anyone scaled the analog narrow band output on a mtx-l so one sensor can do both wideband and supply the ecu with narrow band?

I know I would need a resistor to fool the heater element too

 

I cant believe I'm the first to do this ?!?

 

I hope my post don't take you question off topic. I have been thinking of installing an AFR gauge to make sure the Mini does not run too lean on tracks. My only mod is 15% pulley and no tune. From all the threads I read I should be fine, but I don't know it that include a lot WOT on track.

I don't want to go thru all the trouble if I know my car would just be fine on track without bigger injectors. And yes, I read countless injector threads too. It seems there are very few has installed an AFR gauge in their mod'ed Mini. If I do I plan to weld a dedicated bung for the WB sensor. What cross my mind too is I would double check the header to be sure there is a good place for the new bung and the WB sensor, before buying a gauge.

For me, I would not want to try to share the WB as NB for the DME - to save welding on a new bung. I think scaling with a resistor network must have down sides.

 

OK. I looked into the MTX-L a bit more and now I see what you try to do. Have you find the Mini's DME's O2 sensor output characteristic?

Here is MTX-L yellow wire output voltage vs AFR.

I have read Bosch's O2 sensor literatures and they are typically clear as mud and give just a crappy graph not intend to be used quantitatively. Have you try asking Innovate support guys? They might be able to help.

 

Mtl has two outputs one for the gauge and one that can be configured as the stock narrow band, I never tried it. If I were you I would guy the first cat at the same time, nice almost free hp bump

 

I have been misled by Innovate's lousy pdf documentation. Only with deeper dive that I found the brown wire and more digging the NB emulation. They do not hype the narrow band emulation which led me to suspect it is a use it at your own risk. I have since read up more on various forums to the successes and failures of folks tried to substitute the stock narrow band.

I think we think the same of wanting to use the pre-cat O2 bung instead of welding in a dedicated new bung. The latter is likely easier said than done knowing the packaging challenges of the Mini. You want to weld in the bung between 9 and 2 o'**** and reality may make that impossible but I have not check.

So did you ever install the MTX-L? If not you, and soon me, just joint the long list of prolific posters on the mega injector threads that said it is a no-brainer to get a WB sensor instead of guesswork.

I am very apprehensive as I don't want to install the MTX-L with the NB emulation and only to screw up the pre-cat O2 signaling to the DME. I would prefer to leave the factor 02 sensor alone if I can help it, to avoid reading garbage-in, garbage-out that I screw up the DME F/A ratio.

 

yeah I've been using mine, it's damn near worthless on the track, every time you lift the afr goes red, so I pretty much ignore it now.

But if the car loses power it'll be right there next to the boost gauge for a quick glance

 

I have done this and been running fine for the past 5months, I tapped into the primary o2 signal wire and am using the MTX-L for narrowband simulation. You also need to simulate the stock o2 heater so that your ECU maintains adaptations correctly, this is the resistor I used (http://bit.ly/2uhElXq). You will also need to reprogram the voltage ranges for the MTX-L, I am running the range of 0.05v - 0.95v and left the factory AFR data.

I am also running the Bytetronik FA53 so my car is tuned and setup properly for all of these changes.

*also make sure you mount the resistor somewhere you won't light the car on fire, it will get hot and melt plastic.*

 

Thanks for all that shared your experience. Only when my stock header failed this past Friday that I made a point to see the challenges of fitting an additional bung for the WB gauge. It doesn't look easy - as anything on our little car.

While I like the idea of using the MTX-L analog output to emulate the narrow band pre-cat O2 sensor I have my reservation. That is how to ensure the emulation is close enough to the factory sensor characteristic (i.e. Lambda vs voltage). It would defeat the purpose if by installing the MTX-L only to bastardize the DME's fuel trim feedback loop.

My thought is may be the factory O2 sensor tolerances are very sloppy so you have to be grossly way off to screw something up. I would rather err on the side of caution in the absence of compelling evidence.

I welcome anyone who would share their experience and knowledge.

 

I am planning to install a MTX-L Plus wide band and use the NB emulation output. Will someone please donate your bad O2 sensor? I will reuse the harness and connector to connect to the upstream harness. I will pay shipping.

 

My endeavour to the trouble of installing a wideband gauge is to see it for myself the A/F ratio at high WOT duty cycle on track, of the bone stock 330cc injectors, with bone stock ECU and 15% SC pulley. I have done copious search and reading dating back to the early days of R53 to no avail. There are many opinions from the prolific injector size posters but non that I can tell from putting their cars on tracks.

I acquired a set of JCW 380cc but I would like to know the change with each step of modifications that I do to the Mini. I will share what I find to all to see.

I actually plan not to install the gauge. It is one of those things that you only need to know the data once, and after that the gauge is just another nuisance, as well as the challenge to find a place to house it.

 

I am still looking for a donation of an expired O2 sensor. Thanks

 

Thanks to Zsm, an expired but not so departed O2 sensor is on the way. Still need to buy the MTX-L Plus and find a home for it in the jam-packed Mini interior.

 

Thanks to Zsm, this expired O2 sensor arrives from San Francisco. I will reuse the pigtail harness and connector so no need to butcher up the Mini's upstream O2 harness.



astroblack53 sent me the link for the power resistor that I need to buy to fake the heater in the O2 sensor. I just need to open the wallet for it and the MTX-L Plus gauge. The biggest challenge for this project is to find a home for the gauge.

 

Bringing this thread back to top. I have just read the Bentley Manual about the O2 sensor heater operation. Did you first try without the resistor to fake the heater first? If so were you getting fault codes?

I know that the O2 sensor heater is a closed loop operation (per what I infer from reading Bentley) so I would expect even if you fake the heater with a resistor the ECU may be unhappy because the narrow band emulation will not have the effect when the ECU turns on and off the heater.

Contrarily I suspect that the ECU may not know if the heater is not there, unless the engineer wanted the ECU to know if should the heating element goes kaputt. I am just trying to think through the issues.

Ideally, the best implementation is just to add another bung for the MTX-L gauge and keep the stock upstream O2. With the stock header it is close to impossible unless you are willing to risk putting the wideband sensor at a compromised orientation - potentially risking killing it frequently from condensation of water and whatever combustion byproducts.

 

I did initially try to run without the resistor and I had disabled the heater options, while the car ran and did not throw any codes, however it also was always running in Open Loop and thus daily driving wasn't super optimal and ECU adaptations were not learning.

 

Thanks so much. This is really useful. It suggests that the ECU indeed monitors the current supplying to the heater. Open loop is definitely not something you want to do except for WOT.

My preference to keep the stock upstream narrow band is MTX-L's narrow band emulation will not have the causality of the ECU turning on and off the heater. It should, however, have a good emulation when the ECU thinks that the O2 sensor is hot enough. What still trouble me is how often the ECU turns on the heater. A lot to think about. It would be nice if it is not so difficult to add another bung at the angular range per the O2 sensor installation instruction.

 

Any update on this? Did you ever work out a way to do this with a resistor? My other thought, and a lot less sexy would be to just keep the old o2 plugged in (away from things that could melt) and tap into the o2 0-1v line with the MTX.

 

ECU does check that there is resistance in the heater circuit. If it doesn't see resistance it'll throw a fault code because it thinks the heater circuit is broken. It's an emissions thing; heating up the sensor gets it to closed loop operation faster. Sensor heating is active for a short period every time ignition is turned on.


I've heard ppl do exactly that to avoid adding a resistor. It should work just fine.