Misfire

[devans]

Hi,
Got in the car this morning and after 5 minutes the engine management light came on. Whilst I was only driving a measly 15 mph I did feel that the car may have been a little jerky. Kept in second gear as only 2 minutes from work.
I've recently had a new clutch fitted, not sure if this is relevent!
Whilst my last service was over 12 months ago, it did have a service at 98k which included plugs, oil, filters etc. it has only covered 7k since its last service.
Does anyone live near cannock, West Midlands and own a diagnostic tester who could show me how this works to see if I need to invest in one and would anyone think that the problem may well be a plug or coil. It seems to tick over ok at the moment but have only just noticed this issue.
Am only asking if someone is local as otherwise I will need to drive 20 miles to my nearest indie and don't fancy that with this light on.
Ps, variocam solenoid changed 2 years ago,
Thanks
Pps. If nobody is close will a normal garage closer still be able to detect faults using they're diagnostic tools non indie etc

 

[devans]

Just had AA around and found that there is a misfire on cylinder 3 and cylinder 5. Codes P0303 and P0305.
The chap did say to me that it is unusual for a fault to occur on two cylinders but not impossible.
As I stated earlier, the clutch was recently renewed so it might be that the leads have perhaps come loose on the coils.
However, what is the best way to attack this? Would I be right in assuming coils, then plugs as a starter for 10?
If so, does anyone have a drawing which shows me which cylinder is which. Hopefully 3 and 5 will be on the same side and hopefully have coils and plugs at the easy end.
I have watched a video on you tube and it looks a pig of a job. Any help with a layout drawing/picture would be really appreciated.
Thanks

 

[Richard_Hamilton]

Coil packs would be the first port of call for me. Unlikely that the plugs have gone.

If I was at my PC I would post a nice diagram, but working on my iPad you will have to do with this:

Front

3 6
2 5
1 4

Rear

 

[thirteeneast]

I would put more trust in what Greg's the Bakers could diagnose about a Vehicle than I would the AA.
I guess that he didn't fancy laying down on the floor to test one of the coils either.
And as Richards diagram, He would have needed to know the firing order.

 

[devans]

Many thanks Richard,this helps tremendously.
On another front for thirteen east I did appreciate the AA guys diagnosis but am interested now in how you test the coil. What will I need and how do you go about this. I am interested in doing the job myself this weekend
Many thanks

 

[thirteeneast]

Well, he should have tested them and I wouldn't recommend for you to play with those sort of voltages. but if you cant physically see that the coil is breaking up from the heat from your exhaust you could check resistance across the coil but I think this would only help if its got a complete short.

Bearing in mind how common coil pack failure is and you got misfire on two banks I think its a done deal.
My opinion of the AA is they used to employ mechanics not people that just plug in diagnostics kit.

How old are your coils?.

 

[Richard_Hamilton]

Because the fault codes are on two particular cylinders, I think you can be reasonably confident it is the coul packs. It would be a different matter if there were codes on all cylinders on one bank, for example.

As Richard says, the insulation deteriorates on the coil pack, and you will probably find that it is flaking off when you get to them. If the plugs were changed not too long ago, I think it incredibly unlikely that two would have failed.

I think that in this case the AA did you well. Just getting those fault codes has given the chance to diagnose the problem. What he didn't know was that it is a common problem, so he wasn't much use in that respect....

Here are some instructions:

 

[Richard_Hamilton]

And here is that nice diagram I mentioned last night:

 

[devans]

Thanks again to you both. I always thought that the ignition coil and plugs was an extremely difficult DIY. Couldn't believe it when I tried is myself. Job done in no time at all. Mind you, numbers 3 and 5 were probably the easier ones to get access to. Number 5 was cracked in a number of places whereas number 3 looked fairly new. Anyway, both replaced, car running fine and engine light has now switched off so 'Happy Days'.
Thanks again.

 

[thirteeneast]

I'm Pleased Good job,

Did you replace just two or all?

 

[devans]

Just the two coils as if I need to do anymore the job is simple enough. Got them for a total of £56 incl vat. If buying from eurocarparts, type in PARTS25 and you will get 25% off.

 

[thirteeneast]

Did you get the Bosch packs?
I have always stuck with them, I heard some poor feedback on Coil packs other than the Bosch.
Maybe someone else may know different?
But I was to the understanding to stick to the OEM Bosch coil pack.

 

[Richard_Hamilton]

Beru also supply them to Porsche, and I think they are equally good.

 

[thirteeneast]

Yeah, Used plenty of Beru products in the past on Beamers etc and not had any problems and would personally rate Beru eqaul to Bosch anyway.
But I've seen plenty of unbranded Coil packs and the quality compared to OEM did not seem good.

E,g: top of pack just filled with potting compound, Poor life expectancy and poor firing.

 

[devans]

They sell Bosch, Beru and Unbranded. There was no real price difference in the Bosch and Beru so I bought the Beru coils to match the others already fitted.
I wouldn't touch the unbranded particularly as it is electrical parts which as you will be aware can at times be the most difficult things to diagnose if things go wrong.

 

[thirteeneast]

Good job,

I was afraid for a minute you might have gone for the unbranded (There absolutely nasty).

My brother bought some once for a VW Golf, they lasted about two months and ran like crap.