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Thread: Turbo Cavalier 4T45E questions!

  1. #1
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    Turbo Cavalier 4T45E questions!

    I have a 2000 Cavalier with a 2.2 ecotec/4t45e swap and Cobalt SS turbo setup on 8 pounds. I got the car already modded like this and was told it needs a tune as the "tune" that's on the car is bone stock. I have issues with driveability and the car bogs a lot unless it's over 3/4 throttle.

    1. Taking off from a start....car shifts from 1st to 2nd almost immediately. Shifts flare.

    2. Cruising around 40, the transmission shifts into overdrive, but if I lift off the throttle it will drop out of overdrive.

    3. Roll into the throttle and the car will bog heavily.....more throttle and it feels like the engine is kinda farting and popping, roll into it more and the trans will downshift, tach will go to about 4500 and the car will rocket off like crazy.

    4. Sometimes if I nearly floor it from a lower speed....maybe around 30-40 mph, it will downshift like above, however it bounces as if it's on the limiter and won't upshift. I've never had this happen at interstate speeds: 50 and above.

    5. Once in a while the transmission will not shift out of 3rd gear (I think)....there's normally a distinct upshift at 40 mph, however when it's acting up it will not shift at 40 and just continue to stay in that gear....then I'm turning 3K or higher at 60 MPH. I think it's related to the remote unlock or something because I've played with the remote while this is happening and sometimes it will start to shift again. Sometimes if I let it sit for a while it will be fine. Dropping the shifter from drive to 2nd or 1st does absolutely nothing. This issue usually occurs after I drive a short distance and then stop for gas...go inside, pay, pump the gas and drive off.....the transmission shift crisper and the car feels a lot livelier but it won't shift out of 3rd.

    I just want to know if this is something that is known and if it's an issue with the stock tune....

  2. #2
    Advanced Tuner Dr. Nopps's Avatar
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    Please post a copy of your tune and a scan of it doing this. The bogging part sounds a little like what happens when you don't have large enough injectors or when they start to go bad, and also the resulting effects of running a turbo setup on a stock Cavalier tune. The 3rd gear hang up could even be caused by cracked/broken metal tranny pressure lines inside the pan, if it's the right line and no codes are popping up. But those are just some possibilities, can't tell if your tune is causing this without posting. Also you're calling it a 2K Cav 2.2 Eco/4T45E swap, what was swapped? As far as I knew they already came with that engine and transmission available. Was this a 4T45E transmission from a different vehicle, with a potentially different drive sprocket ratio? No stock tune using a 4T45E has ever done this on me in the past though.
    Last edited by Dr. Nopps; 04-03-2015 at 05:17 AM.