BDubya

What differences exist between the ATC engine and the AWP, and how might they affect me in a swap?

I have a 2000 TT which the PO screwed up & the original ATC engine was replaced with an AWP. The shop that worked on it--VAG virgins, every one of them--gave up and I ended up with the car at what I think (thought??) is a good price. Although it ran when I got it, the dash looked like a Christmas tree with all the lights lit up. After clamping down at least 9 separate hoses that were either not connected or not clamped, I've got it running OK at 2000+, but turning codes below that. This sounds like a vacuum, or maybe boost leak, but acts suspiciously like a MAF failure, too. I've ordered a Bentley CD, and have the VAG-COM codes, but then came across the fact that the wrong motor is in the engine bay!!

So, at this point, I am trying to find out a couple of different things:

1) I know that the shop called in the VIN to Audi to get the list of what they needed and were told 'AWP' . . . since the build tag says 'ATC', and it's a 2000 model, why would they (Audi) have told the shop the wrong one??

2) Since the AWP is a variable cam timing motor, and my car will not have the wiring nor the ECU expectation of the cam signal, what problems might crop up if I keep the AWP motor in it?

3) Other than the cam timing issue, what other differences are there in the motors, and what effect would they have on using it?

Thanks
Brian

OldSchool AG

i would suspect most of the differences to be external to the motor... the rods, pistons, valves, crank, etc should be the same. not sure how the variable cam timing is implemented on the AWP as i have an ATC.

GorTT

Seems like the next step would be to find an ECU for AWP.

RoberTT-WWCD

so the ECUs are different along with the varible cam sensors and such.

joe@vwvortex

if I remember correctly - the ATC has the older forged pistons as well.

OldSchool AG

this would not be an easy swap under any circumstances, unless maybe he had an entire wrecked AWP TT to scavenge. Still... not fun, to do properly, IMO.

RoberTT-WWCD

True Joe as well as push in instead of bolt on coil packs.

BDubya

I really appreciate the conversation, guys. Here are my thoughts this morning about a couple of the subjects. Please correct my thinking if I'm wrong on this stuff.

About the variable cam timing: Is there a "default" setting for the cam timing? If not, would it just remain at the same setting as when the motor was last used? Since the ATC car has no wiring or controls related to this feature, there is no future way to provide the codes needed to control it. As it is now, the engine runs just fine from 2k-5.5k. Below that it acts like there is a vacuum leak and above that there are sporadic misfires.

About the ECU: Changing the ECU doesn't make sense to me--if I did that, then the wiring harness and maybe all or some of the sensors would need to change, too. It would be far easier (and probably more successful) to simply go back to the old ATC block and start the process over.

About the block/turbo/pistons/etc: Nearly all instructions in Bentleys include both the ATC and AWP motors in the same writeups. That the internals (pistons, rods, etc) are different shouldn't matter unless there is an external (wiring, hose, etc) difference as well. The same can be said for the turbo and other bolt-ons . . . if parts attach correctly they should be OK I think: The ATC ECU is expecting the signal from the ATC turbo and nothing there was changed . . . that it's bolted to an AWP block shouldn't make a difference. The problem would be if the plumbing of the AWP block is different from the ATC, which doesn't seem to be the case.

All in all, it IS a mess. But more because it seems that nobody's ever done it before and so there is no experience to draw from. I scoured the Bentley last night for several hours and it shows that most of the coding problems point back to two sources: a significant leak (vacuum and/or boost) and the charge air sensor.

Maybe I'm the optimist, but it runs so close to OK that I can hardly believe that the problems are not fixable . . . the variable cam timing is the wild card. If I can nail down the other two issues maybe the direction on that one will become more clear?

Thanks for your ideas and help on this.

RoberTT-WWCD

if just the block was replaced, everything should be as it was. On the other hand, installing the whole engine could have problems as mentioned above.

You could have a vacuum leak that would cause the problems you have described.

The varible cam thing is something i'm not to keen on as I have a ATC engine.

I don't remember if you bought the car from an Audi dealer. If so, take it back to them and have them fix it. Just my $0.02.

Good luck

BDubya

The work was NOT done at an Audi dealer--I came into the picture after the fact. My understanding is that it was basically a longblock/head swap out--the timing belt had broken and the head/valves were shot, along with several pistons. They felt the swap was better than changing parts. Supposedly they called Audi for the replacement part numbers, but I can't believe that AofA would have given them 'AWP' when it's obviously an 'ATC' car. The bottom line is that the turbo/ECU/plumbing/wiring are all from the original car.

A series of phone calls have located the original block, although it's now an hour-plus away. I have made arrangements for Saturday to go inspect it and will have a better idea then as to the exact parts that were changed.

This certainly has given me a new hobby!!

Thanks