ynot5105

I have a 2000 Quattro Avant (2.8 30V) that developed a misfire on the left-bank. Sometimes it is almost insignificant, but other times it get so bad, that the motor bogs down, but doesn't die.

A brief computer analysis pointed to a faulty Lambda sensor, which for various reasons I don't consider to be the problem. The test also indicated a problem at no 4 cylinder.

Yesterday I replaced the plugs as well as all the plug leads and now it WORSE!

I want to replace the fuel filter, but again, don't consider that to be the problem either, as it is intermittent?

Any ideas of where to look? I'll be buying a VAG "tester" soon, but hasn't got free use of that facility right now.

Regards

Kris Hansen

Have you replaced the coil pack?

ynot5105

Hi Kris,

Thanks for your response; nice to hear from you, other than our previous occasional e-mail exchange.

No, I've not replaced the coil pack, but is there an easy way of testing it, before an expensive exchange?

Something else: I was going to buy the testing equipment from Ross Tec, but was extremely surprised and very glad to find that their supplier was right on my doorstep in Somerset West, South Africa!! I'll be getting some equipment from them soon, saving me expensive postage from the USA.

Keep up your excellent work,

Kind regards,

Johan Mouton

ynot5105

Kris,

I was wrong, it IS/WAS that lambda sensor on the left bank, causing a far too rich mixture on that side and the resultant misfiring!

As you suggested, I disconnected the said sensor and voila, a perfectly smooth-running engine.

I'm going to try and source one of the tools you referred to, to remove these sensors and then I'm going to try and clean them, as various forum messages direct.

I will give feedback re my experience.

Regards,

ynot5105

I've cleaned the troublesome sensors on both my A4 & A6, with no worthwhile luck.

I also bought and installed 2 different types of aftermarket sensors, first in the A6 and then in the A4. Tried various ways to reset systems, so that the cars' intelligence would pick up and recognise new electronic parts, but at best the success was marginal and temporary.

I'm therefore back at "square one". At least the A6 is not misfiring any more.

I plan to have a Unichip installed in the A6 coming Tuesday, hoping for a bit more "grunt" out of the vehicle and I'm going to have tha lambda sensors mapped right out of the equation!

Kris Hansen

It's not misfiring, that's good, yes?

ynot5105

Of course that's good, but not good enough, Kris!

There's still a problem in that the 2nd bank's (in this case) lambda sensor is not working at all, or alternatively, not working properly.

As I've said however, I hope to get them mapped right out of the equasion.