Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.

New Posts Contact us

Just Commodores Forum Community

It takes just a moment to join our fantastic community

Register

Vt 3.8 missfire

Jack pollock

New Member
Joined
Feb 10, 2019
Messages
2
Reaction score
0
Points
1
Age
25
Location
New Zealand
Members Ride
Vt commodore 3.8 ecotec
So I have just finished a motor swap put everything back together starts and idles fine. So I took it for a drive and it backfires out of the exhaust and shudders and struggles when giving it gas then when you stop it dies any ideas??
 

Brysha89

Active Member
Joined
Dec 9, 2018
Messages
329
Reaction score
45
Points
28
Age
34
Location
Melton,Victoria
Members Ride
WM Statesman L98 6.0ltr
Check all Vacc hoses at the back of the engine are connected if so then the flywheel is miss aligned were the engine connects to the torque converter and gearbox did a engine change last year in a old VX i had i had the same problem after install but mine was a vacc hose and it will need a tune as your ecu is tuned to the old engine.
 

Jack pollock

New Member
Joined
Feb 10, 2019
Messages
2
Reaction score
0
Points
1
Age
25
Location
New Zealand
Members Ride
Vt commodore 3.8 ecotec
The motor and gbox were complete never been separated and I have checked all the vac lines they are all in the right place
 

Brysha89

Active Member
Joined
Dec 9, 2018
Messages
329
Reaction score
45
Points
28
Age
34
Location
Melton,Victoria
Members Ride
WM Statesman L98 6.0ltr
well if all vacc hoses at the back of the engine are on, i don't need to ask about the front, it would definitely need a ECU tune as when i installed my ecotec to the VX i had shuddering too i thought it would be ether a engine or gearbox mount took it to my mechanic he said it needs to be tuned to the engine thats what is causing Struggling, back fire and shuddering after a certain speed.
 

Brysha89

Active Member
Joined
Dec 9, 2018
Messages
329
Reaction score
45
Points
28
Age
34
Location
Melton,Victoria
Members Ride
WM Statesman L98 6.0ltr
Unless there is more sinister noises from the engine besides the shuddering that will set you back an hours work at a mechanics and cost me 150 for the tune so dont pay more than $300 for a mechanic to get it right .
 

_R_J_K_

Well-Known Member
Joined
Dec 20, 2008
Messages
6,723
Reaction score
1,856
Points
113
Members Ride
Zenki S14
it will need a tune as your ecu is tuned to the old engine.

No it won't, in terms of engine management all Ecotecs are effectively the same. Would really love to know what 'tuning' this mechanic did for $150.

OP, I'd do basic service stuff first if you haven't already and don't have a history on the engine. Plugs, leads, the obvious stuff.
 

Brysha89

Active Member
Joined
Dec 9, 2018
Messages
329
Reaction score
45
Points
28
Age
34
Location
Melton,Victoria
Members Ride
WM Statesman L98 6.0ltr
No it won't, in terms of engine management all Ecotecs are effectively the same. Would really love to know what 'tuning' this mechanic did for $150.

OP, I'd do basic service stuff first if you haven't already and don't have a history on the engine. Plugs, leads, the obvious stuff.
I'm No Mechanic i was told that by my last mechanic as i did an ecotec engine swap and had exact same problem as the first post by jack pollock, when i changed the engine plugs and leads were new when i installed it had the shuddering, lack of power at certain speeds and my last mechanic told me just needed to be tuned . Now i dont go to any mechanics now i can self diagnose with my scan tool but that was what i was told the last time i did and ecotec engine last year, i now own a super 6 vt and LS1 Statesman.
 

_R_J_K_

Well-Known Member
Joined
Dec 20, 2008
Messages
6,723
Reaction score
1,856
Points
113
Members Ride
Zenki S14
Well whatever he did, it wasn't a tune, not for $150. It's not something you can just go down to the local for, and it costs a lot more from reputable shops.

Shoulda asked him for a dynograph.
 
Last edited:

VT2Commie

Well-Known Member
Joined
Jan 1, 2018
Messages
435
Reaction score
289
Points
63
Location
WA
Members Ride
VT2 Clubsport R8
Something was damaged in the engine swap for sure. Knocked and cracked something. Stretched or pulled something. Broken cracked sparkplug, coilpack, etc. stretched/pulled spark plug lead/s, electrical harness. I could keep going but you get the drift. Check everything again and then physically check it again. Did I say check everything again? Yeah I did, check everything again.
 
Top