V6 Vibration at 1800-1900rpm
 

Hi Guys,
This is not a A8 question, but I figured there are some clever chaps in here that might have come across this. I have just bought an A4 B6 (2004)
My engine (2.4 V6) has a vibration at around 1800rpm.As soon as the rev counter goes past 2000, it smooths out again. It's only at that crank speed, the rest of the time it's smooth as silk. My local garage reckoned it might be the dual-mass flywheel.
I don't think it's gearbox related, because if I rev it to 1800rpm in neutral, while stationary it still does it. (clutch in or out) I've no idea what is causing it, my local indi said it might be the dual mass flywheel, which this engine does have, but has said to replace it will cost over £1k with no garantee of a fix, which is a bit risky. He has also said it could be the crank shaft pulley which is a lot cheaper.

Anyone ever seen this? Otherwise it runs fine, car has only done 42k mpg is good for the engine, tickover a bit lumpy but not the worse I have seen.

Any suggestions very welcome.

Thanks

Wayne

Interesting........

My wifes V6 2.8 Ford Galaxy, which is basically a VW in disguise has a lumpy idle around 1800 rpm, always has. Its noticable when first started and the 'choke' is on, but after about 30 secs the revs drops and all is fine. Below problem rev range no probs and above problem rev range no probs but inbetween the whole car judders....

We got it with 29K on the clock and now it has about 45K 3 years later, its never got any worse or better.......

I'd be really interested in your conclusion on this one !!

Its pretty much the same engine as mine and it sounds a little like my 40mph stutter....which would be at about 1800 revs ish. Stutters for want of a better word but is spot on everywhere else, the vag com check shows nothing, the coil, plugs, vent pipes, leads ect ect ect ect are all sorted and it still does it. Sadly i still haven't cured it, have swapped pretty much everything so I'm just ignoring it and hoping its timing belt change will sort it, it doesn't seem to affect anything and lasts such a little amount of time. But then i don't have a manual box so it isn't a flywheel in mine! Your indy might be right?!?!

Hi Guys, yeah its an odd one, I have seen one other guy on a forum with exactly the same symtoms but he has CVT, he hasn't posted what he had done to fix it which is a shame. I think CVT has the DM flywheel.

The clutch is very high, so it could be on the way out, but I have had Audi's before with very high bite point that have gone on for 10k miles plus with no problems. Its frustrating to throw so much money at the car, on the chance that it might not fix it, especially as its more an annoyance than anything actually wrong with it.

It does need a cam belt, so maybe I'll get the crank pulley replaced while they are in there, as it won't cost much more in labour, and its not an expensive part. Once the Indi said it might be flywheel I likened the vibration to an overloaded washing machine, there is no mechanical sound at all, its just an annoying wobble, worse in gear, particulaly if you end up cruising at a speed that has the engine at the particular RPM.

Will keep you up to date.

Wayne

it definately sounds like what mine is doing....unpleasent surgey type misfire thing. Somedays worse than other. I'll list what i've swapped and that made no difference, not to say they aren't whats gone pop on yours but it'll maybe help you out.

Coil pack replaced
Ignition leads replaced
Plugs replaced
PCV pipework replaced (black trunking round engine that falls to peices)
Throttle body cleaned and reset
All vaccum pipework examined and checked (1 duff part sorted)
Vag Com scan (no faults)
Air mass meter cleaned and then disconnected (made no difference at all)
Aux air pump replaced (small black 3 armed valve from pcv to manifold)
Manifold studs checked for tightness (they sometime rattle loose)
Coolant temp sensor replaced
Many tanks of super unleaded and fuel cleaner (incase the injector was leaking due to deposits)

Nothing has changed the stutter, hiccup, hesitation,surge, gremlin call it what you like but it doesn't make any difference to the way it goes, doesn't have bad economy (well as bad as a huge car can be anyway) and frankly i can drive round it when its at its worst be increasing rpm by 200 or so.

Next on my list is timing belt as it has had one done and if they got it a tooth out it could cause an issue (though i would expect the managment system to report it) But if you find a cure please let me know.......even an expert couldn't diagnose what was wrong, just told me i'd done everything he would have and in the same order.....but being a dedicated amateur i knew that already!

Well update is, took it to a dealer who got their Audi master tech to take it for a test drive, he reckons flywheel or pulley, but only experienced the judder not the jerkiness.
It had the cambelt done yesterday, and the crank shaft pulley, by the indi, didn't change the jerking or vibration. Lambada and Airmass checked and seem ok. No errors reported by the ECU.
After driving it for a bit, he reckons it might be a misfire, apparently due to the way the coils are setup, if it had a small misfire, no codes/errors would be written. So he wants to replace the spark plugs and coils, (the spark plugs were done at 40k service last dec'09) he has explained the other option is the flywheel, everything else looks ok, the plugs and leads is the next natural thing to replace.

B@fink - I see you have already had the plugs and leads done.

I can tell this is going to be a money pit, anyone got any ideas?

Wayne

I have but plugs were done at service when i gave it a good going over and my leads were at 80 odd thou, were the next obvious weak link and looked about ready for a swap!, If the Audi master tech says its ignition then it could well be ignition! If the misfire thing has only been happening since it had its plugs done or not long after it (you say you are at 42k and they were swapped at 40k) then the plugs or leads could have a fault/damage that went unnoticed at the time of the swap? Did it do it before the dec 09 service? Hope you find your gremlin....even if its a different one to mine :D

Well latest is swapped the leads, no effect, took it to audi dealer for a 'official diagnostic' @ £100! spent 2 hours on it, and have now told me that they cannot find the fault, and want to strip the engine down and send parts off for balancing! They have pointed out that this will cost more than the £5k ish the car is worth! they admit that the engine is common is thousands of cars including the A4, A6 (and maybe the A8) and that the 2.8 is even more common and is the same engine with a few mods. so we are talking about a common setup here, yet they are clueless, I would have thought with the backup of the Audi network, they could get some help if they can't diagnose themselves?!? to say a 'prestige?' 6 year old car with 45k on the clock is a write off as far as smooth running is concerned , is a surprise.

Am I being unreasonable?

W