2004 vz misfiring

[Habby18796]

Hey guys need some gurus help, been trying to diagnose my car myself to save some dollars..

So my 2004 vz alloytec randomly started to run like crap after driving along the highway, after coming to a stop at home it was idiling pretty rough, I checked the car the next morning and started Fine etc, after driving it for about 10-15 minutes it began to misfire again… I then began my diagnostic side of things by checking coil packs… I came across bank 3 coil pack being faulty and not working… I then replaced it with a new coilpack… car started and drove fine about about another 10-15 minutes and the misfiring came back but was intermittent misfires wasn’t consistent… then eventually it came back as before and became consistent … I then Began to check coils again and some how it was the exact same one… I then changed spark plugs and gapped them to 0.7 as recommended by my mechanic and switched coilpacks over with a different one… then after the misfiring has just become consistent from start up and still from bank 3 the coil unplugged is making no difference… I then began to dig deeper and changed the injector around to see if it switched which coil it would misfire from and still hasn’t made any difference…. I’m lost in what I have to do right now…. Car was running absolute perfect till now… please help

 

[Fu Manchu]

Get a scan tool onto it to find out more.

 

[ephect]

If changing coil and injector from 3, then it is possible wiring issue

 

[Cozwuna]

Hey guys need some gurus help, been trying to diagnose my car myself to save some dollars..

So my 2004 vz alloytec randomly started to run like crap after driving along the highway, after coming to a stop at home it was idiling pretty rough, I checked the car the next morning and started Fine etc, after driving it for about 10-15 minutes it began to misfire again… I then began my diagnostic side of things by checking coil packs… I came across bank 3 coil pack being faulty and not working… I then replaced it with a new coilpack… car started and drove fine about about another 10-15 minutes and the misfiring came back but was intermittent misfires wasn’t consistent… then eventually it came back as before and became consistent … I then Began to check coils again and some how it was the exact same one… I then changed spark plugs and gapped them to 0.7 as recommended by my mechanic and switched coilpacks over with a different one… then after the misfiring has just become consistent from start up and still from bank 3 the coil unplugged is making no difference… I then began to dig deeper and changed the injector around to see if it switched which coil it would misfire from and still hasn’t made any difference…. I’m lost in what I have to do right now…. Car was running absolute perfect till now… please help

I had exact same issue mine was problem with ecu

 

[wildfiremaint]

If injector doesn’t get 12v or any pulse from the ECU, then its ECU or wiring.
You will have to trace it by back to ECU or
12v source that supplies each of the injectors.

 

[bcw61]

I hate to say this, but with all the fault-finding steps you have already taken, this is really smelling like a wiring issue in the ignition coil circuit or an issue in the ECU.

 

[DavesSV6Tonner]

I hate to say this, but with all the fault-finding steps you have already taken, this is really smelling like a wiring issue in the ignition coil circuit or an issue in the ECU.

Agree, ECU.

 

[lout]

might be time to have a professional check it over

 

[wildfiremaint]

Agree, ECU.

ECU to Injector wiring. Difficult to do as you have to work out which pin amongst
the dozens of pins in the ECU plug.

 

[Fu Manchu]

I saw a case of an injector not firing because of damage to a reluctor wheel. No injector signal. Wasn’t the ECM. Was a missing tooth on the reluctor wheel. So it was found after many other workshops threw parts at it. Lots of dollars. One guy did a proper look and found the cause of a lack of signal to the injector was caused by the missing tooth giving wrong data to the ECM and confusing TDC data.