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Lari Temmes

Dual O2 sensors to single, how?

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Hello everyone, my first post. I have little project with my Porsche Cayenne that has Porsche rebranded VR6 3.2 24V and would appreciate some help and ideas.

 

My plan is to turbo it. It's 250hp stock and i'm simply going to stick eBay turbo on it and keep it stock as possible. Stock intake, exhaust, injectors, MAF, fuel pump etc. I did some simple calculations and stock components (like injectors) should be good for around 80-90 additional horses and 6-8psi. ECU is ME7.1.1 022906032T btw.

 

Anyway, since i'm going to start with stock ECU (don't judge me just yet, i have my reasons) first issue comes with exhaust manifold and downpipe that only can support one "bank" and the fact that there are separate o2 sensors for bank 1 and bank 2. So, total of 4 o2 sensors and two of them are wideband. ECU adjusts fuel trims for both banks.

 

So my actual question is, how can i overcome this problem that i can only measure one bank, instead of two. (With bi-turbo there wouldn't be such issue ... :)

 

I have few solutions in mind :

 

- I stick both upper o2 sensors to exhaust manifold before turbo. Exhaust gasses are somewhat mixed in manifold, but if positioned correctly, bank1 and bank2 should still respond differently somewhat.. or maybe not? They would be before turbo in this case.

- I stick bank1 upper o2 sensor right after turbo, and split electrical signal coming from it to both upper o2 sensor pins on ECU. ECU would see identical lamba value for both banks.

- Some other electronic trickery?

- Ecu reprogramming? I would need some help with this, i don't know how to make it use single o2 sensor only. Plenty of information how to remap it and such, but i can't find any information about this.

 

My downpipe will have catalytic converter, so lower o2 sensors really won't be a huge problem, i thinks i can simply fit them both there without any signal splitting or other tweaks.

 

* by upper, i mean o2 sensor that is located before cat, by lower, i mean o2 sensor that is located after cat. In my case, upper o2 sensors are wideband, lower are narrowband.

 

.. why would i wan't to turbo my slow Cayenne SUV? I have two of them and this second one is something i wan't to turn into a monster and fitting it with lowboost turbo is just one part of it. Poor Porsche is already old and abused, i'm not messing up with any piece of art car.

 

Thanks.

 

Edited by Lari Temmes

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Dual 02 mani like HGP/HPA or single 02 conversion.

 

I had Kompiesto draught me a quick guide for the DIY folks (thanks Marcin), which you can find here;

 

https://app.box.com/file/302875520967

 

EDIT - There's a 2-1 and 1-2 split on which bank of cylinders read which on the dual route, best to get that right if you go down that route

Edited by RBPE

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On 2.4.2019 at 4:25 PM, RBPE said:

Dual 02 mani like HGP/HPA or single 02 conversion.

 

I had Kompiesto draught me a quick guide for the DIY folks (thanks Marcin), which you can find here;

 

https://app.box.com/file/302875520967

 

EDIT - There's a 2-1 and 1-2 split on which bank of cylinders read which on the dual route, best to get that right if you go down that route

 

Thanks. Can't get to that guide, but yes. Dual O2 manifold is option. However, i'm going to try splitted o2 sense signal first. See how that goes.

 

 

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On 4/16/2019 at 3:56 PM, Lari Temmes said:

 

Thanks. Can't get to that guide, but yes. Dual O2 manifold is option. However, i'm going to try splitted o2 sense signal first. See how that goes.

 

 

 

Not sure why that's playing up? Screenshot it for you anyway;

 

wbo1

 

wbo single 2

 

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Thank! That is very interesting. I already tried to split signal from one o2 sensor to both inputs. I had 'some' success, but got 'Lambda sensors exchanged' codes and it just didn't work.

 

Modification to ECU that is descripted here does pretty much the same thing and since input vary a little, there is still -25/+25 issue like stated in documentation. 

 

So, i quess only option to use single O2 sensor (or both sensors in same pipe) is to make software modifications. There are some information about this for commonly used VR6 ECUs, but since this is Porsche Cayenne, there are no information about this specific firmware. I quess i'm skilled enough to make some bit-modification to specified location, but that's pretty much it. 

 

First spin 

https://www.youtube.com/watch?v=e3uKDR5Q-yo

 

Very good study material about wideband o2 sensors and o2 sensors overall :

https://www.youtube.com/watch?v=aPtY5FiGMAE

 

 

 

Edited by Lari Temmes
added links

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CDLSHV - Codeword diagnosis Lambda probe exchange detection

 

Cayenne's pretty much identical in this respect from what I remember, 100+ maps/functions for the 02, most testers/diagnostics and some aging/heating and limits etc, it's all Bosch ME. You need a good def file, makes it a lot easier and there are some on the Net for these Porsche's, ecuconnections has some but you'll need to make some posts to see them I think. 

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