Hi all, this is going to be a long one so please stick with me.
I'll start by saying that I have spoken to both my tuner and the person who rebuilt my gearbox. Both are happy to assist, but as it's such an unusual problem I thought I'd ask the guru's on here as well.
My car is a 2002 Holden Monaro LS1/4L60E(same as 2004 GTO)
I just recently rebuilt both my engine and gearbox. Prior to the rebuild, my gearbox had stopped changing into second gear at WOT and would just bash the limiter UNLESS I had it in power mode. My tuner at the time tried making it change earlier and increased the line pressure to no avail. When in power mode, it still changed as normal.
I've just had the final tune done now my engine is run in and the gearbox is still doing the same thing. With power mode off it hits the limiter, when power mode is on it doesn't.

I know most people will say it's the tune as I've read countless threads on this sort of problem. We are going to investigate this first but I'm pretty sure I agree with my tuner that this must be a gearbox problem as it started to happen prior to the rebuild. The person who built the gearbox is happy to help once we rule out the tune. As it only does it when not in power mode his first thoughts were that it must be in the tune.

I guess the big question is, assuming its not the tune, can the power button affect something inside the box to cause this problem?

Thanks in advance.

 

Ok the answer to your question is in it,
It is in the tune.
The trans is exactly the same wither you have that switch in power mode or normal nothing at all changes in the trans, What does change is Tables in the tune. It switches between two tables performance and normal. In those tables many things can be changed pressure, shift time, shift points, kickdown points and more. Probably the simplest way to test this is to simply save the normal table then copy and replace it with the performance table. Then when it works as it should go back and tailer the normal table to your liking,
I use Tunercat else I would show the two tables side by side but in your model year you are likely using HPT.
But I can with certainly say it is not a trans issue, It's a tuning issue and something different between those two tables.
Frank

 

Thanks Frank,

I did just talk to the tuner and he thinks it will be the line pressure as that's the only real difference from one mode to the other at WOT. He has suggested it would be better to increase it manually in the gearbox rather than max out what he can do in the tune. He uses HPT. I'll chat to the gearbox builder and see what he thinks. The tuner and gearbox builder have a good working relationship so I'm sure they'll have a chat between themselves and work out the best way to proceed.
Is there something that could cause lower than expected pressure even after a full rebuild? I'm only thinking this as it started to happen prior to the rebuild without any change in the tune.

 

Actually, raising the line is not always the answer , I had a guy call me with a WOT no shift 1-2 and 2-3 even with line maxed, Oddly the answer was opposite we dropped the WOT pressure in the tune 10 percent and it shifted every time. I suspect an AFL valve wear issue was the real culprit but his immediate problem at the track was solved so he was happy.
As for raising the pressure in the trans mechanically or turning the set screw in the PCS I really do not suggest this as long as with harness unplugged at about 1800 rpm you see between 210 and 230 psi with a gage.
And at least in my tune other differences do exist such as the shift time shows greater in the normal mode verses the performance mode and a pressure pullout on the 2-3 I see also.
Of course after comparing TUNERCAT old school for my 1995 impala and HP TUNERS I can see a number of things they seem to have chosen to omit.
Frank

 

Is there something that could cause lower than expected pressure even after a full rebuild? I'm only thinking this as it started to happen prior to the rebuild without any change in the tune.

Unplug harness with gage in port bring RPM to about 1800 you should see 200 to 230 psi . If you do IMO change nothing in the trans pressure wise.
But logic says if it will shift in power mode but not in normal the issues in the tune not the trans,

 

You should really have a Line-Pressure Instrument on the Transmission with a long enough hose that you can tape it to the Windshield and be able to watch the Pressure reading while the malfunction occurs.

Also, there is a lot more in the Tune than Line-Pressure that will change between the Two different Tables...
Especially the Commanded Shift Timing at a given RPM for all the Gear Changes.


When the Up-Shift to 2nd-Gear does not occur, and you let off the Throttle...
What does the Up-Shift feel like?

Is it delayed and Harsh?
Is it quick but very very soft?

How is the WOT 2-3 Shift feel?
...Can you describe it?

 

Thanks,
Responses in red.

 

Small update.
I've spoken to tuner and trans builder. The tuner is going to go over the tune(in a couple of weeks when I can get it there) and see if he can sort it. If he thinks there is something not right/out of spec, he'll speak to the trans builder who's said he'll swap out the entire valve body if necessary.
I'll update again after I have the tune checked for anyone interested.

 

You could set up a simple test to take the trans off the table. It will set codes but that is ok. Ground the lt green and yellow with black stripe wires A and B solenoids, The PCM will set limp mode but you will still have the 12v to feed them, Set up a switch or switches if you want to test more than the 1-2 so you can ground ground and unground them. Then turn both on ground and then do a run and turn off the shift sol A switch "lt green" . If it makes the shift then trans is officially and totally off the table. do this in d4 or d3 position.
To me this would be the go to absolutely determine which way to concentrate my efforts and it is simple..

