Another S4 avant swap in the works - Build Thread

[rand0mher0]

Cross posting this from the B8 S4 forum to reach more people

Hello all! Over the past few months I have been planning my S4 avant swap and it is finally starting this weekend.

The avant had to have the s-line exterior package so it would look the part, and the s-line interior with the black headliner was not a deal breaker but would be nice to have. Late last year I found and purchased the perfect candidate for the swap, a B8 A4 avant prestige in brilliant black with the full s-line exterior / interior package.

So then I set out to troll the auctions and find a lightly wrecked S4 sedan with similar options to my S4. Thankfully that did not take long and 2 weeks ago I picked up a 2010 S4 prestige with some light suspension damage from hitting a curb. This S4 is still a baby with 103k miles and has all of the right options including
-6 speed manual transmission
-Sport rear differential
-Adaptive suspension
-Bang & Olufsen
-Navigation
-Advanced Key

Over the next few weeks I will gut the S4 completely and transfer everything into the A4 Avant so when I am finished it will be a complete running and driving 3.0t 6-speed S4 wagon with all of the above features. I have already torn down the interior of the wagon. Tomorrow I start stripping the S4 and over the next few days I will dismantle and strip the Avant. I will be using my buddy's shop space and will have a lift for this.

My timeline is:
Tomorrow - Drop engine, transmission (as one unit), rear subframe / sport diff from the S4
Saturday - Strip interior and pull body harness
Sunday - Finish up S4 and pull in A4, begin to prepare to drop drivetrain
Monday - Drop drivetrain from A4, pull body harness

Over next week I will section over what I need from the avant harness and move it over into the S4 harness. Then put the wagon back together over the next few weekends. The goal is to have this running and driving by the end of March and drive it down to Helen, GA in May for Alpine Volks Fair

I will update this periodically as I have time, but for more frequent updates. Follow me on Instagram at @rand0mher0

- - - Updated - - -

The candidate car:


The donor car:


The current state of my avant:

[KSEADUB]

Subbed!


Sent from my iPhone using Tapatalk

[drewgold]

So awesome. Stoked to see how it all goes!

[hardfive]

Have fun. Lmk if you have any questions along the way.

Sent from my SM-G973U1 using Audizine mobile app

[Chatchie]

Can you document the wiring if you have a chance. Especially any splices/additions you have to make to the S4 harness to integrate the allroad electrics.

I was gonna go K04 but for the money I think this looks better. Mind saying what you paid for the S4?

[rand0mher0]

Thanks all for the positivity! While I didn't get everything done that I had intended to this past weekend, still made great progress. The S4 is 100% stripped. Taking a break this week and then going back at it on Friday to strip the wagon.

Started late Friday night and had the engine / trans dropped by 1am.



Started early saturday morning and dropped the rear subframe with the sport diff and suspension. Started stripping the interior and getting ready to pull the body harness



Pulled the dash bar with harness on Sunday and started unclipping the body harness



and finally on Monday I pulled the manual pedal cluster, brake booster / master cylinder, clutch master / slave cylinder and finally pulled the body harness the rest of the way.







I am exhausted! Lol I have about 23 hours into this so far. Can't wait to get the other body harness home and get this wiring over with.

[rand0mher0]

Can you document the wiring if you have a chance. Especially any splices/additions you have to make to the S4 harness to integrate the allroad electrics.

I was gonna go K04 but for the money I think this looks better. Mind saying what you paid for the S4?

The car receiving the swap is a b8 A4, not allroad so the wiring may be a little different for you but same premise. So far I have remove the trunk portion from the S4 harness and add in the hatch wiring from the A4 harness. Also the subwoofer and rear b&o speakers are in a different location. The wiring going to the sunroof controls need to be changed as well for the extra wiring for the power sun shade. I was also under the impression that the antennas are different but I won't know exactly what I have to change until I get both harnesses out and next to eachother. I will definitely document all wiring changes I have to make to the harnesses.

My winning bid on the S4 was $6,000 and paid just under $7300 after copart and broker fees.

[unitzero]

This is awesome. Good luck with the rest of the swap


Sent from my iPhone using Tapatalk

[eljay]

Looking good so far!
Like a Lego Technic for adults.

Now, those S5 rotors don't look good anymore, so you need to sell them to me, ok?!

