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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.

 
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#84 ·
Anyone else not getting any coolant temp readings after a swap? My dash pod is still in the mail but the climate control says -60 all the time..

Alec
 
#85 · (Edited)
is mine vvt?

So i bought an 02 AUDI TT convertible AMU motor... Missing only the head... No biggie, i bought another AMU swap which I'm about to install, ( just gotta finish putting the new timing belt, water pump, etc. Etc.) Having an extra bottom block, that's attached to the car, i decided to go to the junk yard today in search of a head.. I only found 1.. An AWV, (which i had no idea even existed) off of a 04 VW BEETLE.) In great conditions, bought it for $90, took me a minute to take off, i never worked on a bettle before and found it a bit awkward at first. I finally noticed at home the vvt solenoid on the side of the head and i noticed my AMU motor doesn't either, stumbled upon this thread and now i wanna do this, Can i use the AWV ecu?
 
#86 ·
Wideband conversion MK4 - anybody got one?

Anyone out here that has a wideband conversion kit on hand?
Ordered one from Reflect Tuning for $90; got order confirmation and tracking. A week later, no product and tracking turns out to be fake, no USPS scans.
No answers to email on company website, company facebook page, direct email.
Just another fly by night company it appears.

Now scrambling with project; Unitronics version is 2 weeks delivery.

https://d2isyty7gbnm74.cloudfront.n...d74aebad550453a236cfaaa24f5aa3b/original.jpeg

Straightforward conversion for Mk4 narrowband to wideband ECU with wideband sensor (in this case, ECU is 032 HF from a Jetta).

Shipping to MI 48114 (or pickup in that area if local).
 
#88 ·
Sorry for replying an old thread.

Can someone assist me with the wideband installation? I have AUM engine (swapped from AJQ) I got AUM ECU but I think wiring is narrowband, do I need just to wire the lambda wires? No resistors and stuff? Can anyone assist me? My car runs like ****e currently!
 
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