Rough Running On Cylinder 3.......

hoarec said:

OK.....I would appreciate your views and comments on this problem.

My car has been running a little 'rough' for a while now on both LPG & Unleaded. I took it to a garage who put it on their test book and said that it was a 'misfire on cylinder 3'. When I questioned him on this , he said that it could be:-

1) Faulty Spark Plug
2) Faulty HT Lead
3) Faulty Coil
4) Faulty Fuel Injector
5) Sticky Valve.

Anyway....I now have a Faultmate Extreme and have started to diagnose this myself.....I replaced the spark plugs last night and run the diagnostics and it states that it is 'running rough on cylinder 3'. The values on the other cylinders are either 0 or 0.1 where as cylinder 3 is between 4 & 7.... What does this mean?

The HT leads were replaced early last year with Magnecore so although it is unlikley to be these ( I will swap the leads around tonight to see if the problem moves) I will check anyway.

The coil packs were replaced at the same time, however is it likely that only 1 cylinder would be affected, and how could I check this....

If it was a Fuel Injector, surely this would not affcet the running on LPG and visa versa, unless both types of fuel injectors are faulty on cylinder 3.....

I have recently been using red-ex in the petrol and had a flash lube kit fitted to the LPG while I had it serviced to help with injectors and valves......



Does anyone have any ideas or comments that would point me in the right direction....?? I have not had a proper play with the faultmate as yet, so is there any functionality on there that may be able to help me further....

Click to expand...

Wookie said:

What colour was the plug on No3 compared to the rest, did it stink of fuel or oil?
Check for a crack etc in the dizzy cap around No3, change cap if possible.
Buy a set of spark testers and fit them to the side with No3. You should be able to see if any spark is weaker than the others.
Run a compression test on the same bank, if low readings add a squirt of engine oil and repeat. If no or little change then it points to top end.
If you have an air line, pressurise No3 when on compression stroke, listen for a hissing sound in the exhaust or air intake.

Click to expand...

hoarec said:

OK.....I would appreciate your views and comments on this problem.

My car has been running a little 'rough' for a while now on both LPG & Unleaded. I took it to a garage who put it on their test book and said that it was a 'misfire on cylinder 3'. When I questioned him on this , he said that it could be:-

1) Faulty Spark Plug
2) Faulty HT Lead
3) Faulty Coil
4) Faulty Fuel Injector
5) Sticky Valve.

Anyway....I now have a Faultmate Extreme and have started to diagnose this myself.....I replaced the spark plugs last night and run the diagnostics and it states that it is 'running rough on cylinder 3'. The values on the other cylinders are either 0 or 0.1 where as cylinder 3 is between 4 & 7.... What does this mean?

The HT leads were replaced early last year with Magnecore so although it is unlikley to be these ( I will swap the leads around tonight to see if the problem moves) I will check anyway.

The coil packs were replaced at the same time, however is it likely that only 1 cylinder would be affected, and how could I check this....

If it was a Fuel Injector, surely this would not affcet the running on LPG and visa versa, unless both types of fuel injectors are faulty on cylinder 3.....

I have recently been using red-ex in the petrol and had a flash lube kit fitted to the LPG while I had it serviced to help with injectors and valves......



Does anyone have any ideas or comments that would point me in the right direction....?? I have not had a proper play with the faultmate as yet, so is there any functionality on there that may be able to help me further....

Click to expand...