[rand0mher0]

Put another 20 or so hours into this this past weekend...
Pulled the motor from the avant on Friday night in a few hours




Pulled the rear diff / subframe on Sat morning, then pulled dash, dash bar, steering column and pedals / brake booster






We threw in the 3.0t / 6 speed and rear subframe into the wagon. I will have to pull the motor back out to do the clutch and gutted cats, but the goal this weekend was to get the body harness out and make the shell rollable again. So I ran out of time to do the maintenance needed and its 30 min to get the motor in / out so not a big deal to pull it again next weekend.




I got the remainder of the body harness out on Sunday and threw in the pedals and steering column for shits and giggles :D






Now I have both wiring harnesses at home with me so I get to play wiring this weekend and hopefully have the harness ready by next weekend!

[DownhillA4]

Love it, Matt! Can't wait to see it all finished. Props on this job!

[Chatchie]

Looks like an awesome project. I'm about to break ground to finally get my garage built. I think this might be a good project on my shiny new lift.

[Jdsb6s4]

Excellent stuff!

[asal]

utter amazement at the work that goes into this. Totally want a 6-speed 3.0 Avant though!

[rand0mher0]

Mid week update to show the mess I'm currently dealing with sorting through connectors from the rear hatch harness and tracing them back to where they terminate. Doing this without wire diagrams so I am making my own pin out sheet of what I need and then will de-pin from the avant harness, will de-pin the matching location on the s4 harness and then will re-pin the rear hatch harness into the s4 harness.

The rear hatch portion of the harness unwrapped and the rear body control module / fuse panel


An overall shot


And a preview of the unfinished word doc of the wiring pin out for the rear hatch harness

A4 Harness
Passenger Outer Tail light – 4 pins
1 – Ground
2 – Black w/ Yellow trace (pin 30 black rectangle connector BCM 2)
3 – Black w/ White trace (pin 1 black square connector BCM 2) 
4 – Black w/ Green trace (pin 12 Tan connector BCM 2)
Driver Outer Tail light – 4 pins
1 – Gray w/ black trace (pin 6 tan connecter BCM 2)
2 – Black (pin 14 tan connector BCM 2) (will have to splice in)
3 – Green (pin 31 black connector bcm 2)
4 – Ground
Driver Inner Tail light – 4 pins
1 – Black w/ blue trace (pin 12 black square connector BCM2)
2 – Ground 
3 – Gray (Pin 11 tan connector BCM 2)
4 – Gray / Purple w/ yellow trace (pin 5 tan connector BCM2)
Passenger Inner Tail light – 4 pins
1 – Gray w/ white trace (pin 13 tan connector bcm2)
2 – Ground 
3 – Gray (pin 10 black square connector bcm2)
4 – Gray w/ blue trace (pin 11 square connector bcm2)

Rear liftgate button – 4 pins
1 – White / pink (pin 8 tan connector BCM 2) – Shares power going to pin 8 bcm 2
2 – Gray w/ black trace – (to liftgate motors)
3 – Ground 
4 – Ground 

Liftgate motors – 8 wires
Red w/ yellow trace (to fuse panel 30amp fuse)
Red w/ white trace (to fuse panel 30amp fuse)
Ground (big)
Ground (big)
Ground (small)
White / pink ish – (liftgate button to BCM2)
Orange w/ green trace (Pin 19 black rectangle connector BCM2) (will have to splice)
Orange w/ brown trace (wrapped with above) (Pin 20 black rectangle connector bcm2) (will have to splice)

Rear body latch / motor – 5 pins
1 – Gray w/ blue trace (pin 2 black square connector BCM2)
2 – Gray w/ yellow trace (pin 3 black square connector BCM2)
3 – Gray w/ black trace (pin 20 blue connector BCM2)
4 – Ground 
5 – Gray w/ white trace (pin 5 blue connector BCM2)



Back up camera plug – 2 pin
1 – Red w/ blue trace (pin 48 back up cam module)
2 – Brown w/ blue trace (pin 47 back up cam module)

Rear hatch release button (outside) – 2 pin
1 – Ground 
2 – Yellow w/ Green trace (pin 3 gray connector BCM2)

Rear hatch latch – 4 pin
1 – Green w/ yellow trace (pin 4 gray connector BCM2)
2 – Green w/ black trace (pin 8 gray connector BCM2)
3 – Ground
4 – Green w/ red trace (pin 5 black square connector BCM2)

Rear wiper motor

Pass License Plate Light

Driver license plate light

Trunk hatch light 

Third brake light

As noted in hardfive's thread here: https://www.audizine.com/forum/showt...1#post13999423

He noted that if your BCM2 is missing the pins in the bottom left (blue) connector, you can not re-use the module (if you intend to use the power lift gate). My donor S4 and my personal S4 both had these pins (thankfully). I am 99% sure if the s4 has kessy (advaced key), those pins are there as both my donor and personal S4 have that option. So that's one annoying roadblock solved, I should be able to re-use the S4 BCM2 and just simply recode for the lift gate. Will confirm this when the harness is complete. But I am 99% this will work.

