but always felt like there was something missing. That gap has been filled with the B6 2.7T
motor swap, and this is EVERYTHING you need to know.
What is the 2.7T?
It's basically the V6 version of a 1.8T, with not 1 K03, but two (AWESOME).
What years was it made? In North America, it was made from 2000-2004 and here are the differences
2000: Bosch MAF, bolt down coils, no immob
2001: Hitachi MAF, bolt down coils, no immob
2002: Hitachi MAF, bolt down coils, no immob (ther
2003 (A6): Hitachi MAF, push down coils, immob, SAI (which sucks)
2004 (A6): Hitachi MAF, push down coils, immob, SAI (which sucks)
So which one should I get?
Honestly, this is preference. The 03-04 do have the push down coils and better ECUs, but this involves getting the immob defeated and also the tuning support sucks, so you are better off getting a 2000-2002 A6/S4 harness&ECU and going from there. The A6 and S4 are identical in parts so no difference between which one you get. Also, you can run any 00-02 ECU with any 00-02 harness. I would recommend getting a manual harness but it's not the biggest deal if you can't.
Is it easier to get the whole car or just the motor?
- Honestly you need nothing else from the car so I would look for a COMPLETE motor. You'll end up paying a LOT of money if you don't get something that's complete.
How much should I pay for the motor?
- This has a million factors at play, but a normal 2.7T goes for between $1200-2000. I paid $1200 but then had to get an ECU/fan module/etc.
- Also, the junkyard has a ton of these engines now. Generally if the timing belt is good and the car looks like it was totaled for other reasons, you can get a whole setup for $300-500.
What do I sacrifice with a swap like this?
- Absolutely nothing if you don't want to. All my gauges work, no CELs (due to the swap), and it drives like it was meant to be there. Cruise control is optional, and I haven't done it, but it can be done.
What do I need from said A6/S4 for all platforms? (parts by platform will be split up later)
- Entire Motor (EVERYTHING)
- Trans Plate between 2.7T and transmission (01E103551C)
- Harness/ECU from the 2.7T
- A6/S4 power steering line
- A6/S4 SMIC brackets (if you don't want to run a FMIC)
- Snub mount bracket (one that attaches to the motor)
- Fan Control Module/Harness (unless you want to go some custom route)
- Alternator/Starter wire from the battery down the passenger frame rail
- Some kind of downpipes that fit. I've heard SSAC do, stock downpipes DO NOT
Which car should I start with?
This is also a tough question because it's preference. The easiest one BY FAR is the 3.0 because of the engine mounting, fuel system, A/C, radiator. The 3.0 block is basically just an aluminum 2.7T so it makes things easy. Some may prefer the 1.8T because you can get them cheap nowadays and some may prefer the S4 for the seats/brakes/bumpers/obviousthings/etc
Will I pass emissions?
While emissions varies state to state and technically putting an older motor in a newer car is not allowed, the car itself by this time thinks it has a 2.7T. VAG-COM reads 2.7T on it, you can clear codes, check them, log, check emissions, etc. So, when they hook the scanner up, as long as you have everything hooked up on the 2.7T to pass emissions, it will. This is awesome news because I know it can be a huge pain in some states
Now onto the swap....
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How does the motor mount up to the engine mounts?
1.8T: Drops right onto the mounting brackets
3.0: Drops right onto the mounting brackets
4.2: requires 1.8T/3.0 mounting brackets
How does the motor mount up to the trans?
1.8T: Needs B5 S4 trans plate (01E103551C)
3.0: Needs B5 S4 trans plate (this is a 2.7T trans, 01E103551C)
4.2: Needs B5 S4 trans plate (01E103551C)
What transmissions can I use?
- B5 A4 1.8T Quattro/FWD
- B5 A4 2.8 Quattro/FWD
- B5/A6 2.7T (preferred but needs other parts to install)
- B6 A4 1.8T Quattro/FWD
- B6 A4 3.0 (preferred)
- B6 S4 4.2 (preferred)
What clutch do I use?
- B5 S4 clutch/FW
How does the power steering hook up?
- Use an S4/A6 power steering line
Vehicle Speed Sensor (for speedo)
- This has come up before and people seem a bit confused about it. Basically, Audi made the early B6s (2002s) with a vehicle speed sensor in the trans, just like the B5. So, if you have a 2002, just plug it in! For 2003+, the speedo comes from the wheel speed sensor. This is great because nothing has to be done to have a speedo.
5k Rev Limiter Fix - The reason this is needed is because the B5 ECU needs to see speed. If it does not, the ECU goes into "Safe Mode" essentially. You have a few options here:
2002 Cars: You use your normal speed sensor and loop T10 (brown) pin 3 (white/blue) to T10m (black) pin 10 (brown/red)
2003+ Cars equipped with 01A/01E: You can either:
A. Plug in a speed sensor into the port on your trans and loop B5 T10 (brown) pin 3 (white/blue) to B5 T10m (black) pin 10 (brown/red) because T10m is not receiving speed from that sensor
B. Route the white/blue wire shown on page 14 from the footwell to T10 (brown) pin 3 (white/blue). This will solve it as well and you won't need to use the speed sensor on the trans if you do it this way.
2003+ Cars with 0A3 (S4 trans): You do not have a speed sensor on the trans so you need to route the white/blue wire shown on page 14 from the footwell to T10 (brown) pin 3 (white/blue) aka option B above.
Reverse Lights:
1.8T: Plug connector in, also need to connect wiring on the jumper harness
3.0: Plug connector in, also need to connect wiring on the jumper harness
4.2: Need to wire connector in, also need to connect wiring on the jumper harness
Intake
- Has to be custom but honestly not too hard to do. Some people (like myself) just throw a cone filter on and call it a day. Some silicone and a few aluminum pipes could make you something nice.
