Why does the tranny shift by itself.

[nastyvr6]

My wife has a 2004 PT GT auto. She has a mbc and a k&n filter on the car it runs fine from a roll. But the problem is when I put it in drive or in the autostick and turn the traction control off and I launch it it leaves hard but when it starts to boost and spin the tires the tranny shifts it to 2nd and it bogs horribly. No matter what I do. Any suggestions

[2step]

Can you give more info on what RPM this is happening at? The trans is programed to self-shift at a set RPM. It's also possible that you're hitting the rev limiter and power is being cut by the PCM.

[turbotouring]

Mine is doing this also.
When the engine RPM reach 6000 the trans shift into
second gear,wheter you're going 5 or 20 MPH.

I found this VERY anoying.

But i try to get on it gently but fast to avoid that.[8)]

[13secPTCruiser]

if you arent running stage 1, the stage 0 computer might sense over boost and put the car in 'suck' mode

[SRG]

Read the manual that came with the turbo, even when using autostick, there are a couple of reasons the transmissions will shift NO MATTER WHAT. First is if it reaches 5600 rpm (I think 5600, check the manual to be sure). Another is if the transmission temp get too high, the training runs as if its in "D", not autostick.

Obviously, Chrysler wanted to protect the transmission.

SRG

[dfunkdj]

I have a 2003 Dream cruiser 2 with stage 1 and mbc and APG WGA mine auto shifts at high RPMs too but it dosent bog it just takes off.

Don

[MichaelDay]

The shift at redline in AutoStick mode is normal and unavoidable. The bogging down after the shift is NOT normal and should be fixed. You should be able to put the GT in AutoStick mode at a stop, feather the fuel in quickly but avoiding unnecessary wheel spin with the lousy stock tires, have it shift by itself at just about 6k then continue to pull hard. Just keep your foot into it while it is shifting. If you try to anticipate the shift and back off the throttle, the computer will get confused as to your intent. If you are using this approach, you have a problem. Unfortunately, it may be a computer problem.

If you are fortunate enough to have a good dealer, tell them it is bogging down when it autoshifts from first to second.

[nastyvr6]

No it shifts in auto stick or in drive once it breaks traction. This also does it with traction control on and off. It shifts at like 3500-4200. I am not sure why. It is also not something I can take it to the dealership for it imagine me going in saying when I punch it and it hits 19 lbs and blows the tires away the tranny shifts itself.

[Hot Wheels]

I think what you are seeing is that at 4200 rpm or so you are losing traction and at that point the engine is revving very quickly to either the shift point in drive or the rev limiter in autostick and then shifts into second. Normally, with good traction, you might shift at 40-45 mph without any bog. When the tires spin, you are only going about 25 mph and the bog occurs because there is too much of a difference between the speed that the car is actually going and what the car's gearing is expecting. If you have any mods that cause you to lose low-end torque, such as a very low back-pressure exhaust system, the bog will be even worse.