VW Vortex - Volkswagen Forum banner

DIY How To: Wideband 02 harness conversion for support of Pressure Based Tunes

81K views 87 replies 25 participants last post by  krashot 
#1 ·
Wideband Conversion why?

When moving away from the factory ME7 tune you have options such as flashing the ecu with a fixed 93 octane tune, or go standalone, or move to BT tunes. Some of the quality BT tunes need the feedback from a wideband 02 sensor rather than the narrowband 02. With the feedback from the knock, cam, crank, MAP, with the wideband sensors the tuner is able to create a Pressure based tune that IMO is highly reliable.

Wideband ECU Conversion applies to?
Early generation 225 TTs (AMU) had narrow band 02 sensors and did not have VVT, look at your head, if it's stamped BEA you should see an electrical plug on the right of the head at the cam chain tensioner which will confirm that you have a wideband already in which case you don’t need to read this wideband conversion.
Notice the electrical connector on this Cam Chain Tensioner, if your has this you have a wideband system already.


Required tools-Parts
1. You'll need a VW/Audi connector pin removal tool, you can source these at your local napa / or other parts dealer usually in a round circle tool that has multiple ends on it, or here are some other examples... the small green one on the lower right would be a good example, or in a pinch you can make one out of a pair of tweezers and a grinder




2. Go to a junk yard, get half a wiring harness from a wideband VW GTI / 180HP TT or wideband 225 TT (simply look at the head and if the VVT has an electrical connector it should be a wideband harness). If you source one from a Wideband TT no problem, you can actually swap it right into your car! Don’t forget to also grab the plastic cover from under the car that is used to hold the 02 connectors. If the harness came from a VW the harness will be too short by about 8 inches at the ecu and as such you should not swap it into the car instead you should follow the steps documented below...The pics show the plastic 02 cover from the bottom of the car and shows the 8" problem between the Audi ECU location vs the VW notice how the plug to the ecu is too short on the bottom(VW) harness compared to the top(TT) harness.

Here's the deal, Don't cut the harness, I will always worry that I introduced extra resisitance and in the future anytime I have a wierd issue I will worry it's from my soldering / heat shrink etc.


3. Next go to a dealer or there are a few sites on line and buy some new pins of various sizes, I keep a stock of small med and large pins, without wires and some like the 2nd pic with the yellow wire in them for projects like this. The one you need will be a large pin for the ecu # 115



3. Go to Frys or somewhere get three Resistors, 15 Ohm 25 Watt. One is for the VVT, the other two are in case you want to do a evap delete and your LTF trims don't adapt, you either have to plug the elect back in or try the resistor. (With the Evap delete you don't get a CEL, but your LTFs don't adapt)

4. Source a WideBand motronic ECU and have your tuner place the appropriate BT Mafless tune on it. (VW ECUs will save you a lot of money and work fine, the pic below is generic don’t try to read the numbers)

5. Pick up a wideband 02 sensor, I found autozone to be very cheap for a factory Bosch Wideband ($50 range) I specify a 1.8T GTI 2002

Time to get to Work:
Disclaimer: This process is not for the average person, and I am providing it only so that you will know what worked for me. I am not stating that this is safe for you or your car, use this information at your own risk. You should double check with your tuner before taking any of these steps, you should ensure that the process below will work for your vehicle, you should check your Bentley and ensure that the pin out data / relays etc apply to your vehicle. You should have Voltmeters, shrink wrap, solder, soldering iron, etc and be comfortable with electronics before attempting this process.
(Disconnect your battery and allow the car to sit for 10-30 mins before starting this process)
1. Run a new wire from the new clip that you install in pin 115 of the ecu harness to the resistor, then to relay 100 (you need switched power from a relay) A suggested relay is 100 as it was used for your SAI, which you might have decided to delete, I am pretty sure that you'll want pin 3,. this relay is in the box right next to your plastic wire duct on the right hand side of the car leaving the engine bay to go through the drip tray. You'll notice in this pic where I am relocating relay 100 and the resistor into a 02 cap that I will place on top of the cover under the drip tray. I personally used a different relay for a secondary fuel pump so I could move the box completely, but that was me which is why I am guessing on pin 3.


