Engine Conversion: How-To Guide & Tips

I'm having the following problem with my A3:

My original, modified engine (ALH, 11/1998, 66kW) no longer had the same performance after a turbo failure (who knows what else might have broken?). Therefore, I decided to replace the entire engine and now have the newer TDI, type ASZ (10/2001) with 96kW installed. This went well with some modifications and adjustments. However, the immobilizer turned out to be a problem.

Once everything was changed, the engine started perfectly. Unfortunately, the WFS (presumably referring to a diagnostic system) probably thought something was wrong and shut off the engine after just one second. I then tried to adapt the engine control unit to the WFS of the Generation II (I believe it is Generation II, as it's from 1998), but there was no way to do it!

Unfortunately, I have to admit that I purchased the engine control unit separately from a salvaged vehicle that was declared a total loss. This means that there are some errors in the non-volatile memory that cannot be erased! There were also problems when trying to reprogram the unit from automatic to manual transmission. The engine control unit simply wouldn't accept the change. Could this be related to the total loss, or is there another reason for it? Surely there must be a way to adapt an engine control unit from 2001 to an older immobilizer system. Usually, backward compatibility is common in electronics, or am I mistaken?

The fact is, I currently have a completely functional vehicle sitting around, which is not usable at all due to problems that I cannot resolve!

Hello,

Which errors in the engine control unit (ECU) cannot be cleared (error codes)? And what code did you use to attempt the reprogramming from automatic transmission to manual transmission?

'I believe the remapping was from 00001 to 00002! But I'm not the expert on this, I'm just assisting. And the non-erasable errors were related to the crash signal and the airbag. Unfortunately, I don't have the error codes at the moment, but I might be able to obtain them.'

Hey Diesel Aunt!
I know that problem all too well. I experienced something similar after I converted my car from gasoline to TDI. According to Bosch service, the immobilizer (WFS) and the engine control unit (ECU) are essentially linked. So, I had to install the immobilizer from the donor car (the one I used for parts) into my car as well. This resulted in having two immobilizers. However, after that, everything worked fine.
Best regards from Bielefeld.

Peter.

Hmmmm....
'Well, this is certainly a tricky situation! Are you absolutely sure that I only need to install an additional immobilizer? I actually thought the immobilizer was integrated into the instrument cluster! And if I replace the instrument cluster, there's a chance I might also need a completely new wiring harness, right? The ignition switch with the reading coil would also likely be affected. And if I'm unlucky, the instrument cluster from 2001 might not even fit into the dashboard of the 1998 model, which would mean I'd also need a new dashboard...'
Right now, this whole situation is really getting too big for me.
Is there really no other solution?
Perhaps it can be disabled by modifying a chip in the control unit to prevent WFS queries.
Has anyone really attempted this renovation before me?

And if that's the case, I would need both WFS and STG from the same vehicle, if I understand you correctly?

Will you be getting a TÜV inspection for all the modifications? I would suggest looking for a replacement engine control unit (ECU) and a replacement combination instrument at a recycling center.

I've actually been thinking about that too, but it was supposed to be the last resort. After all, it also involves certain costs. And to be honest: I wanted to keep those costs as low as possible! But I'm really starting to think that it might not be possible.

Okay, the TÜV inspection. I'm hoping it goes well; I've done some research beforehand. Apparently, there should be a certificate of conformity from Audi based on the existing production model. With that, the registration process shouldn't be too difficult. But I'll just let everything unfold for now.

Unfortunately, I can only repeat what the Bosch Service stated, which is that the relationship between the WFS and STG systems is, at least in the Volvo 850, akin to a marriage. I was quite relieved to have acquired a complete wreck, as it meant I could spend a few more hours tracing and connecting wires.
The TÜV (German technical inspection authority) registration was no problem at all. I took the documents for the TDI engine and my own documents to the TÜV, someone took a look, tested the brakes because of the vacuum connection, and then there was some paperwork, which was well-paid. But that was it, all done. It's quite a difference whether I burn 7.3 liters of diesel or 11 liters of gasoline every 100 km... However, I'm now also missing 65 horsepower.
Best regards from Bielefeld.

Peter.

@Peter!

How about a chip?

Best regards,
Uwe.

So, I also called Bosch customer service today. They also pointed out to me that there was 'almost no' - but I think rather no - chance!
Well, I later called RAR. Maybe you're familiar with them! In my opinion, they're a very competent recycling company. During the call, I happened to find out that the company itself had already carried out a very similar renovation, and I can call them again tomorrow to discuss some details.
Anyway, my new combination instrument is arriving on Friday, and I'm a bit more optimistic again after today's statements!
I'm curious to see if I'll be able to drive again soon...
As soon as the car is running, I'll probably write a complete report about the experience – then those who follow in my footsteps can get an idea of what to expect. Such a report would definitely have saved me some trouble!
What's the matter? Even like this, it's always fun!

If the old instrument cluster works with the new control unit, then there's a good chance that the new control unit will also work with the old wiring harness.

It wouldn't be straightforward to do that with a VW Golf, because the PIN configuration has changed. You would then constantly receive 'brakes worn' messages, and the preheating light wouldn't work correctly.

What also didn't work for me when I replaced the old combination instrument cluster with a new one was the tachometer. But you certainly don't need to replace the entire wiring harness; you probably just need to install a new connector.

At VW, the 'Generation II' model was sometimes available from September 1998, but in some cases, not until May 1999.

Good luck .
Please tell us how much all this fun cost you and how much effort it involved!

Hi Diesel Aunt, get in touch with me. Apparently, the WFS issue should be resolved.

arne