CEL...misfire.

[>RS4<]

Need some help here guys.

For two weeks my RS4 has a CEL coming up,we've had a vag-com connected to it and it detects a misfire on cylinder no:4

I have changed the spark plug and fitted a new coilpack but the problem is still there.

I can hear the engine not running normal (very slight judder) when it's stationairy but when i drive with over 2000 RPM's it appears to run normal.

Are there any other part that I can check ? Maybe injector??(don't think an injector can cause a misfire but i don't know)

I really don't want the stealers to dig into this,keeping my car for XX weeks...and presenting me the bill for not knowing what they've done...

Thanks

[SimonC]

Could it be this? http://www.rs246.com/index.php?name=PNp ... t=cam+wear

What was the spark plug like? Did you compare it to the others?

Are you sure you identified cylinder 4 correctly (no offence intended)? Remove all six plugs for comparison. Have you considered a compression test?

[>RS4<]

Hello Simon, no offence taken offcourse.

Spark plug was normal (light brown colour)

Yes i'm sure it is cylinder no:4 as the vag com detected it as misfire on cyilinder no:4 which is if you're standing in front of the car right cylinderbank first one on the fenderside.

I'm not keen on repairing the camshaft thingy TBH.....

How can I be sure what it is?

[Nige_RS4]

It might be an EGT probe on it's way out too. Does it only happen at WOT or all the time?

[Virdee Autos]

Yep do a compression test first of all 6 cylinders, then take it from there.

[R5YUG]

If you've changed plugs and coil (try swapping one of the other coils to see if the problem follows the lead) - Not sure of the exact firing order but it should be firing in banks of two. Failing the all important compression test, a remote possibillity could be a blocked injector.
I've had a similar problem on a VR6 - at idle there wasn't enough pressure in the rail to get fuel into the dodgy nozzle / injector - worth a sniff anyway - but simplier to check the compression before fuel rail and injectors

[>RS4<]

Hmm i just had some new bigger injectors fitted for my new set-up..

Maybe this is causing the misfire??

[Virdee Autos]

yep you could check that first!

[R5YUG]

simple as = no or limited fuel = no fire / - You would see sooted plug - try some red-ex in your mixture

[>RS4<]

Will do guys! I'll keep you posted.


Any more info welcome!

[>RS4<]

It might be an EGT probe on it's way out too. Does it only happen at WOT or all the time?

Sorry Nige,didn't see your post,the cel is on all the time.

But it came on after doing 300+ km/h on the autobahn tho....

[>RS4<]

Yep it's there......car has been to the stealers for a compression test and all cilinders are good exept no:4....

Stealers think there a crack in the cilinderhead,me too tbh.

And this when i've always been SO extremely carefull with it.

FU*K!!!

[Nige_RS4]

a) Is the car under warranty and b) do you trust your dealer? If the answer is no (or thereabouts), I would take it to a specialist for a second opinion and wouldn't let them change my airfilter, never mind take my engine to bits.

Just my 2p worth.

[rocketmq1]

RS4
What ever came of this? as it sounds very familiar to me at the moment!

[A20LEE]

a) Is the car under warranty and b) do you trust your dealer? If the answer is no (or thereabouts), I would take it to a specialist for a second opinion and wouldn't let them change my airfilter, never mind take my engine to bits.

Just my 2p worth.

Specialist, dealers don't know what there doing.