5. Unwrap the donor harness, take the wires for the wideband 02 sensor along with the connector and the pins from the ecu, write down the color code / pin out on the ecu connector, pull the pins and then insert them into the harness on your car. (You'll have to remove the pins from your current narrowband. (I advise you to double check your Bentley and to read the elec drawings from the Bentley to determine what pins you should use)
On WideBand harness for a BEA Motor G39=Heated Oxygen Sensor ECU Pins=[ 51=grey/white, 70=green, 52=grey/red, 71=black, 5=brown/green]

When you have the car running with the new wideband ecu remember to check your LTF ie adaptation via block 033 the % should be changing
Note 1: for me I found having the tuner kill ESP was a must... with big WHP ESP is just a problem you don't need.
Note 2: If you go with a aftermarket EBC instead of using your N79 be sure to install some sort of boost cut safety. In my case I am reusing one of the evap solenoids and running a signal to it from my water meth computer. If the water meth computer receives an AFR problem message+EGT+RPM+TPS, then it sends a signal to the solenoid to dump my boost and keep me from cooking the motor. Once all is said and done don't worry about the following code when you vag your car... 18058 Powertrain Data Bus: Missing Message from Instrument Cluster P1650 -35-00 Since we are using donor ECUs from VW as they are alot cheaper, this code is always present, but does not cause a CEL, nor any emissions / performance concerns.

 
See less See more
17
#8 ·
FV-QR

I get everything you are saying except why I would need the plastic cover from underneath the car.

Basically you are taking the wires from the donor ecu and transplanting them into the TT wire harness. Is it truely necessary to do that? Couldn't I just add wires of my own and not use a donor wireharness as long as I have the appropriate pins for the harness?


Modified by jwalker1.8 at 7:03 PM 1-24-2010
 
#9 ·
Re: FV-QR (jwalker1.8)

the plastic cover is what I used to protect my resistors, and a relay that I didn't want to leave in the engine bay.
You can add wires, pins, connectors, and resistors without a donor harness.
Things to remember, even with the deletes, and a sep EBC, you still need to have certain items plugged in for electrical connections or try resistors, Basically if these items aren't addressed your LTF trims won't adjust.
N79, EVAP, VVT
Currently I have all the deletes from Uni, and use a resistor for VVT, but still have the N79/evap Electrically plugged in. One day when I have some additonal time I will try resistors for the N79 and Evap
 
#12 ·
FV-QR

Good stuff today. Went to VW dealer here in town and told him I need the o2 connector piece and he found it on ETKA and ordered it for me for $10. He also told me he would pin it out so all I have to do is solder the wires to it and run them to the ecu and I'm done. He also has some pins for the ecu he will give me for $5.
So wideband conversion will cost me
$20 misc pieces from vw
$5 wire
$50 o2 sensor
Wideband ecu traded for my old TB...new TB $20
Grand total for conversion $95 plus my time
Will post up some pics when I start to do this so people can see exactly which pins need to be altered. Waiting for ECU and pieces from VW. Hopefully done within a week!
 
#13 ·
FV-QR

One thing that I am confused on is the difference between this write and another write up I had read.
This thread says
EDIT THIS PIN OUT IS FOR BEA
G39=Heated Oxygen Sensor ECU Pins=[ 51=grey/white, 70=green, 52=grey/red, 71=black, 5=brown/green]
Whereas the other says
EDIT THIS PIN OUT IS FOR AWP
Six wire (1-green, 2-black, 3-blue/red, 4-white, 5-grey/white, 6-grey/red) connector.
Heated O2 before the cat
Pin 5 - ECM 51
Pin 3 - ECM 66
Pin 1 - ECM 70
Pin 6 - ECM 52
Pin 4 - ECM 5
Pin 2 - ECM 71

Differnce being this thread says something about G39 = heated oxygen sensor
Other thread has pin 3 going to ECM 66.
Detailed Pics to come including taking apart harness and wiring/heatshrinking


Modified by jwalker1.8 at 8:15 PM 1-25-2010
 
#14 ·
Re: FV-QR (jwalker1.8)

