nw-indiana

Hi,

First time poster here.

I've got a couple of '99 D2 A8s (32v), and I am having a misfire issue on one of them.

The car is hard to start, difficult to keep running, and idles very low when it does finally run. It is not drivable.

VCDS gives me p0300, p0301, p0302, p0303, p0304 - cylinders 1, 2, 3, 4 are all misfiring.

I've swapped the ICMs and coilpacks for known good units from the other car with no change.

What should I consider next? Cam position sensor?

Y888

Maybe fuel pump,let someone turn on the ignition and go to the trunk and listen and see if you can hear anything weird.
Did you check spark plugs?
When was your fuel filter changed?

Had same issue month ago(pump had a short somewhere),fuel filter hasnt been changed 13 years 122k mls.
After replacing the pump iv got a misfire again and after 3 bottles of stp check engine turned off and car runs smoother.No codes so far...

nw-indiana

I'd have to dig up receipts, but I think the fuel filter is around 4 years and 50k miles old now.

I can do that as general maintenance.

The fuel pump isn't making any odd noises. I suppose I can do a fuel pressure test and compression test next.

tozoM8

I would double check the timing belt.

nw-indiana

The timing belt is pretty fresh on that one.

I had the full kit done about two years ago, probably under 15k miles. Maybe under 10k, would have to check. (Belt, water pump, tensioner, idlers, etc.)

It is possible it jumped a tooth, I suppose, but that shouldn't be the case. I'll take a look.

robertjholt

Hi There,
I'm well versed in the 97 D2 4.2 32v. First check for a spark on all cylinders. Pull the coil packs on the one bank which isn't firing and plug in a set of plugs, run the car very briefly with someone checking to see if there is a spark. If there is a spark, it could be one of the following:

One very easy check is the two rubber hoses at the back of the block, under the intake manifold. there is one that goes into the intake and the other goes into the other bank valve cover. Both degrade over time and split where you cant see them causing a lean misfire on multiple cylinders. not usually on only one bank of cylinders though, but definately worth checking out. they are located here:

audipages Engine Breather Hose Replacement

item #3 in the picture actually goes into the intake and is reversed. This image is for the old Audi V8 engine which is slightly different.

These hoses are expensive, but worth the money as they have various bends and direct fit is best:

Amazon.com: audi a8 97 breather hose

Let me know what your compression test results are.

Sometimes you can force the car into closed loop by unplugging the Mass air flow sensor in the airbox. This can rule out a failing MAF if the car runs OK after doing this - try it. MAFs are not too pricey and can be had for around 120$.

It is also rare for the wiring to be bad feeding the coil packs on one bank. Check the voltage going to each connector.

How are you scanning for codes? If you are using VCDS with an ebay CAN connector, then you can license it for 99$ and get individual misfires occurring in real time. If you do this test, you can place the engine under load (how to truly test a coil stationary), by placing the car in reverse with the ebrake on and left foot on the brake hard. Then raise the rpms to around 1500 and see how smooth the engine is.

I have the bentley CD for this car, let me know if you need any pages/specs for testing. Happy to help out a fellow A8er!

nw-indiana

Thanks, robetjholt.

Have you found reasonable price for the Bentley CD? I'd like to have one, but it was over $1k when I asked about it, iirc.

I have licensed VCDS from RossTech, so I can watch the code count increase in real time.

The front and rear driver's side breather hoses were done when the timing belt was. I don't think we did a second rear hose, so it is undoubtedly due.

I am starting to toy with the idea of pulling the motor out and replacing everything on it that is known to fail so I can rely on the car again. For the past year and a half, it hasn't been driven much at all because it hasn't been reliable.

Would you be willing to help me assemble a list of everything to do on that motor so I don't have to worry about it for a few years?

I am thinking -

ac compressor
alternator
power steering pump + hoses
water pump
timing belt + tensioner, idlers, etc.
breather hoses
valve cover gaskets
cam position sensor
thermostat

Are there other common failures I should plan for?

nw-indiana

Also -

oil cooler (replace plastic pipe with aluminum)
oil pump
clean out oil pan / de-sludge
oxygen sensors

rebuild / bulletproof transmission

The idea is to take a high mileage car and get it ready for the next 50k miles.

the_duke

Audi A8 1997, 1998, 1999, 2001, 2002, 2003, S8 2001, 2002, 2003 Repair Manual on DVD-ROM - Bentley Publishers - Repair Manuals and Automotive Books

robertjholt

http://m.ebay.com/itm/310550813248?fits=Make%3AAudi%7CModel%3AA8
Make an offer on this and it will save you a few dollars. The version I got meant I had to run Windows xp on a vm to use an early version of Internet explorer. It was still a bit cheaper though overall.

The Bentley manual is well worth it - I changed out the upper oil pan gasket and rod shells without taking the engine out and crucially need led the hearing color code location and crank dimensions. All that stuff is in there.

They do go the distance...

With regards to what to do, you can do a heck of a lot of stuff with the engine still in the frame. I would only fix what is needed though. Good preventative maintenance is the key. Transmission fluid change is paramount with oem liquid and filler. Also make sure you change it the right way - there is a procedure you must follow. Engine oil - I run pentosin 5w-40 and it's really good.

The oil cooler plastic pipe replacement procedure can be done by lifting the engine on one side to get it to clear. It's not worth don unless you are loosing coolant though.

The fan clutch bearing can wear out and it's 120$ and you need a press to replace it. It can be done though. Idlers are cheap and the belt is cake to replace.

Timing belts are tricky to do but you can rent the correct cam holders and crank pulley holder from blauparts for a hefty deposit, but overall if you buy their timing belt kit, it's only like 75$

Got to a point with my wife's a8 that all I do is change brakes and fluids now. She got it at 197k and it's done 211000 now in one year. Not freeway, windy mountain roads.

The bores in these engines are Alisil which is akin to a glass finish. When I was swapping the rod shells I took a good look at the bores. I couldn't believe how mint they were. The furthest rod bearing had the most wear, but it still wasn't knocking. When I plastigaged the rod journals prior to installing the new shells, each clearance was the same and on the low end of the tolerance scale. Blew my mind...car this old with no wear on the crank.