Exhaust
- The cheapest way to get it running would be SSAC downpipes, mated to a stock S4 catback (which has decent sized piping for stock and can be found from Free.3-$200). Keep in mind this will require some custom welding, but shouldn't cost much.
**SSAC are *NOT* a direct fit nomatter what people say. You could also use B5/C5 trans mounts with the proper subframe. That WILL fit**
A/C
1.8T: Need Compressor - Reciever/Dryer hose
3.0: Plug n' Play
4.2: Need everything - Compressor, Both lines to compressor, Receiver/Dryer, line from Car-Receiver/Dryer.
*NOTE* Compressor Mount (06C 260 835 B) is needed for both 1.8T and 3.0 compressors. Otherwise you will have belt issues since the angle will be slightly off.
Snub Mount
1.8T: 3.0 Snub Bracket
3.0: Bolts right up like factory
4.2: Need to get something welded - EDIT BELOW
***UPDATE*** Huge shoutout to seanf86. He confirmed that a B5 S4/B5 A4 2.8/B5 2.8 Passat (all are the same part number) core support bracket fits up to a 4.2 core support (and probably others) for the snub mount so you can use stock 2.7t snub mount and bracket. C5 A6 bracket will NOT work.
Fueling
1.8T: Need to get 3.0 return line or rig one up. Use 3.0 filter
3.0: Bolts right up like factory
4.2: Need to get 3.0 return line or rig one up. Use 3.0 filter
Radiator
1.8T: Need a 3.0/2.7T radiator
3.0: Bolts right up (need to cap off small port)
4.2: Need 3.0/2.7T radiator/grind some of the core support
SMICs
- Need 2.7T brackets with some drilling/tapping. Could also run Ebay FMIC
Heater Core
- 2.7T hoses fit perfect
Fans
- Ok so this is another thing that can really go a bunch of ways. The 2.7T ECU knows nothing of the fans in the S4/A6, because the 2.7T fan circuit is literally a different harness and module altogether. The B6 chassis use the ECU to control the fans so this becomes a problem.
So, you could:
1. Get the B5 S4 fan module and wire that in
2. Get a universal fan switch and hook that up to the B6 module to trigger the fans. There is a Hayden unit (3647 Adjustable Thermostatic Fan Control) for $35
3. Use the stock fan module on your car and wire it up like a relay using the sensor on the lower fan switch as the trigger. It's already pre-wired for the 2.7T. This is a bit easier on the 4.2 since it has a different module for each fan but it can be done on the 1.8T/3.0.
How to use stock fan module: The factory module is basically a big relay. Just give one of the small wires switched 12V power and use the other as a ground. The lower rad switch completes a circuit so you can use that to your advantage
Also, when you're deleting the mechanical fan, you can get these two pieces (078109123BA + N90216904) to cover up the area where the fan was. JHM sells a piece as well.
Wiring
- So everyone is freaking out about this wiring and it's not easy. Will I help you? Sure. Will I hold your hand and tell you where each wire goes? No. I was making harnesses for these cars but I will not be from January 2019 on. I will be posting all of my wiring online for people to use. Please do your homework first.
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B6 to APB Diagram. ***WARNING: IF YOU DO NOT HAVE A B6 NOR AN APB, THIS WILL NOT WORK FOR YOU.***
This is the diagram I've been making harnesses for the last 6+ years with. Enjoy
B6 to BEL Diagram. ***WARNING: IF YOU DO NOT HAVE A B6 NOR A BEL, THIS WILL NOT WORK FOR YOU.***
B7 to APB Diagram **YOU WILL NEED TO RUN A RELAY TO TRIGGER YOUR FUEL PUMP***
Troubleshooting:
Car doesn't turn over?
If not, DO NOT, I repeat, DO NOT worry about the ECU or anything related. This system is completely divorced from the engine.
Steps to check:
If you have a starting relay in place (recommended):
1. Bypass the relay by putting a large wire in between the main leads. If this works, your clutch switch isn’t grounding the grey/white wire. Fix that
2. Check for 12V switched power on the chassis side Brown plug pin 4 (black/red). If this wire has power, somehow it’s not making its way to the other side of your relay. Fix that
3. Make sure the accessory harness is hooked up (includes ground for the battery and small wire to the starter).
Car doesn't start?
Is the CEL on WHEN THE KEY IS ON ACCESSORY (dash/radio on)?:
If not, your ECU is not getting power. The car uses this as it’s own troubleshooting mechanism
1. APB - for some reason, Orange Plug pin 5 (black/blue) is not getting power. This is the power for the ECU and injectors
2. BEL - for some reason, Orange Plug pin 1 (red/green) is not getting power. This is the power for the ECU and injectors
CEL is on but still won’t start:
Your ECU is blocking the fuel pump (assuming you set it up properly)
Usually this only happens if your crank position sensor is bad
1. Check for codes
2. Log RPM (or look at the tach when cranking). It should be a CONSISTENT 200rpm, not sometimes, and not random values. If it’s not, replace the Crank position sensor. No, I don’t care that it was fine from the car you pulled it from or it was brand new, it’s bad, replace it.
You have no spark:
1. Check your ICMs, they could be backwards
2. APB - Check orange plug pin 1, this is your coils. They should have 12V when the key is on acc. If they do not, fix that.
3. BEL - Check orange plug pin 1, this is your coils. They should have 12V when the key is on acc. If they do not, fix that.
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Please let me know if I've forgotten anything or if you have extra questions and I will add them to the DIY thread
Thanks,
Clint
Reply With Quote
Originally Posted by widgget
.. but luckily for both of us I won't. Thanks for piecing this together.
GONE
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