[audiphila]

You may be the first one to have a working rear wiper!

[rand0mher0]

You may be the first one to have a working rear wiper!

That'd be nice but it's not world ending to me, lol. I was probably gonna delete it anyway and just add rain-x to the rear window. That reminds me I have to check the steering column wiring to see if there's any extra wiring for the wiper stalk. I know on the b7s whether you got the trip computer or not, the wiring was there so I am hoping it's a similar situation on this car, doubt it though lol. Will have to see where the rear wiper wiring terminates.

[avantagg]

This is AWESOME!!! Congrats man. It's gonna be a beast. Subd!

[rand0mher0]

This is AWESOME!!! Congrats man. It's gonna be a beast. Subd!

Thanks man!!

Another update:
Finished up sectioning off the avant portion of the A4 harness on Friday, depinned it and it is ready to be transplanted into the S4 harness


Spent some time at the shop this weekend, dropped out the drivetrain of the wagon to do some maintenance items:
[img]Removed transmission to put in a brand new Sachs Xtend Clutch and OEM Flywheel (the old flywheel looked super crusty and burnt!)





The motor mount was not actually cracked like it appeared (just part of the design I guess) but the mounts definitely needed to be changed, as both sides were split as seen in the pics. Replaced them with 034 Motorsport Street Density Mounts



Replaced the cats with a set of gutted cats (obviously can't tell from the photo but they are gutted!) I also had the flanges welded on the outside because apparently they are susceptible to cracking after they are gutted?



After that I mounted the drivetrain in the wagon for the last time! I plan on finishing up wiring either today or tomorrow, and going up on Wednesday to put as much together as I can. Would like to have it running Wednesday if possible and driving this weekend

[rand0mher0]

Big update, wiring is in and the car runs and drives! Have a few faults I need to clear up, and also clean up the rear hatch wiring, but other than some faults as a result of having no interior, everything seems to be up and running great! I took it on its maiden voyage from the shop to my house (2 hour / 130 mile) and it made it hiccup free so I am thrilled. Now the car is back home and I can chip away at it during the week to get it 100%.

A few problems:
- An EPC / TC / Sports diff fault I need to sort out that seems to be related to the steering.

- The advance key / keyless functions are not working. I can not open it from the door handle or even unlock the car via the key fob, have to use the key blade in the door. The interior key detection was spotty the first time I started the car (press the start / stop button and no key identified appears on the dash) but it was working initially.. It's weird because when I touch the door handle or push start / stop button, the key does light up as if it is being interacted with but nothing happens. The only thing that did not get swapped from the donor s4 was the door modules (have these) and the door handles (don't have these). Sooo not sure if the modules have to be swapped or what but there is some disconnect there.

-I redid the adaptation in the BCM2 to try to make the halogen tail lights work and it did help but they are still off. (Brake lights sometimes just stay on, or don't work. Right turn signal uses the outer tail light and inner fog light bulb, left turn signal uses just outer tail light.) In the process of buying b8.5 led tail lights. Hopefully they rewire and adaption from that will correct this issue.

-I also tried recoding the BCM2 to tell it it has a power liftgate now and that the car is a wagon, but it was asking me for some workshop code and was rejecting the coding so I'm not sure what's up with that. Will probably visit my friend at the dealer and see if he can manually recode it with ODIS. Good news is the lift gate works and opens, just doesnt close when I hit the button. I have to close it manually.

Onto photos (these are spotty because the camera on my iPhone XS died and had to use my shitty iPhone 7 for this):

[jaustin]

wow just beautiful!

[northnj]

Congrats, dude! Accomplished quite a lot in a short period. Good luck with sorting out the rest of the issues.

[audiphila]

Damn! Making good time with this.

I think you need the door handles for the kelyless entry to work. I’m pretty sure they are paired to the key fob and sensors. Do you get ignition key fault error in the cluster?

You may need a new brake light switch or adjustment in the brake pedal for the light not working right. Mine wouldn’t Come on unless I pressed really far down on the pedal which caused the brake light switch to fail. No problems after adjusting pedal and replacing switch.

I had bulb out errors when I did the led taillight and headlight facelift but was able to code them out by adjusting the brightness

Good luck and looking forward to clips of her running!

[rand0mher0]

Thanks all!! Yeah crazy to think this was done in 3 weeks. Could have been done faster too if I wasn't doing this on just weekends.

