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View Full Version : 4.2 and Tiptronic...what could possibly go wrong??



wolfe2118
01-09-2019, 07:08 AM
The wife's 1.8T B5 let go today while on her way to work. She told me that she got off of the highway and it wouldn't stay running and when I came to pick her up it was making all kinds of noise, low oil pressure, and smelt really hot so it's safe to say the engine is toast (it's still sitting at a gas station).

She loves the sound that my V8 B5 A4 makes and I just happen to have an extra engine, ECU, wire harness, mounts, radiator...literally everything needed to do the swap. Buuuut she will not daily drive a manual because it's too hard to backhand kids in the back seat while also shifting gears, she doesn't want to wait to beat a child until she finishes a turn. (I made that up..actually she just doesn't want to learn to drive it). My thoughts are that my A4 with a AWN 4.2 and a 6spd manual gets equal fuel mileage as her 1.8 A4 and requires less maintenance so why not try something new....whats the worse that could happen? I end up pulling the 4.2 and replacing it with a 1.8? She becomes the baddest 1st grade teacher driving a V8 swapped A4? She grenades the Tiptronic and *gasp* learns to drive a stick?

Sooo...today will be the start of my AWN swap into a Tiptronic car while retaining the Tiptronic. I know this will probably not end well and even if the engine and transmission do play well together, the transmission will probably not last very long however in my field of work (engineering) I am always trying new things even when the rest of the industry says it's a bad idea.

Has anyone else even attempted such a thing?

101069

Blazius
01-09-2019, 07:57 AM
you crazy. go for it :D

walky_talky20
01-09-2019, 08:21 AM
This is a terrible idea. Subscribed. [up]

But honestly, I think it will bolt up and move. My guess is that there will be an epic mismatch between the TCU you have and the TCU that the V8 ECU wants to see. Like, there is a super tiny chance it will be like "I guess we have gears, Lets Rip!" (translation: there is a chance that the communication protocol is fairly standard between Audi models of this vintage and uses generic data points like engine load percentage and torque amounts and doesn't care too much about specifics). But most likely it will be in a mega-hard limp mode before you even put it in Drive.

I guess what you *could* do is plug the V8 ECU / V8 engine harness into the car (ie: temporary wiring swap only), and see if the ECU throws a TCU communication code or not. If they link up and don't complain, you have a chance. A good test would be to see if the TCU can see the throttle angle (if pedal and throttle body are plugged in, obviously).

Otherwise you'll probably need some deep-dive ECU/TCU software changes to enable happy communications, or get a V8 TCU to work instead. The controls for the V8 trans (number of solenoids, etc) are probably similar enough that it could just work. But I think all the gear ratios would have to match or it will think it's slipping all the time and set faults. So this could turn into just using the entire V8 transmission. These break all the time, so that's probably not an easy or cheap option.

TLDR: You won't know unless you try stuff. I suggest trying electrical things before swapping the actual hardware, but that's up to you. Just know that you are blazing a trail here.

Fasterd
01-09-2019, 08:22 AM
Everything.

wolfe2118
01-09-2019, 09:05 AM
This is a terrible idea. Subscribed. [up]

But honestly, I think it will bolt up and move. My guess is that there will be an epic mismatch between the TCU you have and the TCU that the V8 ECU wants to see. Like, there is a super tiny chance it will be like "I guess we have gears, Lets Rip!" (translation: there is a chance that the communication protocol is fairly standard between Audi models of this vintage and uses generic data points like engine load percentage and torque amounts and doesn't care too much about specifics). But most likely it will be in a mega-hard limp mode before you even put it in Drive.

I guess what you *could* do is plug the V8 ECU / V8 engine harness into the car (ie: temporary wiring swap only), and see if the ECU throws a TCU communication code or not. If they link up and don't complain, you have a chance. A good test would be to see if the TCU can see the throttle angle (if pedal and throttle body are plugged in, obviously).

Otherwise you'll probably need some deep-dive ECU/TCU software changes to enable happy communications, or get a V8 TCU to work instead. The controls for the V8 trans (number of solenoids, etc) are probably similar enough that it could just work. But I think all the gear ratios would have to match or it will think it's slipping all the time and set faults. So this could turn into just using the entire V8 transmission. These break all the time, so that's probably not an easy or cheap option.

TLDR: You won't know unless you try stuff. I suggest trying electrical things before swapping the actual hardware, but that's up to you. Just know that you are blazing a trail here.I have the A6 tiptronic as well as the TCU but I would rather make the A4 transmission work if at all possible. The A6 transmission had some quirks when I drove it but after a fluid change they were gone. Even then I would rather use a transmission that I know is good and not replace it. The more I think about it (havent done too much research yet), the transmission shouldn't take too much of a beating with her driving it.

