Misfire cylinder 2

[Mattias87]

At the moment it seems my car will not give me a break.... It is a 2002 seat leon with a AZD engine.
In the last week the check engine light has come on three times. Starts out by blinking in yellow, then the car runs unevenly and misfires. If I stop the car for a while and turn it back on the check engine light is constantly lit and it runs a bit less unevenly until it runs smooth again and the light dissapears. Then after a few days (and about 200 kilometers) it does the same thing again.
The other day when this happend I stopped the car and then when I walked out could smell a distinct burnt smell (catalytic converter?).

I have been trying to read up and seems it could be:

- Faulty coilpack (but would this not mean that it would constantly be running badly?)
- Clogged up injector
- Due to piston leaking (apparently according to some people on forums this motor will break down after 60000 km if run of unleaded 95).

I used VCDS and got a fault code for misfire on cylinder 2 along with two other fault codes. However I accidently deleted the fault codes and they have not come back on since yesterday so do not know what the other ones were.
I bought this car in april and without ever having done any DIY on a car have been able to do a couple of things on my own (including cambelt replacement, clutch master cylinder replacement and a total service). However now after reading on the internet feel I am at a loss as to what to do. Any ideas or is it time to just hand it in to a dealer?

If its simply a matter of exchanging the coil pack I guess I can do it, but how do I know this is really the problem and not due to pistons leaking? Have no way of performing a leak down test myself.

 

[Bunter6]

If you want to rule out the coil-pack, swap it with one from another cylinder and see if the error code follows the coil-pack to the new cylinder its now firing.

 

[Mattias87]

Thanks, just did this. However while idling I also tried to disconnect each coil and the idle went down and car started running rough on all four of them so at least they're all functioning to some degree.

 

[Bunter6]

Yeah they could be ok under light load and while not too hot but once up to running temp and under some load they might start malfunctioning. My B6 S4 had this problem, would be ok for about 20 mins of driving then after that one of the coils would start to misfire after about 4000rpm on full throttle.

 

[Alexis27]

Faulty coil packs can create all sorts of intermittent symptoms. Last faulty one so had meant it ran fine but would have trouble starting

 

[Mattias87]

Now when driving the car is quite hesitant now and then on all gears. And when idling its almost as if the car coughs now and again and drops a few rpms. However no new fault codes or engine light, but can feel something is not good with the car.
Is there any other way of checking the coil caps to see if that is the problem or another way of checking if its the injector or the spark plug?

All help is kindly appreciated. Read about a guy with similar problems with misfire and intermittent engine light and for him it was the piston that was gone. Am really hoping it wont be that bad for me.

 

[Alexis27]

Try disconnecting the MAF. This will force the car into a default air intake mode. If your problems clear up it's probably that.

 

[mike84]

The maf will light up the traction control light as well check the coil pack wiring for any exposed wires it could be earthing out which would explain the intimitancy of it an these ecu can take up to 200 mile to realise problems an throw them up again

 

[Mattias87]

Checked the wires and earth and seem fine. Anyone know where the MAF is on the azd engine? Could a faulty MAF cause misfiring or just the hesitation?

 

[mike84]

The maf will be directly after the air box it will have an electrical connector going to it just unplug that to test it

 

[Mattias87]

Checked the spark plugs today and the one in the second cylinder (which gave the misfired code) had an insulation that was loose and flapping up and down. Changed them all and no more coughing in idle. Still the idle is not perfecty and goes about 50 rpm up and down. However felt much better to drive so think the problem is solved. Whatever is causing the erratic idling when hot will have to be another stpry.