Need Help! 91 Vn Running Rough!

[MikeC]

If your buying sensor or control system parts get GMH/GM/Delphi. I just spent $133 for a speed sender that was supposed to be equivalent to the GMH original from a reputable supplier- it looked the same and worked the same around Melbourne but on long trips it threw a code 24. Replaced it with an old, second hand, original GMH sender and the code went away.

 

[Jimmee]

I tried to bridge the ALDL but it just leaves the eng light solid doesn’t flash whatsoever. So I Started stuffing around with the injectors when I noticed cyl 5 and cyl 2 aren’t firing at all I can disconnect the injector/s and doesn’t affect how it runs. So I took the injectors off cleaned them out and switched them around. And The same cylinders still aren’t firing, thinking it would have to be valves if anyone has any ideas that would be much appreciated. Cheers

 

[MikeC]

Did you check the ALDL with the engine stopped? If everything's OK it should flash a code 12.
Maybe the wiring's damaged that pulses 5 and 2. The ECM and EFI relay should give the injectors 12V pulses.

 

[Jimmee]

Yeah I bridged it then just turned it over to reds and it just stayed on, done that a couple times but still nothing so started it up and nothing either. I have tried to look for damaged wiring but everything is pretty good, had an auto electrician out to look at it. He thought it was DFI module and coil packs. But have since replaced all that and new injectors this arvo. Still no good

 

[MikeC]

Try clearing all codes by disconnecting the battery for a few minutes. The two plug ports you connect in the ALDL are both on the extreme right looking at the plug with the connector clip down- the wires from the ports are black and white/black. I connect them with a bent paperclip.
If the engine light is on all the time you probably have a short on the brown/white wire between the check engine light, the ALDL socket and terminal A9 on the ECM. My guess is this short will lock your ECM into field service mode with the ignition fixed to fire permanently at 10 degrees BTDC.
Try,with the battery disconnected, to measure the resistance from the top 2nd port from the right on the ALDL plug ( brown/white wire) to earth. If its a low resistance reading the brown/white wire is shorting out somewhere.

 

[woteva]

On the VN V6, all injectors fire at the same time so if you replaced the injectors the fault must be in the wiring if they are not working
Have you checked spark is good on the 2 suspect cylinders ?

 

[Jimmee]

Yeah there is definitely good spark there, the injectors do still tick as do the rest. So I assume the wiring is alright as it seems to get all injectors going. Its spraying plenty of fuel out the exhaust aswell

 

[VN Woody.]

G’day I’m new on here, but have you given the engine a compression test? Having fuel coming out of the exhaust tells me you have valve issues. Also you can place a bit of cardboard over the tail pipe and it shouldn’t pull it back in causing a pop sound. An old trick my dad taught me.

 

[Jimmee]

Alright mate I’ll give that a go and see what it does, but yeah I’m thinking it’s gotta be valves have done everything else I can think of. An no I haven’t tested the compression. Thanks

 

[MikeC]

A vacuum gauge will generally identify valve problems: https://www.google.com/url?sa=i&url...ved=0CAkQjhxqFwoTCPjk_7_FkuoCFQAAAAAdAAAAABAE