Your going to have to check it out at a junk yard or get someone else to chime in. in my case I replaced that side of the harness with a donor so I didn't have to worry about it. If I did it again, I'd do exactly what your doing. Unfortunately, the data...
On WideBand harness for a BEA Motor G39=Heated Oxygen Sensor ECU Pins=[ 51=grey/white, 70=green, 52=grey/red, 71=black, 5=brown/green]
Is from my bently and it shows the same data for both the AMU and the BEA, so it can't be right.
Be sure and post up once you have the final data and I'll edit the original with the updated info. Thanks
 
#15 ·
FV-QR

Ok here is the dilemma I am having. The pic is from my Bentley for engine codes ATC, AWP, AMU.
The highlighted "G39" indicates the O2 sensor. where it says "T6q" and then a number represents the 6pin connector. and the number after the dash of "T6q" represents the corresponding pin to the O2 connector. For example "T6q/5" means that particular wire goes to pin number 5 of the connector.
The one that is highlighted T6q/3 that comes straight down off od G39 is going to something that says "54". This is not ECM pin 54. I am not sure what it is. The circled "D80" is "plus connection (87a-for evap system solenoid) in engine compartment wiring harness.
Can anyone help me out here?
Where user VRT said ECM 66 goes to pin3, I have highlighted ECM "66" and "J299". J299 is secondary air injection pump relay.
I am just confused about pin 3 and where that is going for sure.


 
#16 ·
Re: DIY How To: Wideband 02 harness conversion for support of Pressure Based Tunes (2001TTransport)

Here is my version
First off I am not responsible for anything you do to your car or anyone elses. This type of work is done at your own risk.
Ok, I decided to make a collaboration of a few different DIY threads and advice I got along the way and make one final easy DIY thread.
Things needed
Wideband ECU
Solder (60/40) & soldering iron
New o2 harness
Wideband o2 sensor
wire & wire cutters
heat shrink tubing
15ohm 25 watt resistor and ECU pin
picks and various other tools such as a 7/8 wrench for the o2 sensors
First you will need your new o2 harness. You can order these from a VW or Audi dealer. Part number 1J0-973-733 If you are cool to the guy working he will probably put the pins in for you and you will end up with something like the pic below and cost around $15. You will also need another pin that you will have to insert into your ecu harness for VVT (pin 115). For this I suggest taking your ecu to the dealer with you and ask them for the correct size pin just to make sure.
Your new o2 harness 1J0-973-733

Your new pin for VVT (ecu pin#115)

Now with your newly acquired pin and harness in hand locate the existing o2 harness. You will see 4 wires coming from that which are conveniently all used in your new harness.
Existing 4 pin o2 harness

From here get your soldering iron plugged in and make sure to have shrink tubing and a heat gun to re-insulate your wires.
Your new wires will go as such
Existing harness New harness
Pin#1 goes to Pin#3
Pin#2 goes to Pin#4
Pin#3 goes to Pin#5
Pin#4 goes to Pin#1
(wire colors vary from some years and ecu but the pin out remains the same from the research I have done)
Now you will have two wires left for your new o2 harness. You will then need to run the two new wires from the ecu harness. I used 22gauge strand wire and 60/40 solder.
Pin 52 on ecu harness goes to Pin#6 on your new harness (there are two harnesses to the ecu, you need the larger side harness)

Pin 71 on ecu harness goes to Pin#2 (same harness directly above pin 52)

To disassemble your ecu harness look for the purple clips on either side.


Use your pick and pull the clips out.


Then pull the rubber orange seal out

From here look for the tabs on back of the harness and pull the back off

Now you will see another purple clip, pull that straight out.

From here, gently pull out the two wire harnesses and add in your new wires (pins are there already and if you look very closely you can see tabs that will bend over and hold the wire in place. (no soldering necessary here, enter wires in through the orange seal)

Once you have your two new wires in and soldered into place, reassemble the ecu harness and move on to the VVT resistor.
The resistor I used was a 15ohm, 25 watt resistor

Now for the VVT you will use the other smaller ecu harness and pin 115 shown here

This side disassembles the same way as the other with the purple pins. Once disassembled, you will use your pic and push a small rubber grommet that is lodged into the pin 115 spot out and proceed to insert you new pin into this spot. It should "click" into place when it is in the correct orientation.

