[RL14HER]

So I’ve got an n43 with cold start and random idle Misfire on cylinder 4. Plugs and coils changed still there. Injectors all replaced with index 11 3 years ago. My question is before I go about looking at injectors again, can something like nox/o2/crankshaft position/knock sensors causes individual cylinder misfires or would they be random misfires in any cylinder.

Thanks

[jwilalex]

N43 is very sensitive unfortunately, other possible causes are the intake/exhaust camshaft sensors, an elongated or stretched chain (possibly due to weak tensioner) or worst case both the vanos hubs. Also if you have Boche spark plugs in then that's a big no no as they are different in size/length to the OEM NGKs.

[RL14HER]

Would these causes be a single cylinder misfire or multiple cylinder misfire. I would have thought that a single cylinder misfire is going to be down to coil, plug or injector? But what I’m not sure about is if these other causes can also cause a single cylinder misfire?

[jwilalex]

Easy check is swap plug and coil from cylinder 4 with the set in 1 and see if it follows; if it does easy fix. If you have ability swap injectors around but I’d be surprised if they’ve gone after 3 years.

You could try the traditional Italian tune up with some cleaner/additives in the tank. A knackered NOX sensor will cause problems but rule out the others first.

[RL14HER]

Done all of those aside from swap injectors. I think it’s time I give in a pay for some proper diagnostics

[aaronblack]

Originally Posted by RL14HER

Done all of those aside from swap injectors. I think it’s time I give in a pay for some proper diagnostics

Swapping injectors really isn't hard so long as you have inpa/ista and tools. Of course if you don't want to do it that's a different case.

Have you checked your sparks to see if they show signs of leaky injectors? This should be first prior to swapping injectors.