A8 2.8 Sport Possible transmission / misfire problem

[dboy998]

Hi Guys, I bought an Audi A8 2.8 Sport a few weeks back for under a grand, I knew it had a couple of minor niggles but its a temp car so wasnt too fussed. Reading the forums have already helped me solve the stalling when coming to a halt issue, (Turned out to be the cracked breather pipe problem, someone had tried to tape it up... amateurs)

So not being super technical i thought i would have a read on here to see what i could find, whilst there seems to be similar problems occurring i couldn't pinpoint the cause of mine.

So she Starts immediately and runs perfectly when engine is cold / warming up. irregard of gear either left in Drive or moved to semi auto and selecting gear of choice, no misfiring, no shuddering, gear changes are smooth acceleration is smooth. No rough idle everything seems fine.

Once engine starts getting up to temperature, say 15 - 20 mins driving the following starts to happen.

whatever speed i am sitting at, 30-40mph, 60-80mph if i apply some light pressure on the accelerator the car starts to shake, shudder almost feeling like a misfire but the second i slip the gearbox into neutral this stops, put back into gear and it shudders a little bit but maintains speed. if i apply a heavy right boot to the accelerator then there's some more violent shuddering and then i calms down again.

I've ruled out plugs and coil packs and it doesn't happen all the time and in neutral the engine revs perfectly well. in my mind it is pointing towards a transmission related problem, so first thing I think I am going to do is replace the gearbox oil. (and hope large chunks of metal dont fall out)

This is happening on an Audi A8 2.8 Sport 1997 D2 Model which i bought about 3 weeks ago for under a grand. Its got 128,000 miles on the clock and a full service history (well there is a gap between 110,000 and when i bought it, so i threw it straight in for a full interval 2 service. This shuddering was not happening before the service at all, but I cant imagine what being changed in a service could cause such such a problem. I have detailed the advisories that came out of that service in case it helps.

1. Rear Brake Discs pitted and pads are separating

2. O/S rear brake Caliper (handbrake poor)

3. Exhaust corroded but not holed

4. Creak from front steering / Suspension possible bush fault

5. Auxiliary drive belt cracking slightly

I'd be very grateful for any pointers that you guys might think, or if there is more information you need i will try and help.

[cruiser647]

I wouldn't rule out the coilpacks and plugs. Swap the packs around and see if anything changes.

You also have the 'amp' that powers the coilpacks/plugs. I would also change the MAF. That affects how the gearbox behaves, and is normally only £60 for a proper Bosch exchange. DO NOT USE ANYTHING OTHER THAN BOSCH!!!

A gearbox fluid change would also help.

Hope that helps.

[dboy998]

Thanks Cruiser for such a prompt reply.

Ill have a hunt round for capacity of gearbox and get some gearbox fluid sorted this weekend, where have you seen a bosch MAF for £60 i ct seem to find a new one for less than a ton. but my googlefu is weak with car stuff..... ill read up on how to swap the coil packs over, try that and post any results.

[PsYcHe]

Where are you located, might be someone nearby with Vag-Com that could scan for error codes for you, maybe pinpoint it.

[dboy998]

I am in Fife,Scotland.... Just over the bridge from Edinburgh.... I have also put a post in the VAG-COM forum asking for help. I am assuming the database isnt working as i coulnt get on to it.

[cruiser647]

Try Murray's in Hatfield for a bosch MAF.

Although to be fair, I am not certain on the price.

Forgot to add, the Audi gearbox fluid isn't cheap, and there is procedure you need to follow. It's on here somewhere in the A8 section......

Edited May 16, 2012 by cruiser647

[PsYcHe]

Not sure about someone in Fife, but if you're likely to be through the West coast in the near future, I could scan it for you. No plans to be over that way for a couple of weeks.

audipages.com has the gearbox fluid swap, though not sure if the 2.8 has a different gearbox, procedure should be the same though.

[dboy998]

Thanks for the pointer Cruiser.

right quick update.

I pulled the maf and gave it a good clean with electrical contact cleaner, there was some clear brown (if that makes sense) gurp over parts of the two wires, one with the sensor was a little worse, but not sure if that was gurp or broken up protective layer.. either way its all clean to the wire now haha (rightly or wrongly)

That hasnt made any real difference.

I have noticed that if i stay in manual mode with the gears (i.e gear selector to the right and use up/down sequential selection) then the stuttering effect is reduced greatly. I have also noticed that it appears to be more violent / common when the rev range is between 1000 and 2000 rpm. Essentially if i keep the revs above 2k then the symptoms are almost undetectable.

FYI A friend has an Autel Maxiscan MS300 CAN OBDII scan tool. I borrowed this and connected up to the socket underneath the ashtray, it returned no DTC codes at all, and the IM readiness menu could only read CCM - Comprehensive Components Monitor, this returned all ok and confirmed MIL light off.

I am going to assume that a proper VAG-COM or even a "fake" cable and the software will be able to interrogate in more detail ?

not dropped fluid or spent any money on it yet, i really want to try and diagnose the problem before throwing any money at it. I know that sounds cheap but ive got a wedding in a couple of months !!

Psyche - I cant remember the last time i was over the west coast at all... It sounds as if you come over to the dark side, sorry east side on occasion, are you over any time soon? I would love to take you up on your offer if it still stands sir. (of course i would need to know your preference in beer first)

Thanks for the ongoing support guys.

[cruiser647]

The other thing you can try is to change the coilpacks around.

See (or hear) if it sounds different.

Did you change the plugs?

[dboy998]

Update time..

So as I have mentioned I really didnt want to start trying anything until i had been able to get some kind of diagnostic done on it. So i spoke with ross tech and got some "free advice", went and bought a KKl / VAGCOM 409.1 compliant USB cable, downloaded a free copy of VCDS Lite 1.1 and off i went.

Ran through the available module and components and on the engine component i got the follow error code.

VCDS-Lite version: Release 1.1

Control Module Part Number: 4D0 907 551 M

Component and/or module version: 2.8L V6/5V MOTR AT D02

Software Coding: 04153

Work Shop Code: WSC 00613

VCID: 301393C3E32D

1 Fault Found:

17924 - Intake Manifold Valve (N156): Open Circuit

P1516 - 35 - 10 - -- Intermittent

So grabbed the code and dumped it up here where all the Audi geeks hang out and gracefully request any kind of translation. Does this look like it could be the cause of my problem?

Thanks again guys for helping in my quest for knowledge (and helping me understand how to fix my own motor of course)

As a side point, theres a function in the VCDS Lite software which allows you to check for OBDII compatibility, hitting that buttone it runs a test, mine came as successfull and it said OBDII software should work..... and thats on a 1997 A8 which shouldnt theoretically be OBDII compliant at all according to the nice man at Rosstech anyhoo.