Coil Pack minus one lead

[Marky 0]

Is it going to damage the coil pack if I run the engine with one ignition lead disconnected? Presumably a big spark would jump out the coil pack looking for an earth? Sounds dodgy.

My other question is to do with reaching the fuel rail. Can I get access to disconnect any of the electrical plugs to the injectors without removing the upper air intake manifold?

[Marky 0]

My problem is similar to someone elses recent post. One of the cylinders is misfiring. Since the coil pack and leads and spark plugs have been replaced the most likely candidates are:

1. Injector

2. Wiring to ECU

3. ECU

I do have a spare ECU but don't want to disturb the one in the car and I think an ECU fault so it only misfires on one cylinder seems unlikley.

I think the next step is to swap injectors between the bad cylinder and a good cylinder.

BTW: compression check was good, varied between 150 -> 160

[mannie 0]

Check No. 6 plug for wet/dampness.

[Marky 0]

interesting you should say that as no 6 is the one that is misfiring. Before we replaced the leads/plugs the plug lead was covered in engine oil and the spark plug itself was completely covered in black oily gunk and clearly had stopped working.

I had a look just now, its 500 miles since they were replaced. No 6 has the correct colour on the electrodes but there is some oily stuff on the end of the thread. and the thread is 'wet'. but didn't smell of petrol. I took another spark plug out and that had the same colour but none of the wetness or oil.

But this might be a read herring as the tip is in the right condition.

[Marky 0]

Being unsure where to look next I took it for some more diagnostics. They took off all the leads and lubricated the contacts before putting them back. The outcome of this is that the engine runs more smoothly which has made the problem easier to diagnose:

The problem is when the engine is under load it feels like a holding back rather than a misfire, so I'm thinking of the following fueling culprits:

1. Fuel Pump gauze blocked

2. Air Mass Meter

3. Fuel pressure regulator?

The inline fuel filter has been replaced.