Diagnosing a failure that resulted in a trip on the flatbed

[jbarhydt]

I have a 1999 US spec C2 Coupe with a Tiptronic. I bought the car 2 years ago with 60k miles on it, and recently turned 103k miles. I've had to fix the various oddities of this model, but as of yet i have no oil leaks and the car has run great until today.

While crusing on the interstate I felt a "thud" from the rear of the car, and the engine lost power. I was able to coast down an exit ramp and onto a side road where the AAA flatbed would soon pick me up. When I turned the key I could hear the starter motor running (fast) but there was no apparent engagement with the flywheel. There are no fluids dripping onto the ground that i've seen with other massive failures. When I get home from work i'll hookup the Durametric and see if there are any interesting codes, but for now i'm trying to determine what the next steps should be.

So here are a couple of other pieces of information. About a week ago as i was leaving for work in the morning i heard a "whirling" or "spinning" sound coming from the back -- moderately slow in frequency, and only when the car was deaccelerating. The sound was almost like a fan blade hitting a plastic shroud every rotation - but with a bit more of a differential-whine to it. When the car was up to operating temperature the noise would go away. Others on the forum have described this noise with the suggestion that it is a wheel bearing - but i was able to convince myself that it wasn't a wheel bearing by putting the tran in neutral while the car was rolling. The noise was controllable by engine speed - not by road speed, which seemed to point more towards engine/tran than wheel bearling. I drove the car for the next 3 days and noticed that the noise was about the same - and always went away when the engine was up to operating temp..

I hooked up my Durametric and found no error codes. I reset the adaptations to see what effect that would have on the Tip. The next morning the car started rough but within 30 seconds was purring smooth. I assumed that the adaptation reset was the cause of this. Best yet -- the whirling noise was no longer happening. As a side note - my fuel mileage improved by 1 mph after the adaptation reset - but that could be just dumb luck.

So back to this morning -- "thud" on the highway, and a tow-truck.

I haven't started digging into my shop manuals yet -- but i'm assuming that i've had a failure in the Tip - maybe the torque converter? The older German cars that i have have been manual gear boxes -- a clutch failure wouldn't necessarily prevent me from starting the engine - but i'm not familiar with the automatics.

This sound familiar to anyone?

Thanks in advance -- this forum rocks, and the last 40k miles on this car have been a blast - in part because of all of the good information this forum offers.

[jbarhydt]

Pulled the fault codes using my Durametric

Tiptronic code 22 - Unknown fault code

DME:

P1531 Camshaft adjustment bank 1

P0341 Camshaft sensor bank 1 Short to B+

P1397 Camshaft sensor bank 2 short to ground

P1539 Camshaft adjustment bank 2

P0102 Mass air flow sensor short circuit/open circuit

[Loren]

DTC 22 = P1770 Load signal from ECM Substitute Motronic value, fixed shift map (KFO)

Possible cause:

- Wiring

- Tiptronic control module to B+ (Open circuit/short circuit to ground, short circuit)

- ECM

Since you have several faults with open/or shorted circuits I would start with a detailed inspection of the wiring in and around the engine and transmission.

[logray]

Certainly an interesting set of codes. The starter spinning freely could be a caues for concern, hopefully it is just the bendix.

[wvicary]

Hopefully you don't have a mechanical fault in the engine. I would try turning the engine over by hand to see how it feels or makes any odd sounds. Always turn the engine in it's normal direction of rotation.

DTC 22 can also be caused by a lost signal from the MAF sensor.

[jbarhydt]

Thanks for the pointers -- i'm getting the feeling that i might be dealing with multiple issues. I put the car on the lift and started inspecting the wiring - visual check and disconnect/reconnect everything i can reach. I pulled the starter out to inspect the starter and inspect the flywheel. Bench test of the starter makes me wonder about a weak bendix - after a second of spinning is trys to retract, so i'm leaning towards a weak bendix but haven't given up on a possible wiring issue. I was able to rotate the motor without any odd feelings or sounds -- since the plugs were still in the compression was working against me - my sense now is that this is unlikely a mechanical fault. As i rotated the motor i did a visual on the flywheel for a full revolution - no visual indications of an issue. Next up is crawling in the back seat and inspecting the wiring on top and trying to eliminate everything i can before dealing with the control modules. I'll search the forum but is there an easy way to bench test the MAF with a VOM (while i have it out of the car)?

[jbarhydt]

As it turns out the problem does appear to be a mechanical fault. After finding no wiring issues, i went back to the basics and started with looking at the oil. I had checked the dipstick but it was clear. However, the filter seems to be clogged with bits of bearing shavings.

Last question that i have before i start investigating replacement engines -- knowing that the engine shot craps, is the Tip fault code noise, or is it possible that the Tip and the engine both failed (maybe one contributing to the other?)

Thanks for the help and great ideas!

[fpb111]

Pull the filter element out, let it drain into a clean bucket, cut the ends off spread it out and take some pics. Look in the "clean" bucket to see what landed in the bottom. Take some pics, post the pics.

Edited June 11, 2012 by fpb111

[fpb111]

Possible engine from Rennlist

if anyone needs a 1999 996 engine/transmission

just saw this listing on the portland oregon CL for a body damaged 996 w/what i assume would be a good engine/tranny for $9000 - no affiliation:

http://portland.craigslist.org/mlt/cto/3060128530.html

[jbarhydt]

Pictures as requested. Pulled oil sump cover- lots of shiny bits, and a picture of the oil filter.

[rb101]

This is not going to turn out good....

[Prhartley]

Based on the codes and that amount of metal, I would suspect the ims bearing has disintegrated.