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VZ Alloytec V6 not firing on one bank

PeterC

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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).
 
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Not_An_Abba_Fan

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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

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There is two earth points. One on each side on the cylinder head.
 

PeterC

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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
 

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Power will get to the connector, but does it earth through the harness?
 

PeterC

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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

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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

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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.
 

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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

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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.
 
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