5.7 TPI Stumble Only in Drive
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Joined: Jul 2021
Posts: 79
Likes: 61
From: Janesville, WI
Car: 1989 Trans Am GTA
Engine: 5.7 TPI
Transmission: 700R4
5.7 TPI Stumble Only in Drive
Hi all -
I have a stumble in my 5.7 TPI, it only occurs when it's in Drive it seems.
The car has a freshly cleaned MAF, clean air filter, new plugs and wires, new valve seals and relatively new injectors.
I'm thinking possibly IAC? Maybe TPS?
I can pull the IAC out, if I don't adjust it while out, I can insert without relearning, right? I'm wondering if it's just dirty.
My thoughts are a vacuum leak would probably happen all the time, not just in drive.
Thoughts are appreciated. Thanks!
I have a stumble in my 5.7 TPI, it only occurs when it's in Drive it seems.
The car has a freshly cleaned MAF, clean air filter, new plugs and wires, new valve seals and relatively new injectors.
I'm thinking possibly IAC? Maybe TPS?
I can pull the IAC out, if I don't adjust it while out, I can insert without relearning, right? I'm wondering if it's just dirty.
My thoughts are a vacuum leak would probably happen all the time, not just in drive.
Thoughts are appreciated. Thanks!
Supreme Member
Joined: Feb 2005
Posts: 2,508
Likes: 201
From: Hawaii
Car: 89' Firebird / 87' Formula
Engine: 3.4 / 5.0
Transmission: 700-R4
Axle/Gears: 3.42 / 3.42
Re: 5.7 TPI Stumble Only in Drive
I had similar issues... I changed the fpr and that helped although it did not get rid of the problem completely.
Joined: Oct 2001
Posts: 12,216
Likes: 1,141
From: Il
Car: 1989-92 FORMULA350 305 92 Hawkclone
Engine: 4++,350 & 305 CIs
Transmission: 700R4 4800 vig 18th700R4 t56 ZF6 T5
Axle/Gears: 3.70 9"ford alum chunk,dana44,9bolt
Re: 5.7 TPI Stumble Only in Drive
Its rarely the iac, not saying its not it but its rare
Joined: Dec 2004
Posts: 16,752
Likes: 996
From: Mile High Country !!!
Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Re: 5.7 TPI Stumble Only in Drive
Have you done a tps sweep to check for an open in the tps signal from tps ?
Member
Joined: Jan 2008
Posts: 329
Likes: 99
From: Mint Hill, NC
Car: '90 Formula '88 GTA
Engine: 305 TPI 350 TPI
Transmission: T5 700R4
Axle/Gears: 3.42 10 Bolt 3.27 9 bolt
Re: 5.7 TPI Stumble Only in Drive
Check fuel pressure, if the pump is going bad it can bog hard under load (when in gear for example)
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