As of right now I just want to see if it's possible. I'll start on it tonight and at least get the engine mated to the transmission then I'll work on wiring next week. After that it will be put on the back burner until spring.



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Blazius
01-09-2019, 10:18 AM
Brother, get this: https://www.ecumaster.com/products/digital-ecu-tuner-3/


This will allow you to tune the car and drive it withouot breaking bank on standalone. You can set it up in fuel implant - basically standalone- mode driving the injectors off the unit instead of the ECU directly. You only need maf and crank sensor to run it pretty much.

You can find wiring diagrams for some cars on their website aswell as the software for both modes. You can find a 4 bar version one for like 300 usd on ebay.

wolfe2118
01-09-2019, 10:39 AM
Brother, get this: https://www.ecumaster.com/products/digital-ecu-tuner-3/


This will allow you to tune the car and drive it withouot breaking bank on standalone. You can set it up in fuel implant - basically standalone- mode driving the injectors off the unit instead of the ECU directly. You only need maf and crank sensor to run it pretty much.

You can find wiring diagrams for some cars on their website aswell as the software for both modes. You can find a 4 bar version one for like 300 usd on ebay.While that is interesting I don't need it, I can use the stock ECU. This will be my 4th 4.2 swap into an A4, just my first with a Tiptronic. That being said I used Megasquirt back in 2005 so if I was going to use anything other than OEM engine management it would be MS.

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walky_talky20
01-09-2019, 01:25 PM
Brother, get this: https://www.ecumaster.com/products/digital-ecu-tuner-3/


This will allow you to tune the car and drive it without breaking bank on standalone. You can set it up in fuel implant - basically standalone- mode driving the injectors off the unit instead of the ECU directly. You only need maf and crank sensor to run it pretty much.

You can find wiring diagrams for some cars on their website aswell as the software for both modes. You can find a 4 bar version one for like 300 usd on ebay.

Brother...bro...brah,

how is the TCU going to see RPM, throttle angle and engine load with a standalone setup like that? It critically needs that data stream to decide when and how firmly to shift. It also needs the Engine to respond to its timing retard requests (to cut power during shifts, and generally contribute to the doggy, rubber-band feeling of a tiptronic, which is likewise *critical*. lol)

Remember, this is a Tiptronic - not a Powerglide or a Turbo 400. It needs data from the engine to work. Unless you *really* like 4th gear and slamming Reverse like it's a MK4 Jetta on sawblades.

RENOxDECEPTION
01-09-2019, 02:03 PM
she doesn't want to wait to beat a child until she finishes a turn.

are we all just skipping over this? [>_<]

Best line in the whole post, excited to see progress!

walky_talky20
01-09-2019, 02:33 PM
^I lol'd at that as well. Too funny.

Fasterd
01-09-2019, 02:36 PM
False

Walky_Talky20 = Brother...bro...brah........


For the win

walky_talky20
01-09-2019, 05:21 PM
^lol. I had to read that few times before I got it. Thx.

Blazius
01-10-2019, 12:30 AM
Brother...bro...brah,

how is the TCU going to see RPM, throttle angle and engine load with a standalone setup like that? It critically needs that data stream to decide when and how firmly to shift. It also needs the Engine to respond to its timing retard requests (to cut power during shifts, and generally contribute to the doggy, rubber-band feeling of a tiptronic, which is likewise *critical*. lol)

Remember, this is a Tiptronic - not a Powerglide or a Turbo 400. It needs data from the engine to work. Unless you *really* like 4th gear and slamming Reverse like it's a MK4 Jetta on sawblades.

True I did forget for a sec that this automatic cr4p , my bad :D

walky_talky20
01-10-2019, 08:31 AM
No worries, this is a unique swap. There are a lot of unknowns. How picky is this TCU stuff going to be? Nobody really knows. Like, we don't even know the implications of using a different physical trans code in a typical replacement scenario. This swap is all of that...x10.

Blazius
01-10-2019, 08:46 AM
Also I've heard the automatic breaks at like 300 HP, and stock 4.2 makes like 340 hp already ? Gunna have to see.

wolfe2118
01-10-2019, 08:52 AM
No worries, this is a unique swap. There are a lot of unknowns. How picky is this TCU stuff going to be? Nobody really knows. Like, we don't even know the implications of using a different physical trans code in a typical replacement scenario. This swap is all of that...x10.Let's just hope that to the ECU/TCU rpm is rpm, the difference in ratios are within the normal prefault tolerances, and it doesn't get too upset by the different final drive ratios. Expanding on hypotheses, if you make more power in a 1.8t bu way of engine modifications the tiptronic transmission still operates as expected so the additional force made by the the V8 shouldn't play a factor and since the valve bodies are very similar it should all come down to how well either TCU (I have both the A4 and A6 units to try) can adapt.

