VE Misfire on 3cyl after service

[Vyper]

Hi my friend just brought a 07 Lumina 3.6ltr. It was running perfectly but he wanted to give it a service so he changed the plugs, coils n manifold gasket. After that it was misfiring so he called Lube mobile. Mechanic said it was the PO303 error so replace coil 3. He decided to go with Bosch coils next and replaced all 6 again, but now it's misfiring the 2,3,5 cylinders.

Yes 2,3,5 NOT 1,3,5.

Mechanic is scratching his head as everything is reconnected properly. My mate knows alot about VE's and has always worked on his cars and he can't figure it out and has asked me to see if I can hopefully find the solution for him somewhere.

 

[lout]

usually faulty leads or plugs will cause a coil failure
has he determined if it is spark or fuel that is missing
has he double checked and triple checked each lead is connected correctly

 

[RossK]

Vacuum Leak - manifold gasket not sealing?

 

[Vyper]

He's replaced coils 2x now, plugs 3x, there's no leads on this motor. He's retested the spark this morning and now he's not getting much spark at all. Very weak. And now he's lost cyl 4 ‍

Wades had a few VE's and done work on all of them. He's never come across this before.. He lives up central coast and he too far to drive to his mechanic, and can't afford a $500 tow and has called Lube Mobile 2x now and they are stumped also.

 

[Vyper]

Vacuum Leak - manifold gasket not sealing?

2 New gaskets and both were sealing. And he's tested for vac leak and it's not that. Or fuel pressure.

 

[krusing]

Check the Plugs that go to the ECU, that is located to the left of the alternator/engine [looking at the car from the front]
[which is the drivers side] ,
in case they have dislodged, they do have locking arms.
Otherwise, check the whole loom from the coils to the ECU.
And/Or
get it scanned, as it will have produced DTC's.

 

[redvxr8clubby]

Do you still have the original coils and plugs? Reinstall them and see if any difference - it was running smooth before change try reverting back to original. Otherwise is there any possibility something happening with the wiring loom connection to the coil - bad connections, perhaps individual wire connections within the wiring loom plug body not making good connection now, or wires fractured in the loom - when the connector was removed was only the plug body used to disconnect, or were wires pulled instead of the plug body? I haven't worked on these engines with coil on plug, so I haven't had hands on with these myself, but it's sounding like connections going bad after being disturbed.

 

[syked]

Have you checked the wiring loom behind the manifold near the firewall?

Is he 100% sure he hasn't connected something incorrectly when he reinstalled the manifold?

 

[greenacc]

Is he 100% sure he hasn't connected something incorrectly when he reinstalled the manifold?

This is a possibility. The plastic tube that runs around the back of the manifold to the pcv valve can crack or get crushed under the manifold. It runs really bad when that tube is broken

 

[bazz61]

try swapping battery , my later model used to run rough when unused for a few days , new battery fixed it, I guess the computer magement system