'04 4.6lt Quad Cam FI Supercharged Intercooled engine issue

[Cobra]

Hi all,
First post on this site. Thanks to all who contribute.
The issue is that an '04 4.6lt FI Supercharged Intercooled Mustang engine fitted to a Cobra replica (owned by a friend of mine) is not firing on one bank of cylinders.
Originally the car had overheating issue while involved in Club racing that was finally traced to a faulty radiator cap.
However in the process of trying to find the problem, and then the dead bank of cylinders issue, a range of things was tried eg compression test; coil test; plug pack test; fuel pressure test; fuel flow, injection loom, etc with no significant bad results
The bank of cylinders closest to the fuel pump is the one still working while the bank furthest away from the pump is not - although opening up the fuel rail on the dud side, shows plenty of fuel.
The other weird thing is that the dud bank seems to work at higher revs on the road.
Does anyone have a clue as to what to look at next?
Cheers, Roger

[hybrid]

Have you put a test LED on the injector plugs to check that the injectors are getting a signal while the engine is running?

You can just get a 12v rated LED, or a normal LED with a resistor on it and stick the legs down into the injector plugs... if you can get to them.

[Cobra]

Have you put a test LED on the injector plugs to check that the injectors are getting a signal while the engine is running?

You can just get a 12v rated LED, or a normal LED with a resistor on it and stick the legs down into the injector plugs... if you can get to them.

Hi Hybrid, thanks for your reply. Yes we have good spark right to the plug - and new plugs

[hybrid]

Not spark... injectors.

[Cobra]

Sorry, yes I can confirm the injectors were removed, checked and replaced and an auto elect has confirmed injectors are getting a signal.

[hybrid]

Ok, so there's only 3 things that will stop an engine firing.
Compression, spark (at the right time) and fuel.
If all those are present, it will fire.

The fact that it works at higher RPM would suggest something electrical to me.

Was the fuel pressure checked on both sides of the rail?

[Cobra]

Thanks for the suggestion, I'll check whether the fuel pressure was checked both sides of the rail.

[jas24zzk]

Quad cam huh...hmm

Hasn't dropped a cam belt/chain??

[Cobra]

Hi Hybrid, you were right on the money suggesting something electrical, as an auto elect found a broken wire leading to one of the injectors on the dud bank.
It seems that one injector being out means the computer won't let any injector work on that bank.
At higher revs, the broken wire worked well enough to let the computer fire all the others in the bank.
Thanks for your help, it is really appreciated.
Cheers, Roger

[hybrid]

Great news, glad to help!

[hybrid]

Quad cam huh...hmm

Hasn't dropped a cam belt/chain??

That crossed my mind too, but then it wouldn't have fired at all, no matter what the RPM.