Cyl 5 misfire - changed spark, coil and injector, what else?

[ajck]

I've got a 2002 S60, UK right hand drive, 2.0T. Cylinder 5 misfire being reported (code P0305), and car stutters and coughs when accelerating or going up hill and there's a small vibration when engine is in neutral (idling). Engine light is also on all the time, and twice while driving it has flashed a few times. I've tried a new spark plug and injector coil on cylinder 5, then swapping the fuel injectors between cylinders 4 and 5. Didn't make any difference to the problem.

Car is also reporting error codes P0132 (O2 Oxygen Sensor Circuit High Voltage (Bank1, Sensor1)) and P0805 (Clutch Position Sensor Circuit) and previously reported P0808 (Clutch Position Sensor Circuit High) but that's gone now.

Any advice or suggestions on how to proceed please? I would love to avoid an expensive trip to the repair garage!

Also, I was wondering if I had correctly identified the cylinder order? I am assuming 1 is closest to the belt on the left hand side and 5 is on the right? (see pic)



Thanks

[reggit]

You’ve got the order correct.

Have you tried a compression test to make sure the engine is healthy?

[Brendan W]

Five is at the clutch end. What did the old spark plug look like coming out?

[oragex]

Here's how to find which cylinder has the actual issue. It is safer to unplug the injector, instead of the coils https://www.youtube.com/watch?v=fnYUQh23p7Q

[GreenBrick]

If the problem remains with the cylinder after swapping the obvious bits then time to look at the electrical connections for the coil and injector, or its a mechanical failure in the valves etc.

Have you done a compression check on all cylinders?

[pierremcalpine]

Did you replace the o2 sensor? I'd be seriously tempted to do that first.

[ajck]

Thanks, so if I do a compression test and shows low compression on cylinder 5, how do I fix/replace the electrical connection or valves?
I've confirmed it's not the spark plug, ignition coil or fuel injector and that it is definitely cyl 5.

Originally Posted by GreenBrick

If the problem remains with the cylinder after swapping the obvious bits then time to look at the electrical connections for the coil and injector, or its a mechanical failure in the valves etc.

Have you done a compression check on all cylinders?

[reggit]

If you get a low compression reading, it indicates a mechanical problem inside the engine. You’ve got a reasonable repair job on your hands. Hopefully it will show no issues and you’re left chasing an electrical issue. Compression test isn’t hard to do on a petrol engine.

Not sure how the ignition system is arranged on a petrol v70. Are you able to take the offending plug out of the cylinder but still connected to the coil? If so, lie it on top of the engine, with the hexagonal bit resting on some of the engine metalwork (earth), spin the engine and have someone check to see if it sparks.

[Geoff moore]

Some cars (mainly french) you have to use diagnostic equipment to tell the engine that you hAve 'cured' the mis fire by cancelling the codes usually car specific and obd squit a drop of oil into the bore of the offending no 5 if the compresion comes up (after a dry test) then it's a piston problem if not then a head problem

[barrybritcher]

Being a white block turbo (they run hot) I would hedge my bets on the coil wiring being heat damaged with insulation cracked causing a short circuit.

Peel back an inch from the coil multi plug and inspect.

It is possible to buy the entire 5 plug harness from Dave Barton (google) form the USA for approx £150-£200. I wouldn't recommend chopping out the bad section and splicing in as you go because another part of the harness will be damaged six months later - it's far wiser to spend the cash once only.