I finally found someone to tune my '05 GXP about an hour away, so we set up a day and I went over there, we changed some parameters, and went off to start tuning, and one time the write wasn't completed but he told me to start the car (He then noticed the write wasn't complete and we rewrote it and luckily it rewrote). The next step we tried to tune after a few runs was the tranny menu's, but the tranny menu's weren't opening, it said some kind of error every time he tried to open them. So he suggested he'd contact hptuners and see how to make the tranny menus open and that we should continue to tune it once it is fixed (another day). In the week after the first tune (while I wated for the guy to contact hptuners and try to fix the menus) my car had a kinds of problems with the ABS/Traction/Stability always saying it would need servicing after driving for a bit, sometimes it would do it, other times it wouldn't (It never once did this before the tuning) The hptuners guy sent him a patch for him to apply to the program and after that and he noticed a lot more parameters and menus appeared for my car. He also saw the tapshift menu (which wasn't there before) We set up another day (yesterday) So we put a tune with torque managment removed, increased rev limiter to 6100rpm, changed a bunch of downshift settings and I drove the car, it felt a hell of a lot faster with just those changed settings, but as I was advised to try different techniques to see if it would downshift when I floored it etc. it once downshifted almost near redline and I let off right away (It shouldn't have downshifted at that speed). Another time in tapshift mode I was in first gear rolling at about 4000rpm, I gunned it and pressed tapshift but it didn't work and it went to 6500rpm!! I let off right away and he checked the parameters to see how the hell it happened and a lot of things were very unusual, like it said 8000rpm as the max shift rpm in every gear and in in upshift it said 318mph for all gears (1-2, 2-3, 3-4). Every time he changed it, it would revert back to those values. So back to a stock tune and I think I took 10 years off the life of the engine (It went to 6500rpm a total of 3 times) We didn't even get into the actual tuning of the fuel maps, etc. He noticed my intake air temps were very high though (I have a K&N intake kit with the sheild) It was in the red area (I think about 125 degrees +) most of the day and there was quite a bit of knock detected. When it went to 6500rpm, it retarded the timing I think 6 degrees.

ANYBODY with an '05 GXP that had the same problems with Hptuners? Can somebody with an '05 GXP that has a good tune send me the tune file so my mechanic who does the tuning can check and see what the differences are?

My mods are K&N filter kit, removed resonator, flowmaster mufflers with stock tips welded on.

 

I can send you my tune for a reference, but it's too large to load to the forum. PM me with am e-mail address and I'll send you my 2005 GXP file.

 

I had a problem where writing a tune back to the ECM/TCM crashed part way through the TCM write. Couldn't move the car for three days until HPT sent me a patch. Seems they forgot to add the TCM recovery routine for the LS4/4T65E-HD combo.

Haven't come across the other issues you mentioned. Not to be too brutal, but if your redline got bumped to 8000, the tuner probably screwed up and doesn't want to admit he did it.

Tapshift isn't a particularly fast shift, you do run the risk of getting into the rev limiter in tapshift mode for first gear. I just fixed the shift tables in my latest tune so that it would hold first gear until redline at WOT. The 918 springs are probably good to at least 6500, but I have shift point set to 6300.

 

Thank you for those emails! I'll send them off to the tuner and see if he finds what is different between the tunes. I hope my engine isn't on its last legs after going to 6500 3 times though!

Did you ever notice that your intake air temps were extremely hot? Mine was in the red zone before we even started to do the tune (from me driving an hour to get there)

 

The TB, MAF and IAT are essentially directly above the crossover pipe, so yeah, IAT's get high when stuck in traffic or when you've just parked the car for a few minutes.

For a while I had a fair bit of insulation wrapped around the MAF. Looked like **** but did keep IAT lower and limited heat soak - the IAT responded quicker to changes in airflow. The IAT relocation kit is probably worth installing to get the sensor away from the exhaust heat.

 

A quick update is in order:

Looks like your tuner has the 2.23 "beta" version of HPT available for tuning. This has not been generally released yet.

It seems that the Tapshift tables were made available for tuning in the beta version, they're not even visible in the latest 2.22 version of HPT that I have.