Use your pick and make a hole in the rubber grommet so you can thread your new wire in threw it.



Soldered one end to the wire from pin 115 you added and the other end into the evap solenoid at pin#1 of the evap's solenoid.

Once you have all this done, clean everything up, zip tie your wires out of the way of anything hot, I relocated my evap solenoid under my rain tray and wrapped all the wires together with electric tape and plastic tubing for a clean look. Now you can plug in your new o2 sensor and ecu and enjoy your new MAfless file.
If there is anything in particular you would like a pic of just ask and I will see what I can do. As for pics of actual soldering, well I figure if you can not handle soldering on your own you should not be attempting this to start. Good luck and enjoy.
 
#17 ·
Re: DIY How To: Wideband 02 harness conversion for support of Pressure Based Tunes (jwalker1.8)

nice work both of you. So can I send my harness to you guys with a case of beer? pretty pls

I have done some of the electrical wiring for gauges and stuff but a bit skured doing something like you had described, never soldered before so rather have someone do it that has done it before
I am sure we can work out an ample compensation.
 
#18 ·
Re: DIY How To: Wideband 02 harness conversion for support of Pressure Based Tunes (chaugner)

Quote, originally posted by chaugner »
nice work both of you. So can I send my harness to you guys with a case of beer? pretty pls

I have done some of the electrical wiring for gauges and stuff but a bit skured doing something like you had described, never soldered before so rather have someone do it that has done it before
I am sure we can work out an ample compensation.

Well, if you go the route I did you won't be removing the wire harness from the car. It's actually really easy. Just 7 wires total to solder and done.
 
#19 ·
Re: DIY How To: Wideband 02 harness conversion for support of Pressure Based Tunes (jwalker1.8)

Quote, originally posted by jwalker1.8 »

Well, if you go the route I did you won't be removing the wire harness from the car. It's actually really easy. Just 7 wires total to solder and done.

2nd, after I had completed mine I stated that if I were to have done it again, I would have simply added the wires, which is not a lot of work. watch some Youtube on soldering and you'll be fine. Just make sure you don't use acid core
 
#20 ·
FV-QR

Just a little clarification, UNI or Eurodyne deletes ONLY delete check engine lights...NOT that actual cause of the CEL. Meaning, even though you delete something you still need to fix it.
Example: If you have Eurodyne delete you VVT, you still need a resistor in there if your car does not have variable valve timing. If you do not your fuel trims will not adapt.


Modified by jwalker1.8 at 10:31 AM 2-8-2010
 
#22 ·
Re: DIY How To: Wideband 02 harness conversion for support of Pressure Based Tunes (2001TTransport)

I have just completed the process off doing this conversion on my 2001 Audi TT 225 AMU and it all worked out very well, except now I have one lingering DTC:
17862 - Exhaust Gas Temp Sensor 1 (G235): Short to Ground
P1454 - 35-00 - -
I can't help but wonder if it related to the ECU swap. In fact I'm not even sure if my car has an EGT sensor.
Anyone have any ideas?
 
#24 ·
Re: FV-QR (jwalker1.8)

I put in an 06A 906 032 NK that has now been rewritten to 8N0 906 018 BB. I did not swap the entire harness, just added two wires and re-pinned the original wires into the new wideband plug.
The reason I am confused is the Bentley wiring diagram clearly shows that the AMU has a G235 (EGT Sensor), but I can't find it on the car and I seriously doubt it's there.
 
#26 ·
Re: FV-QR (jwalker1.8)

Quote, originally posted by jwalker1.8 »
Which page in the manual are you reading this? Are you sure there are no asterisk ** next to the diagram?

That's the funny part, if the AMU doesn't have an EGT then it is a blatant misprint in the manual. For the 2001 Audi TT under the section with the Motronic ECM no. 2/6 there is clearly a G235 with two asterisks above it and then on the right margin next to the two asterisks it says "- only engine code AMU"
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top