 

still haven't solved this.
Line pressure was upped in the box, tune has been gone over and should change well before limiter.
I'm still convinced it's gearbox related and not tune as it started happening before the rebuild.
I went to the drags and it changes perfectly when commanded in power mode.
I'm convinced there must be something in the box that changes with the power button that's not tune related.

I'll speak to builder again and maybe direct him to this thread to see what he thinks and what we could maybe try.

 

So does this mean you flick the switch to command the shift when you want it to occur?
To set it up I just need to splice into the 2 wires, ground them both with a switch on the lt green one?

 

Granted IF there is nothing wrong with your transmission... Your power mode is just a typical "sport" button like mode in function that changes shift points and tightens up your tps. The most critical thing for wot shifts is in your upshift pressures tab in base shift pressures vs torque vs gear table in both normal and performance tabs. Its critical the values in normal are changed exactly or near exactly to what the performance table is (never place a value above 90.0 or it may cause quick shifting). Its very hard to diag this without some sort of datalog which would be very helpful to everyone here. Otherwise possibly check out your actual tps? just taking a shot in the dark. Make sure your maf is clean for good measure. This truly sounds tune related / electrical as it doesn't quite make sense since a few of my customers in AUS where we have shipped many times have described power mode as holding lower gears longer but doesn't affect WOT at all...

 

If you want to go through all the gears then you will want a switch to ground on both solenoid wires (though I have noted a few times in this condition which will basically be limp mode and you controlling shifts at max line , Sometimes they wont go down to 1st) But you can still test the shifts to all other gears. Did you try something I mentioned earler and instead of increasing, lowering the line by 10 percent? To see what happens? If the AFL is to high you could flood the solenoids and be unable to make the shift at WOT .
My go to would be the shift box with switched I have suggested if indeed the shifts are being comanded and that had been verified with data logging or with some manual manor like LED tied into the solenoid wires.
Power mode does 3 things its raises shift times . Lockup timing and line presure, Similar to tow/haul mode in trucks.
What would I do ?
1- tie two leds into the light green and yellow wire with black stripe sol A and B . Neg side of the led to the wires pos side to 12v
This will act as a make shift datalog
LEDS WILL LIGHT AS FOLLOWS
1ST - BOTH ON
2ND - A OFF -B ON
3RD - BOTH OFF
4TH - A ON - B OFF
This will act as your data log to see for sure if the comands are being given.

If it passes that test the next one would be the two switches added in pace of the LED except to ground instead. Initially have both on during start up this should set limp mode, optionally and possibly better idea with aftermarkey controller would be to cut power to controller and supply separate 12votes to pin E as I am not sure how the aftermarket controller reacts to faults if at all and if it does not go to limp could confuse your test.
Then go drive
BOTH SWITCHES ON =1ST
A OFF =2ND
A and B off = 3rd
A on and B off = 4th

Now if it passes on all of this we are back to the controller or the tune . I know it all seems like alot of hassel but you have been all over the place already so its process of elimination. Personally I still think it is a tune issue because logically to me that is all it can be with it shifting normal in power mod but not regular mode.
But even so the homemade LED data log will indeed answer that question too.

Hope this helps. I would give you a variable presure control set up also for the makeshift shift box i suggest you make with the switches but its a bit more complicated and not worth the extra effort unless the other test show nothing.
But I woudl do the 2 LEDs first if it was me as they would give us a real time manual datalog of the events in both modes.
I have helped customers with this set up for years and its been of great help solving where to go for shift timing issues and if it is indeed in the tune or a fault in the controller this will show it with absolution.
Frank

 

That statement indicates, WITHOUT A DOUBT, that the transmission is just fine. And that the problem is in the tune. NO IFS, NO BUTS, no discussion. BTW - I'm also the moderator for the Tuning section here.
And Frank, with 30+ years experience, already told you that.
If your tuner cannot figure it out, find another. Or simply copy all the "power mode" values to the normal values.
A common tuning mistake is not understanding that at WOT, BOTH (!!!) the tuned "WOT RPM" and "WOT Speed" must be satisfied for each shift. Many neophyte tuners enter too-large a value for "WOT Speed" and due to converter slippage that speed is never reached. Personally I set the "WOT Speed" values about 10% below expected values so that I can tune the WOT shifts with just the RPM table.

No one else has chimed in here, because we all know its the tune, Frank told you its the tune, yet we cannot convince you. Please respect the significant and generous time Frank has spent posting here and accept its a tuning problem.
If you decide to check your line pressure and report the readings, we will advise whether it should be increased.

 

If it shifts in power mode, then your problem is in the tune. Power mode does not change anything mechanical in the trans, it only changes the tune. Do as mrvedit says and copy the power mode values to the normal values.