Double checked the adaptation channels, I messed up one of them and put "13220" instead of "13320". Left outer tail light turn signal now functions, but the rear fogs are still acting as the running light / turn signal. I think the wiring may have changed from 2009 to 2010. Either way it works enough, and it's getting updated to B8.5 euro led tail lights any way so that should take care of that.

Also ordering a brake light switch which will fix the intermittent brake lights and I am hoping that is the source of the TC / ESP / Sports diff faults because those come up randomly. There was a brake light switch fault in all of the major modules (ECU, ABS, AWD etc). Just cleared faults, took it around the block and the faults don't come back right away. They came up when I was slowing down towards a stop sign. Which was a similar situation to when they appeared originally. So my theory is that it's losing communication with the brake pedal switch and the traction control is freaking out along with the other modules. Will report back if the brake light switch fixes it.

Damn! Making good time with this.

I think you need the door handles for the kelyless entry to work. I’m pretty sure they are paired to the key fob and sensors. Do you get ignition key fault error in the cluster?

You may need a new brake light switch or adjustment in the brake pedal for the light not working right. Mine wouldn’t Come on unless I pressed really far down on the pedal which caused the brake light switch to fail. No problems after adjusting pedal and replacing switch.

I had bulb out errors when I did the led taillight and headlight facelift but was able to code them out by adjusting the brightness

Good luck and looking forward to clips of her running!

I'm going back up to the shop tomorrow to grab the handles off of the donor car before it gets scrapped. I will throw those on the wagon and see if that fixes it. No ignition key fault in the cluster, only a "No Key Identified" when I push the start / stop button. Sometimes it'll randomly work but I haven't gotten the handles to work.
I also surprisingly don't have any bulb out errors either. I think I either just wired them wrong or the wiring changed from 2009 to 2010 or from Wagon to Sedan or some combination of that.

[rand0mher0]

Well much like hardfive.. my keyless just randomly started working. Starts everytime now without having to use the receptacle in the dash, also the touch sensors work on the doors, and can unlock / lock from the key. I plugged in the rest of the airbags and put the glove box in, cleared faults and then it started working.. so bizarre. I did end up grabbing the door handles from the donor s4 this morning before it gets scrapped.. turns out I didn't need them!

Some pictures because what's a thread without pictures. Starting to look like a complete engine and car again:




I still have to tidy up some wires in the trunk area before I put the rest of the trim panels on so that still looks like a mess. And since the B8.5 LED upgrade / rewire is imminent I am waiting to do that before that's done.

[jhoward]

Damn that’s a project!


Sent from my iPhone using Audizine

[rand0mher0]

Got the brake light switch in today and as expected, it took care of the remaining faults. Now all that is left is to figure out the rear hatch situation.

No lights!

[Chatchie]

Well done sir. You didn't eff around at all. Very jealous, appreciate you documenting what you could.

[rand0mher0]

Well done sir. You didn't eff around at all. Very jealous, appreciate you documenting what you could.

Thanks man! I still plan on putting up the wiring that I had to section over. There were 1 or 2 differences from 2009 to 2010-2012 so I am confirming those. Although it would not be helpful to you being that you are b8.5

I was able to get my hands on the Kufatec PDF for the power lift gate retrofit and I found one wire to be different for the rear latch / motor on the body. I will make that change today to my harness and see if it helps any but I am starting to think I will just need to use the a4 bcm2.

[audiphila]

Very jealous of the fault free cluster! You made this look easy. Hopefully when our wagons get together we can compare adaptations and I can sort mine out too. Best part about this swap is that it is Manual trans! You will have so much fun rowing through the gears whiles hauling stuff! I wouldn't even bother with this swap unless there are 3-pedals in the end result.

[rand0mher0]

Very jealous of the fault free cluster! You made this look easy. Hopefully when our wagons get together we can compare adaptations and I can sort mine out too. Best part about this swap is that it is Manual trans! You will have so much fun rowing through the gears whiles hauling stuff! I wouldn't even bother with this swap unless there are 3-pedals in the end result.

We definitely gotta make that happen soon!

Small update: still no dice on the rear hatch. I can not get the S4 bcm2 to take the coding. I think it may be software that is telling it, it can't take that coding even though it has the pins for it. May need the dealer to do it, but my in at Audi is now out of work due to the virus BS. I ordered the knockoff vas5054a odis cable in hopes that Jack can remote in and work his magic and get it to take the coding or program the a4 bcm2 to work. As of right now I can't even get my car to power on with the a4 bcm2 plugged in. Not sure if it's component protection causing that or some other incompatibility.

