Dual O2 sensors to single, how?

[Lari Temmes 0]

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 March 23, 2019 by Lari Temmes

[RBPE 198]

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 April 2, 2019 by RBPE

[Lari Temmes 0]

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.

 

 

[RBPE 198]

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;

 

 

 

[Lari Temmes 0]

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 April 20, 2019 by Lari Temmes
added links

[Lari Temmes 0]

Additional question. Can i test run this in open loop state? All components are stock, so it should be ok?

 

[RBPE 198]

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. 

[Lari Temmes 0]

On 22.4.2019 at 1:28 PM, RBPE said:

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. 

 

Right, after testing this and that i decided to use both upstream o2 sensors. It's was actually pretty easy to put them onto my chinese exhaust manifold, just like they are on HPA exhaust manifold. That solved my o2 issue and fuel trims seem fine now and i don't get error codes.

 

It actually runs pretty well with stock ECU. On WOT and >3500 rpm it pushes 0.6bars just fine  Tried with ethanol too (50%-50%) but it was too much for stock ECU.

 

 

 

 

 

[RBPE 198]

On 5/11/2019 at 8:04 AM, Lari Temmes said:

 

Right, after testing this and that i decided to use both upstream o2 sensors. It's was actually pretty easy to put them onto my chinese exhaust manifold, just like they are on HPA exhaust manifold. That solved my o2 issue and fuel trims seem fine now and i don't get error codes.

 

It actually runs pretty well with stock ECU. On WOT and >3500 rpm it pushes 0.6bars just fine  Tried with ethanol too (50%-50%) but it was too much for stock ECU.

 

 

 

 

 

 

Making 02 bungs in a cast mani is generally the way many do it, emulates the big name tunes. The two ways are generally like those, manipulating the air modelling whilst taking into account the P/I portions required to a degree (rl/rpm/egt/evap/vvt etc) and forcing open loop, or alternatively running it like oem on closed/open loop and taking into account the PID, adding either simple custom PID routines or more detailed patches and heavily modding the electronics to suit - both quite difficult in their own ways.

 

The ignition (KFZW) on these isn't too bad at low load/rpm, prob need to bump it up a touch around idle and low rpms (>2k rpm) similar to 2500-3500rpms range but slightly higher values (42-45 at low rpms/load, >50 ish at high rpm/low load), then bump the high load up throughout the rpms and a mix of higher values in the mid range. If you look at the various SU/LEV types of monitoring (ME7/ME9/MED9 for example dep on your car), they'll give you an idea of what areas you need to think about as well as air mass modelling for post ambient on a none map car if you're not hacking the ecu and can bus to bits!

 

WB02 FTW also so use those gauges to keep an eye on the afr's!

Edited May 17, 2019 by RBPE

[Lari Temmes 0]

On 11.5.2019 at 4:08 PM, RBPE said:

The ignition (KFZW) on these isn't too bad at low load/rpm, prob need to bump it up a touch around idle and low rpms (>2k rpm) similar to 2500-3500rpms range but slightly higher values (42-45 at low rpms/load, >50 ish at high rpm/low load), then bump the high load up throughout the rpms and a mix of higher values in the mid range. If you look at the various SU/LEV types of monitoring (ME7/ME9/MED9 for example dep on your car), they'll give you an idea of what areas you need to think about as well as air mass modelling for post ambient on a none map car if you're not hacking the ecu and can bus to bits!

 

WB02 FTW also so use those gauges to keep an eye on the afr's!

 

Do you mean these are modifications are that are generally made, or that i would need to do these to make use of ethanol fuel? 

 

 

[Kompiesto 0]

Hi, I worked on my R30T firstly with my friend RBPE and now, i know more about ME7 and modify my setup by yourself using assambler coding. 
I created solution to modify internals of ecu with some map changes, as RBPE shows, but all dont work as i want. Problem is with sampling of WBO measurments by MCU. ADC channels are multiplexed with some delay and WBO measurments can move after few minutes of idling. Only good solution is modify MCU code to use BANK 1 corrections of fuel to both banks. I done this but is hard to do.

You can run open loop, its simple. Disconnect WBO lambda sensors. Fr_w will 0% all time. If You delete diagnosis WBO sensor by CDLSV, LSHV, ECU will be thinking thats WBO working normaly, Fr_w will by flying because ADC will be see some voltage, without WBO connected. This can damage your engine. I saw this on my car.

Full open loop in my opinion is very dangerus.

[RBPE 198]

On 5/18/2019 at 7:35 AM, Lari Temmes said:

 

Do you mean these are modifications are that are generally made, or that i would need to do these to make use of ethanol fuel? 

 

 

 

Yes, generally made with lots of other mods as well just for normal fuel, na to fi is about the hardest thing you can do on Motronic, either on a flash based tune or the mods needed inc. custom coding and parts. There are a few ways you can go about it, best bet is to learn the basics on the Function Sheets online, things like BGSRM, BGRLP, BGAGR etc which can all have an influence on the relative charge, load, rpm's etc which is what you need to do. I've put up plenty of links to the various aspects but it can get quite complicated and depends on what you can do and how you go about it. I'll try and put up a basic overview to help those going through the 2000 page docs!

 

 

 

Edited October 20, 2019 by RBPE

[Lari Temmes 0]

I'm on a train and bored. So i add my experience here. 

 

Like i told before, i added turbo (and intercooler) to my VR6 3.2 Cayenne and it was good, and it was bad.

 

Good stuff : ME7.1.1 can handle it very well and stays in closed loop mode (with stock WBO2 sensors fitted to exhausta). No codes (expect warning code for MAF "Sudden rush of air"), fuel trims can keep up, very good for normal driving giving more snappier drive experience on low speeds. 

 

Bad stuff : On high RPM (something around >5k) MAF starts to clip, still goes fine because WBO2 sensors can handle it.

 

Deadly stuff : Failing or slow O2 sensor will kill your engine. Hitting RPM limiter will kill your engine. Failing knock sensor will kill your engine. I killed my engine. 

 

Currently rebuilding my engine. Pieces of piston could be found from oil pan. Piston was fine on top, but cracked on side between two piston rings.

 

Stock fuel, i would not go over 0.5 bars. I think with engine working perfectly before adding boost to it, there should be no problems.

 

I'm going for E85 fuel and bigger injectors for my next try. Knock sensor and O2 sensors are also fixed. Engine still sits outside car, but week or two and it will be running again

 

 

 

 

 

 

[RBPE 198]

You need to make about 2-300 changes in the ecu to have them running right without boost sensor, not an easy job!

 

You need to do ignition, fuel (oem injectors pretty small for any boost but you can do all the 3/4 bar changes, return/returnless etc), fuel mass, flight time mani dep, throttle angle, air mass, torque, exh temp modelling.... list goes on and that doesn't include the set up/ecu configuration changes depending on what parts you're using - oh and dsg if your using that.