RS246.com Forum :: The World's #1 Audi R, S and RS Enthusiast Community

Hi all

I've noticed my idle sometimes makes the exhaust wobble and you can see the engine ever so slightly shaking so I Vag-com'ed it and it did'nt come up with any fault codes.

Did a misfire recognition log (measuring blocks 014, 015 and 016) and a run at idle for 10 minutes only produced 2-3 misfires on two cylinders (which I think is normal). Could it be new engine mounts needed ?

cheers

Al

Mines is similar, a bit choppy sometimes..

Its well documented by a few owners on here that they arent all 100% smooth at idle.

The ECU only registers a 'misfire' DTC code if more than 100 misfires are registered every 60 seconds.

Have similar issue(s)

1) Slight, annoying, cant diagnose poxing misfires

Gone through the car and done (checked/sorted) all the standard stuff to sort i.e maf, lambdas, plugs, plug boots, vacuum leak check, charge pressure leak checks, coil packs, amplifier tests + 1 replaced, throttle body adapt, fuel trim reset, battery check, battery terminal cleaning etc etc..

Each item showed some improvement - final thing I've done is get some silicone grease on the bottom of the plug boots a) to spark insulate them b) to let them slip over the plug and allow the electrodes to make contact.. as I noticed on a new coil pack for a seat that it had a dab of silicone grease on it as standard.

Seems a lot better now - still occasional wobble but nothing like before.

http://www.maplin.co.uk/Module.aspx?Tab ... 6&doy=22m4

(Look for RE90X - as it comes also as a tube of gunk)

2) wobbly exhaust - found that the last but one exhaust mount has a broken weld - common fault I'm told.

Some good points there. Mine also does it ever so slightly, nothing major, but enough to annoy me! Can be ok sometimes, and other times worse!

How did you check the ignition amplifiers...resistance?

Also the grease on the tips of the plug end caps is a good idea, something that I will do shortly when I change the plugs.

The amp output was plotted on a picoscope setup (http://www.picotech.com/) and it was pretty evident from the trace that the amp was duff - think there's some example traces on the site. In the end just compared the two and a new one on the plot. Did suggest to my mechanic that the simplest way was to swap em over and see if the problem moved, but the coils were'nt tha flash so difficult to spot it this way - compound problem.

One other thing I my well do is to check for corrosion on the ignition relays - read somewhere that this can cause variable voltages to the ECU etc. Either replace or open em up and squirt PCB cleaner on them to remove any oxide. Could be a bit above and beyond the call of duty tho and am poss getting into obsessive compulsive disorder territory!

Mine was perfect until i changed the spark plugs when i serviced it, i am going to refit the old plugs to compare.

mine had i slight what i would call a shudder now and again but Golichs one and got it checked by Audi that said the couldn't find a problem so maybe just one of those Audi querks you have to live with like the stiff gearbox when cold

wozza wrote:Could be a bit above and beyond the call of duty tho and am poss getting into obsessive compulsive disorder territory!

No your fine mate, though if you start doing 'all of the above' everytime you fuel up, then your in trouble

I remember reading on here that sometimes the spark plugs can become loose, and create a lumpy/misfire idle.