Last Monday I took my car to a large shop to be tuned by a respected tuner that is well known. An employee of the company placed the car on the dyno-wheel and worked the tap-shift feature during the pulls. The tuner was in the car for the first run and stood outside for the other runs. The first three pulls went OK with the performance of the car slowly being increased. However, there was an issue concerning the TC locking and unlocking. On the fourth pull I heard the car go through the gears to third and then they went WOT. At the very end of the pull I heard the car jump in rpms like crazy!!! The car was screaming. It was like a manual being put into neutral and then the gas pedal being pushed to the floor.
The tuner said that right after the pull, the car downshifted into second gear all by itself. He could not offer any explanation of this event. According to what I saw on the graph the rpm went off the screen and the speed of the car was around 137 when it was downshifted.
The car was towed home and we have removed the front head. We have done a seal test with two of the cylinders failing. This is as far as we have gone. We are trying to determine what to do next.
I have spoken to a really good transmission guy about the downshift event, the TC locking and unlocking and the TC being locked up during the 4th run. I will be contacting the TC Company next week.
The tuner has sent me 4 files, but I am unable to open 3 of them because they are HPTs and I don’t have the software.
Can anybody out there give me a hand with this situation? The shop will not return my phone calls, and the tuner was out of town last week, so I am hoping to hear from him this week.
I can forward the files to you via email.

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2006 GXP almost finished! I/H/C/E, TEP w/3.29s, small shot

What is strange is that the PCM won't allow a downshift like that. I have to believe that something inside the transmission failed. Even if the shift selector would have been placed in "2," the PCM would have said no.

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One Big Ass Mistake America

this is true in the PCM there is no way it would allow the down shift. the maximum down shift speed to second is 77mph

i got that from looking at a compG trans file

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92 LeBaron Convert: Turbo 3L 97 Grand Prix GT 4dr "Frankenstein": L67 4t65 swap
97 Grand Marquis: Summer DD 99 Grand Prix GTP: Top Swap Beater

That would probably be max speed. Either way, 137mph will never get a downshift to second. I almost wonder if the guy doing the tuning fat fingered something, and screwed up a shift point, or allowance. We need to see those files.

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One Big Ass Mistake America

What is with these bozons?
Your "tuner" screwed up.
As soon as the car started showing issues with T/C locking and unlocking,he should have backed off.
Attach the files to a post.
I'd love to see them.

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2005 GT owner [Non S/C] with a "big DIC".
Two years later and I still love the car.
Thanks Pontiac...Bleen is keen!

yup my bad ment maximum

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92 LeBaron Convert: Turbo 3L 97 Grand Prix GT 4dr "Frankenstein": L67 4t65 swap
97 Grand Marquis: Summer DD 99 Grand Prix GTP: Top Swap Beater

I just received a picture of one of the downloads, peak rpm reached over 8100rpm!

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2006 GXP almost finished! I/H/C/E, TEP w/3.29s, small shot

That engine will be absolutely toast. I don't think I'd reuse ANYTHING off of it.

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One Big Ass Mistake America

yeah that is wow

i would reuse the cam, heads (if the valves did not make contact going that fast may have had valve float), cam, and the block other then that i would not risk any of the parts after being abused liek that. this includes not reusing the valve springs

one thing i want to know how did the neigne even make it to 8100rpm did they have the rev limiter removed?

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92 LeBaron Convert: Turbo 3L 97 Grand Prix GT 4dr "Frankenstein": L67 4t65 swap
97 Grand Marquis: Summer DD 99 Grand Prix GTP: Top Swap Beater

Good questions and thanks for your input. I now have the files in a excel spreadsheet if anybody is interested in seeing them. PM me your email address and I will send them to you.

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2006 GXP almost finished! I/H/C/E, TEP w/3.29s, small shot

Your best bet would be to contact a lawyer since the tuner doesn't want to help you on this matter.

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Bright Red 2008 G8 GT

Mods: DRCUSTOMPARTS Center Gauge Bezel
Superchips ECM/TCM Tune- Volant CAI
Solo Axlebacks - HID's
Holden V8 Badges
My Website

There is a folder in the HPTuners editor called Transmission Diagnostics where you can find a few parameters that restrict gear command. Our STOCK numbers are set at 5500 rpm and 62 mph. The rpm and mph must be UNDER these two parameters to enable gear control. MY current modified file on the car is set at 6200 rpm and 188 mph. Looking at my scan, the mph was at 145 mph, below the 188 requirement, and rpm was at 6050 which is under the 6200 rpm requirement which will allow gear command. This explains not only how it is possible to occur but why guys with stock trans tunes or just ratio changes cannot command a downshift when going over a certain speed.

The TC used in my transmission package is not designed to be locked during WOT. The TC was locked during the dyno testing and could have been damaged. Debris could of then of been throw back into the transmission.

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2006 GXP almost finished! I/H/C/E, TEP w/3.29s, small shot

The TC is outside the trans so there's no way for any debris to get inside if it fails.

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Bright Red 2008 G8 GT

Mods: DRCUSTOMPARTS Center Gauge Bezel
Superchips ECM/TCM Tune- Volant CAI
Solo Axlebacks - HID's
Holden V8 Badges
My Website

actualy debits can go back into the trans as trans fluid is what locks the conveter by flowing in two directions.

it is sounding more and more like a giant clusterfuck of a mess you are in that realy sucks

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92 LeBaron Convert: Turbo 3L 97 Grand Prix GT 4dr "Frankenstein": L67 4t65 swap
97 Grand Marquis: Summer DD 99 Grand Prix GTP: Top Swap Beater

Small particles can flow in the fluid but he made it sound like the TC blew huge pieces into the trans.

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Bright Red 2008 G8 GT

Mods: DRCUSTOMPARTS Center Gauge Bezel
Superchips ECM/TCM Tune- Volant CAI
Solo Axlebacks - HID's
Holden V8 Badges
My Website

Baseball bat justice?

...And this is why I don't let other people touch my stuff. In all honesty though, sorry to hear about his. That's never a fun way to break something, especially if it wasn't YOU that broke it.

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Dubs:00 VW GTI VR6, Low and Slow 91 VW GTI 8v, Shave the Bay!! 91 VW Cabriolet 8v, bitch Basket
GP's:04 GP GT, Past now G-Ma's Girlfriend's 97 GP GT, "Project Pink Power"

you'd be surprised fot he size f the junk that could get in

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92 LeBaron Convert: Turbo 3L 97 Grand Prix GT 4dr "Frankenstein": L67 4t65 swap
97 Grand Marquis: Summer DD 99 Grand Prix GTP: Top Swap Beater

my truck needed a trans flush when the new tranny went in. the torque converter literally exploded so i went w/o one for 4 months until the partials literally clogged the entire tranny cooling system

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any updates on this?!

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2004 White CompG CAI, 180* tstat, 104s, 3.5", Tuned. 0*kr WOT

I have hired an attorney and have filed warrant in debt with the court. Learning to live as a one car family.

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2006 GXP almost finished! I/H/C/E, TEP w/3.29s, small shot

Hope everything works out!!

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2004 White CompG CAI, 180* tstat, 104s, 3.5", Tuned. 0*kr WOT