The 05 GXP will just bounce off the rev limiter until something breaks if you dont tap up to the next gear (this is different from some other tunes where the computer will shift to the next gear).

After seeing some disucssion over on the HPT forums, it seems that your tap up/tap down (TUTD) tables that show first gear shift RPM of 8000 and shift speed of 318 MPH are stock - the values have just been maxed out by GM so that the transmission won't shift until you shift manually.

 

The tap shift didn't work when I pressed it a couple of times near 5900-6000rpm in first gear and the car revved to 6500rpms by the time I reacted and let off. It should not have been allowed to rev that high. I don't know how/why the hptuners program removed the rev limiter or why it made the tapshift not work.

Also, the time when I tried out the downshift, while in D. It downshifted to too low of a gear and was almost right at redline in whatever gear it chose, so I let off right away, so I don't understand how/why the Hptuners program communicated for it to do that. (the settings say it sould have known the speed was too high to downshift two gears, so should have downshifted one gear down)

I guess this car and Hptuners just don't want to cooperate, but I paid quite a lot of money for the tune and now the tune is back to being stock right now (and the overrevving might have damaged the engine) the car feels even slower now then ever before. And the ABS/Traction/Stabilitrac keeps showing in the info center as needing servicing after all of this everytime I drive the car a bit after starting it.

I read on the HPtuners site that another person with an '08 GXP couldn't get the hptuners tune written properly, and his abs/traction/stabilitrac said it needed servicing in the info center.

 

[QUOTE=TiredGXP;11957515]



The 05 GXP will just bounce off the rev limiter until something breaks if you dont tap up to the next gear (this is different from some other tunes where the computer will shift to the next gear).

QUOTE]

When i slam into the rev limiter my engine just bogs and doesn't bounce like a manual would.

 

Sounds to me like you need to find a tuner who knows something about the LS4.

I am about a week into learning how to tune with the HPTuner software on my 08 SS. There are a lot of variables! Changing too many at once is going to cause problems.

If you are really back to the stock tune you should not have any problems. I found nothing in the HPTuner about Stabilitrac - is the fuse still in? I had thought about removing it each time that stupid Stabilitrac kicks in.

 

Only after writing the tunes back and forth I have had problems with the ABS/Stabilitrac/Traction. It writes/rewrites, so anything that is faulty or not done properly can screw the car up.

I think the thing you are feeling is the torque management. (if you straighten out after a turn and go full throttle, it bucks and doesn't let the car go anywhere until a couple of seconds (one of the worst things I ever felt in a car) The stabilitrac actually works pretty good in heavy rain and snow.

 

Sounds like differential score protection to me. This is torque management taken to an extreme. When it kicks in, the throttle slams shut for a second or so. I only notice this if flooring it around a corner. You can turn this off, but that increases the risk of blowing the differential clutches.

Stabilitrack operates through the ABS system, not through torque management. Really seems to help on those icy traffic circles in the winter.

 

u can disable stabiltrack by holding down the t/c button down for 5 seconds.

 

Interesting. Three times I have experienced this. One time I hit a small bump in the road at load speed under heavy acceleration and it cut out on me. Another time I got on it a little at low speed on a sharp corner (I was almost done with the turn). The other time I was cutting across a couple lanes of freeway to get past a WRX that I had clearly outclassed in the acceleration department, and it cut off the power for a second and I lost my momentum! I was able to catch back up but ran up to traffic so I could not complete the pass. (all allegedly of course)

How do you turn off differential score protection? (I have HPTuner)

OK thanks. Maybe I should RTFM - I bet that is in there.

 

You really don't want to turn it off. You can scale down TM but if you turn off DSC you will be spitting out clutches and half shafts going around turns with too much throttle and you won't even realize it. And maybe you should crack open the tranny case, the car shouldn't engage DSC when switching lanes on the freeway. DSC engages when you try to go around a tight corner with the wheels turned at an aggressive angle with the throttle pinned...the throttle with snap shut and you will get intermediate bursts of WOT, also know as "peg-legging."

 

I always wondered why mine did this in the very same fashion!