Fault Code 16684 and 16689 Misfires!
 

Out for a drive yesterday when Engine management and cat light came on:
Sunday, 15 February 2009, 10:59:22

VAG-COM Version: Release 409.1-S



Control Module Part Number: 4D0 907 557 N

Component and/or Version: 4.2L V8/4V MOTR AT D01

Software Coding: 04373

Work Shop Code: WSC 02324

2 Faults Found:

16684 - Random/Multiple Cylinder Misfire Detected

P0300 - 35-10 - - - Intermittent

16689 - Cylinder 5 Misfire Detected

P0305 - 35-00 - -

Misfire is very noticable.

So swapped coil pack on 5 with 6 and fault stays with 5. Swapped coil pack with 7 and fault stays with 5.

Swapped plugs between 7 and 5 and fault stays with 5.

What do we think next please? Ignition Control Unit? Broken Wire? Dont think it's injector as Cat light coming on indicates unburnt fuel!

Mike

My money would be on an ignition amplifier fault - Its quite common.....

They are on the left side of the engine bay towards the top.... There is a pair of them. You can easily swop them over and the fault will almost certainly move onto a different cylinder proving one is faulty....

For giggles, you can run the engine with one disconnected.... By 'eck 4 cylinders sounds rough :D

A cheaper alternative to LPG? :D

lol

Yes. That is my next test. If it's that I'll contact David.

Right, been out, done that and.....
the misfire has gone! :Confused:
Not jumped to the other bank, but gone. Dirty/loose contact?
Can't take it for a test drive yet as been on the pop at lunchtime. Will give it a blast tomorrow. Happy though +++

Mmm, sound like a case of beer ears (as opposed to beer goggles) to me! :ROFL:

Good result though by the sound of it - was it easy to switch over?

-oli

Yes, just unplug all 4 conectors and plug them in on the other side. :)

BTW, was up at A8Parts last Friday! You getting excited yet Oli?

Oh man, i can hardly sleep! I don't think i'll be able to stop grinning when I get in and drive off :D

-Oli

Took the car for a run on the way home from work and the fault is back but not on the other bank! Cat and Engine management lights came on when I booted it and engine ran rough. Got home and used VagCom to find exactly the same codes. Random Misfires and Cylinder 5?

Wondering what to look at next?

Cable between amplifier and cylinder 5?

How do I test? Continuity from amps to Coil Pack?

if you can, put some crocodiel clips on with the tester and wiggle the cable.

Or... if it's easy enough to do, swap it to the other side and see if the misfire goes with it.

Well had a go at tesing continuity and all seemed well. Did some wiggleing and found nothing! Now the prblem is gone. Done 150 miles and nothing going wrong. :Confused:

Ah.... Maybe you now have the 'engineer fix' like we used to have on the VCR in the early '80s (yes... I am old enough to remember them.. Just!).. They'd play up for ages.. You'd get the engineer out to look at it, and it would behave like a new unit, then as soon as he went away.. bang.. faulty again.

Maybe just some crap in the fuel that was blocking the injector for a bit and has cleared? I would go with the 'heavy right foot' clearance method.. Just boot the bugger for a bit and hope it still works :)

Boot it some more? Ok officer!

Just to close this thread, the problem went away and didn't return before I destroyed the engine.

However, while fitting the new engine at the first fire up I had the same symptoms and it was due to fuel starvation and it threw up the same code!

16684 - Random/Multiple Cylinder Misfire Detected

P0300 - 35-10 - - - Intermittent

But not the Cylinder 5 code.

So check your fuel if you get this code as well. +++