Hi guys,

Have 170k on my DD but in the last 20-30k I've noticed that during a 4-3 downshift, I feel the tranny downshift, but there is a secondary "bump" that occurs...sometimes rather harshly. Have to verify if this also happens during a 3-2.

I believe it may be a timing issue between the convertor unlock and the actual downshift? Might have the sequence backwards also, i.e. unlock then downshift.

Would a tuner help troubleshoot or would it just show that the computer "told" the tranny to downshift?

Hard to explain what I'm feeling.

Thanks,

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04 Comp G, my DD - Wizair, 180 T-stat, W body DP, 18" Verde 5ives ---> 170,000 and counting!

I have experienced the same thing, still don't know exactly what it is or what caused it, but I ended up cleaning my MAF and it seemed to help reduce how noticable the "bump" is. I even had a fellow mechanic take a test drive with me and he thinks it has to do with either the MAF being bad or even the TPS, but I haven't gone as far as to replace either yet.

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Mods so far: Intake, 104's, 180*, Overkilled 4.0, Alt. Re-wire and voltage booster, F&R STB's w/DR's brackets, GMPP front sway w/poly links, TA's, HID's, Tints, 3.6 MPS, AF scan gauge, boost and oil pres. gauge, upper poly mounts, f-body upgrade, D/S rotors, SS hoses.

I can believe that depending on how much throttle is applied, the TC unlocks first, and then, the actual 4-3 downshift.

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One Big Ass Mistake America

You may be onto something regarding the MAF, that can cause all kinds of funky issues. I'll clean it today and post back.

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04 Comp G, my DD - Wizair, 180 T-stat, W body DP, 18" Verde 5ives ---> 170,000 and counting!

Ok, cleaned the K&N, MAF and throttle body. Still the same. The more I concentrate when I drive it, the more I believe it is a downshift/torque converter issue...

Damn, need a tuner.

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04 Comp G, my DD - Wizair, 180 T-stat, W body DP, 18" Verde 5ives ---> 170,000 and counting!

I get this "bump" once the trans gets up to temp. Mine happens when I am slowing down from say 40-0mph. The car will "bump" at exactly 7mph everytime.

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04 Comp G. Sport Red. SPO.
SmoothFlow 3.6MPS | PRJ Tune | Powerlog | 3" DP | Wizair | PRJ 10.4mm wires/Autolite 104's

I only experience something like this in TAP mode... i know for sure that it will shift 1st once you hit 5 mph slowing down.

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HID's(8000K Dims),K&N Air Charger,LED tailights,STB's F&R with Don's brackets,Custom Catback.

Yeah, MidwestSpecial...what you are describing is the downshift to first gear.

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One Big Ass Mistake America