift and then ride it out.
By the end of the 5th run, and breaking out in my (slow) class, and oil blowing past the front valley/manifold seal, I decided to pack it in, frustrated and beaten.
I am starting to suspect 3rd gear clutch pack.
But open to tuning suggestions before pulling the box.
The 2.5hr drive home was fine and normal. I logged the start of this too.
2-3 shift not happening at the drags - WOT!
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RyanK
- Posts: 6
- Joined: Wed Jul 19, 2023 2:16 pm
- cars: Holden VY V6
Holden VY SS
Holden VY Adventra CX8
Holden VZ Adventra CX6
Jeep Grand Cherokee WJ
Re: 2-3 shift not happening at the drags - WOT!
Did the log show the PCM commanding the shift when it was supposed to?
If so, you most likely have a pressure issue.
Make sure the tune is commanding high line pressure in the logs.
I tuned a guys LS1 that someone had stuffed the tune on and it was running in a low load part of the map at WOT.
That was causing the transmission pressure to be very low.
If that's not the case I'd be putting a pressure gauge on the trans.
If everything checks out it could be your 3/4 clutch pack but from my experience when they go they go completely since the plates warp very easily.
If so, you most likely have a pressure issue.
Make sure the tune is commanding high line pressure in the logs.
I tuned a guys LS1 that someone had stuffed the tune on and it was running in a low load part of the map at WOT.
That was causing the transmission pressure to be very low.
If that's not the case I'd be putting a pressure gauge on the trans.
If everything checks out it could be your 3/4 clutch pack but from my experience when they go they go completely since the plates warp very easily.
Re: 2-3 shift not happening at the drags - WOT!
is there a parameter for the WOT shift RPM? maybe it's needing to see that before it will shift?
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immortality
- Posts: 3426
- Joined: Thu Apr 09, 2009 12:31 pm
- cars: VH, VN, VS, VX
Re: 2-3 shift not happening at the drags - WOT!
It seems it was a combination of errors, shift speeds set to high, kickdown settings not matching and VSS error contributing and possibly a transmission issue as well. We've got it shifting now but is a bit lazy on the 2-3 shift.
Here is a good question, what is the expected converter slip on a stock converter? At WOT we are seeing about 600rpm slip.
Here is a good question, what is the expected converter slip on a stock converter? At WOT we are seeing about 600rpm slip.
Re: 2-3 shift not happening at the drags - WOT!
Yeah, here's an update.
6-8months ago I tried adjusting the VSS ratio to suit the different diff ratio and tyre size. I couldn't make heads or tails of it so adjusted the PPR code (even though the note says don't touch) about 10% and achieved a GPS speed match to the ecu trans speed.
Then a few months later at the local 1/8 street drags I dialed in the 1-2 shift, lifted the limiter a fraction and held 2nd right through the finish line (basically at 6400) before backing out completely obviously.
Fast forward another busy 6months, I had forgotten all about the earlier changes and then wondered what was up with my 2-3 WOT shift. Looking back at the log on the final run, the ecu said 2-3-2-3-2-3 before holding 3rd. This was a speed vs bad tables error.
Over the weekend, immortality and I have reinstated 40ppr code, got the VSS codes correct for gps match, dropped the WOT kickdown to something below the upshift, test run WOT through the 1-2 & 2-3 shifts and it's running great.
No more oil on the top of the water pump either (that must have been a repeated limiter issue)
Good to know about the 3-4 clutch pack thank you RyanK
6-8months ago I tried adjusting the VSS ratio to suit the different diff ratio and tyre size. I couldn't make heads or tails of it so adjusted the PPR code (even though the note says don't touch) about 10% and achieved a GPS speed match to the ecu trans speed.
Then a few months later at the local 1/8 street drags I dialed in the 1-2 shift, lifted the limiter a fraction and held 2nd right through the finish line (basically at 6400) before backing out completely obviously.
Fast forward another busy 6months, I had forgotten all about the earlier changes and then wondered what was up with my 2-3 WOT shift. Looking back at the log on the final run, the ecu said 2-3-2-3-2-3 before holding 3rd. This was a speed vs bad tables error.
Over the weekend, immortality and I have reinstated 40ppr code, got the VSS codes correct for gps match, dropped the WOT kickdown to something below the upshift, test run WOT through the 1-2 & 2-3 shifts and it's running great.
No more oil on the top of the water pump either (that must have been a repeated limiter issue)
Good to know about the 3-4 clutch pack thank you RyanK