Missfires ??

[dr.sah]

I have missfires on my RS4 B5 2001, the main problem is 5th cylinder, the rest are not a problem. I see those missfires if I leave car running, and if i drive they are gone.
Does anybody have the same situation?

[Contigo]

Is that what VAGCOM is saying? Could be boost leak or suchlike.

[Virdee Autos]

Are you looking at the misfire counter on measured block values? If so, then mine breads a few when left to idle, and resets back to zero, and so on. Nothing to worry about unless your engine light comes on due to this

[dr.sah]

Yes, it is like you said. But sometimes I got yellow light, for day or two, and than turn it off by her self. Last time I got the light when i have driven downhill for 3-4 kliometres. Also sometmes tha car is a little nervous at 800rpm.

I know that couldn't be something big, but I want to fix that, if i could.

[Contigo]

These cars are pretty lumpy on tickover/idle and the revs do seem to jump a bit.

[DutchRS4]

Yeah, mine acts the same. Don't worry. It's the character of the beast
It just hates to stand still and screams of joy when feeding boost.

[grizz]

What's your fuel trim like ?? Take a look at block 032 , It's short & long term fuel trim .

[Virdee Autos]

Maybe check that the spark plugs are fully tight. There have been known issues of some becoming loose!

[dr.sah]

i think they are Ok, because we put them out, to check it. In this days I will get new one.

[wozza]

I've managed to clear up quite a few misfire issues - checking the usual out on these first i.e - duff coil packs, duff amps, vac and boost leaks, spark plug tightness, maf knacked.

I then went onto contact cleaning all the ignition amps and the maf contacts and also using high tension silicone grease to prevent arcing along the spark plug boot. Which substantially helped out - I still get the odd hiccup but nothing like before. Considering that the contact cleaner and grease is a couple of quid - its worth a shot before purchasing expensive items..

One other trick (I saw whilst at MRC) was to tweak the "Torque on Idle" setting - altering the timing slightly on idle. Also helps with the stammer that can happen when pulling away in first gear.

Obviously - checking for duff amps can be done just by swapping em over and seeing if the prob moves if it's one bank that plays up

[jojostar]

In my case it was a small crack in the cylinderhead (within normal tolarences) which caused missfires.

[TopBear]

In my case it was a small crack in the cylinderhead (within normal tolarences) which caused missfires.

Interesting, how did you find that out?

Where are the tolerances specified.

[jojostar]

The "crack" if you can call it that was caused by a mapping session the did not turn out to be as good as it should be. After the session the engine running on idle was very very bad noticing the misfires out of the exhaust. At the moment the right side cylinderhead has been replaced and instantly (the right exhaust pipe did not show any misfires ) i have a custom spilt exhaust. As far as i've read tolarences are a couple of milimters (according to Audi). I think there are a couple of example pictures here on the site.

[chancha]

The "crack" if you can call it that was caused by a mapping session the did not turn out to be as good as it should be. After the session the engine running on idle was very very bad noticing the misfires out of the exhaust. At the moment the right side cylinderhead has been replaced and instantly (the right exhaust pipe did not show any misfires ) i have a custom spilt exhaust. As far as i've read tolarences are a couple of milimters (according to Audi). I think there are a couple of example pictures here on the site.

When you mention misfiring on idle, was it misfiring or popping? I've noticed this on mine on the over-run.

[Doug_S2]

just use a wideband and see the mixture on idle to see if it ia mixture problem. then see if the car is running strange timing or differing loads on idle.

check cams