As far as durability is concerned, I don't care. That is not even a factor to me, I'm fully prepared to smoke the clutch packs, damage the spraggs, and destroy the linings on the torque convertor. I'm not even expecting it to work but I have everything I need to do it so why not.

Lately I've been learning a lot about the electronics and programming side of cars so this could be an opportunity for me to expand that potential into TCU operation and programming.

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Blazius
01-10-2019, 09:25 AM
Does it have an ME7 or me3 ECU ? What year is it and dbw or not ?

walky_talky20
01-10-2019, 11:06 AM
Interestingly, the included photo of the car gives us zero indications on whether it is a '99.5, '00 or '01. We just can't know. With any luck, it will be a model year match with the donor A6. That would be best case.

Blazius
01-10-2019, 11:44 AM
Well the headlights are definitly look prefacelift, but I cant make it out if they are 2 piece or not. if its a 2000 then you might have mismatch , 2k was a heavy hybrid year for VW.

walky_talky20
01-10-2019, 03:26 PM
We can tell from the door handles and side turn repeater lights that it's a 99.5 or up. But the sole exterior indicator for whether its DBW or not would be the size of the right hand mirror, which is unfortunately not shown in the photo. So we wait...

wolfe2118
01-10-2019, 07:02 PM
2001 AWM engine.
This weekend I will have the 4.2 in and running. I'm going to rig up the a6 radiator without the support, bumper, or headlights just to drive it up and down the road without hacking up the core support. I think I'm going to wedge a cut out piece of tire sidewall and wedge it between the crossmember and oilpan so I don't have to cut it up for nothing if the transmission doesn't like the engine.
For now I'll be running nothing but a set of my downpipes with a xpipe muffler hanging under the car. I don't want to do fabricate anything drastic unless I know the combination has a chance. I've decided that swapping in the A6 transmission isn't worth the hassle so if the A4 transmission will not work than its back to the 1.8t. I assume I'll know really quick if it has a chance of working.

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Mattr567
01-10-2019, 11:09 PM
Curious to see where this goes!!

What's next, a fwd A4 4.2 swap? [>_<]

Blazius
01-11-2019, 01:04 AM
2001 AWM engine.
This weekend I will have the 4.2 in and running. I'm going to rig up the a6 radiator without the support, bumper, or headlights just to drive it up and down the road without hacking up the core support. I think I'm going to wedge a cut out piece of tire sidewall and wedge it between the crossmember and oilpan so I don't have to cut it up for nothing if the transmission doesn't like the engine.
For now I'll be running nothing but a set of my downpipes with a xpipe muffler hanging under the car. I don't want to do fabricate anything drastic unless I know the combination has a chance. I've decided that swapping in the A6 transmission isn't worth the hassle so if the A4 transmission will not work than its back to the 1.8t. I assume I'll know really quick if it has a chance of working.

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so ME7, that is a bit optimistic IMO. Thankfully the ECU is almost the same as in the S4, and is very modular I think you will be able to make it work. But you gonna destroy 3rd gear in the 1st pull :D.

wolfe2118
01-11-2019, 03:01 AM
Curious to see where this goes!!

What's next, a fwd A4 4.2 swap? [>_<]Not from me. I'm not a fan of FWD.

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wolfe2118
02-06-2019, 10:40 AM
This project has been scrapped. I had a timing chain adjuster break on my B6 that caused the chain to skip and destroy a valve (zero compression on #6 cylinder) so I am using the extra engine for it's head. Because I no longer have an extra engine, it makes no sense to try the swap "just because I can" so I will be replacing the engine with another AWM with all four connecting rods intact. Sorry for getting anyone's hopes up!

A4 2.5TDI
02-06-2019, 12:50 PM
I was already excited that the tiptronic will explode and shred itself to bits but looks like no fun for me. Just kidding it would be a nice car if it would work.

Blazius
02-06-2019, 12:54 PM
This project has been scrapped. I had a timing chain adjuster break on my B6 that caused the chain to skip and destroy a valve (zero compression on #6 cylinder) so I am using the extra engine for it's head. Because I no longer have an extra engine, it makes no sense to try the swap "just because I can" so I will be replacing the engine with another AWM with all four connecting rods intact. Sorry for getting anyone's hopes up!

heh, that sucks , good luck !