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Gary, Australia Car Mechanic
Category: Australia Car
Satisfied Customers: 890
Experience:  Senior Technician
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Have a vz v6 and replaced the engine and now it cranks and

Customer Question

Have a vz v6 and replaced the engine and now it cranks and wont start but back fires what could it be
JA: Have you checked the engine's fuel supply? And the spark plugs -- are they all working?
Customer: Am about to replace the plugs and coils. Haven't got any way to check fuel but if i push down one the valve at the back of the engine some comes out
JA: What is the make/model/year of your car?
Customer: Is a holden vz sv6 ute 2006
JA: What year is your Holden?
Customer: 2006
JA: Are you fixing your vehicle yourself? What have you tried so far?
Customer: Yeah am trying just pulled the intake off to replace spark plugs
JA: Anything else you want the mechanic to know before I connect you?
Customer: I replaced the engine
Submitted: 7 months ago.
Category: Australia Car
Expert:  Gary replied 7 months ago.

Hi there,

Did you use the original ECM when you swapped the engine?


Customer: replied 7 months ago.
I use the on from my vehicle
Customer: replied 7 months ago.
I also have replaced the coils and plugs but hasn't change anything
Expert:  Gary replied 7 months ago.

Ok, if everything connected on the engine , including the crank sensor?

Do you have access to a decent scan tool, like a Tech2?

I would be checking engine speed data on Tech2, no engine speed while cranking will give no start.


Customer: replied 7 months ago.
Also replaced the crank angle sensor but i dont have access to a scan tool
Expert:  Gary replied 7 months ago.

All the grounds are connected on the cylinder heads?

We need to get a scan tool.

My bet is you have no spark and injector pulse.


Expert:  Gary replied 7 months ago.

Hi again,

Do you need any further help?

I hope my advice has been of assistance to you.

Kind regards


Customer: replied 6 months ago.
I have had the vehicle checked by a mechanic. They tested spark, injector pulse, compresion and fuel and are all ok. Have just found out that the wiring loom and sensors has to be the original ones from the engine i removed.
Customer: replied 6 months ago.
I havnt done it yet to see if it has solved the problem as im flat out with work
Expert:  Gary replied 6 months ago.

Yes, the harness needs to match the vehicle and PCM.

Original harness.

Your mechanic says everthing tests ok, so it should start.

Is the donor engine earlier than the original?


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