In case anyone is wondering, I figured out how to reset the keyless system and get everything to work (if there are no other faults). Just unplug the bcm2 for a period of time, lol. The keyless stopped working again after I plugged in my a4 bcm2 and then s4 bcm2 back in. I had to unplug the s4 bcm2 completely and let it sit for like 2 hours. Plug everything back in, and then start the car for the first time using the receptacle in the dash (this is how it learns the key). After that, the remote and advanced key functions started working perfect.

[Chatchie]

God damn it I want one! I wonder what these are gonna be worth when people start selling. I need a manual allroad in my life.

[eljay]

God damn it I want one! I wonder what these are gonna be worth when people start selling. I need a manual allroad in my life.

Me too!
I may settle for a manual swap on my Allroad down the road and just stick with Stage 1 tune. The 3rd pedal shall provide sufficient smiles per gallon.

Gotta do it quick before we get used to the ZF8.

[Chatchie]

Me too!
I may settle for a manual swap on my Allroad down the road and just stick with Stage 1 tune. The 3rd pedal shall provide sufficient smiles per gallon.

Gotta do it quick before we get used to the ZF8.

Actually I'd prob be happy with the manual swap and KO4. B8.5 A4 came with a manual right?

[eljay]

Actually I'd prob be happy with the manual swap and KO4. B8.5 A4 came with a manual right?

Yes, A4 sedan did, Allroad did not.

S4 swap is not cheap and requires lots of labour, but looking at the total cost (hardware/software), I'm not sure K04 makes much sense to end up with a 4-cylinder with the same headline HP number as stock 3.0T, but compromised driveability.

[rand0mher0]

Yes, A4 sedan did, Allroad did not.

S4 swap is not cheap and requires lots of labour, but looking at the total cost (hardware/software), I'm not sure K04 makes much sense to end up with a 4-cylinder with the same headline HP number as stock 3.0T, but compromised driveability.

Labor is the real problem here. I paid $7300 for my parts car which is high, but I knew I was buying the right car. Very easy to get a good donor car for $3000-$4000 usd. If you have a shop do the work, labor is going to far exceed the cost of the car, which sucks.

I have about 115 hours into this right now. $7k cost for the wagon and $7300 for the donor car, maybe $2k in parts. I don't even want to know what the bill would have been from a shop, lol. If you can do the work yourself, it is so worth it.

[audiphila]

115x $200/hr = $23,000 (obviously $200 is high) +
$7,000 for Avant +
$7,300 for s4 donor +
$2,000 misc = $39,300.00

That is not inexpensive, but doesn’t seem like an unreasonable number to an enthusiast for a used s4 Avant that doesn’t exist in the USA. Look at the bring a trailer prices for s4 Avants lately.

I agree with randomhero that the MANUAL trans and 3.0 engine is the real reason to justify this swap. Bonus if you can do the work yourself.

Fortunately, the more swaps happen, the more info there is to make the swap easier and with less hiccups/unknowns.

Thanks random hero and this forum for taking the time to document your work so the rest of us can benefit

[eljay]

No doubt that it isn't cheap.
I know that one can just give a shop $5k and pick up a buttoned up K04 car few days later.
But I would rather spend that $5k on a donor car and snowball into thousands from there! LOL

[avantagg]

It’s an insane amount of work, especially for that coveted third pedal. Just completed one recently here as well ( gasp DSG ). Huge props to @rand0mHerO for completing this on his own (that rewire looked painful!), and to some of the guys who recently completed and shared info on theirs. Wish i had the space and time to DIY mine but i let a shop handle it and it was definitely worth it.

[rand0mher0]

The magician Jack Kirry helped me out this morning and adapted my A4 BCM2 to my car. Rear hatch functionality is back. I also removed my 3G+ MMI from my S4 to get it ready for sale and installed it in my Avant so Jack could remove the component protection from that as well.

As of now the only things to sort out are:
Waiting on Euro LED tails
Waiting on Fakra extension cables to plug in the Sirius / Cellular from the MMI to the shark fin
Need to figure out radio antenna (will likely try to source a complete harness from a 2010-2012 avant as the 2009 mmi / radio antenna was vastly different)
Sunroof needs basic setting
Need to wire in rear wiper now that hardfive solved the rear wiper mystery

Other than those few small items, the car is 100% functional. Have about 1500 miles on it so far and am loving it. I bought CTS crank and super charger pulleys for it while they were on sale. Will be purchasing the IE double pulley tune soon.

Some pics: