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

VZ Alloytec V6 not firing on one bank

PeterC

New Member
Joined
Feb 24, 2018
Messages
13
Reaction score
2
Points
3
Age
57
Location
Canberra
Members Ride
VR
My son rebuilt his V6 and it starts and runs but really roughly and it seems as if only one bank is firing that is; warm exhaust gas from one pipe and cold gas and manifold from the other bank. Any ideas why this could be? I kind of suspect the loom might have been damaged during rebuild or perhaps the injectors are fused left and right. (I believe it is).
 
Last edited:

Not_An_Abba_Fan

Exhaust Guru
Joined
Aug 18, 2006
Messages
14,079
Reaction score
605
Points
113
Location
Bunbury, WA
Members Ride
Strange Rover
Check the power supply to each bank and the earths. The injectors have constant power and are fired by the PCM earthing them.
 

Fu Manchu

Well-Known Member
Joined
Mar 18, 2006
Messages
4,093
Reaction score
1,924
Points
113
Location
WA.
Members Ride
Slug powered VZ, Cross 8 VZ, VE Calais & ya mum.
There is two earth points. One on each side on the cylinder head.
 

PeterC

New Member
Joined
Feb 24, 2018
Messages
13
Reaction score
2
Points
3
Age
57
Location
Canberra
Members Ride
VR
Checked fuses ok and power gets to connector. All seems good, i guess could be an issue after plug. Could also be a vacuum leak as no power breaks. Would the ecu shut one bank down? Can't get to injectors with running engine..... very poor
 

Fu Manchu

Well-Known Member
Joined
Mar 18, 2006
Messages
4,093
Reaction score
1,924
Points
113
Location
WA.
Members Ride
Slug powered VZ, Cross 8 VZ, VE Calais & ya mum.
Power will get to the connector, but does it earth through the harness?
 

PeterC

New Member
Joined
Feb 24, 2018
Messages
13
Reaction score
2
Points
3
Age
57
Location
Canberra
Members Ride
VR
I thought it earths through the ecu, I am not where the car is so difficult to check. It went to a mechanic and he didn't know what the problem was - we assume his scan tool was better. Does the ecu shutdown a whole bank if the timing were a little bit out?
 

shane_3800

Well-Known Member
Joined
Aug 13, 2011
Messages
1,392
Reaction score
351
Points
83
Age
32
Location
places
Members Ride
vr commo
I'll bet it's the earth for the injectors. I know this because it's happened to me before and one of the old guys at work laughed because it happened to him too. It takes about 30 seconds to do the bolt up, it's got a 10mm hex and it's a 6mm bolt about 15-20mm long with a flange head.
 

PeterC

New Member
Joined
Feb 24, 2018
Messages
13
Reaction score
2
Points
3
Age
57
Location
Canberra
Members Ride
VR
I'll try to get back to the car on the weekend, thanks. Does this mean there are two earths, one for each bank? My son is very upset given the amount of work he put in.
 

shane_3800

Well-Known Member
Joined
Aug 13, 2011
Messages
1,392
Reaction score
351
Points
83
Age
32
Location
places
Members Ride
vr commo
I'll try to get back to the car on the weekend, thanks. Does this mean there are two earths, one for each bank? My son is very upset given the amount of work he put in.
Yea two earths one for each side and when disconnected it will drop one bank.
It's pretty obvious for a mechanic as it comes up with either 1, 3, 5 missfire bank 1 or 2, 4, 6 missfire bank two. First thing you do when these codea come up is inspect the bank not firing and it stands out like dog balls that there is a earth wire well it's like 3 or 4 all crimped onto the same terminal hanging near the exhaust.
 

Not_An_Abba_Fan

Exhaust Guru
Joined
Aug 18, 2006
Messages
14,079
Reaction score
605
Points
113
Location
Bunbury, WA
Members Ride
Strange Rover
That is the harness earth for coils, not the injectors. Injectors are constant power and fired by the ECU triggering earth. There is no ground wire for the injectors, they are fed power and the ECU fires them. So if that earth is the issue then the coils will not be firing on that bank.
 
Top