NefMoto

Sorry if this isn't the correct sub-forum for this, but I'm not asking for a tune per-se.

I'm wondering if anyone has written code to enable wideband O2 closed loop control for the 551M, and if so, if they'd be willing to sell a tune with the code for personal use.

I don't think anyone has done this, definitely not in public file; the narrow band set up works well enough, unless you're looking to do speed/density or flex fuel

I am planing to do something similar over winter, but something real simple. Maybe only PI controler
Also I consider option to convert ASN 3.0 ECU to turbo beacuse it already have wideband control. I will take eqsyer option

That's what I figured, but I thought I would ask. I implemented wideband O2 control in M4.4 by running a wideband's analog output to the rear O2 channel input. This signal emulated the narrowband, placing either .11V or .86V directly into the relevant RAM address right after the original rear O2 ADC. The decision to use .11V or .86V was based on a 16x16 lookup table with axes of RPM and load. The factory PI (no D factor in factory tune) maps were changed to work based on deviation of actual vs measured AFR, so that the speed of regulation was directly related to absolute deviation of AFR vs the target.

I haven't spent much time with disassembly in regards to ME7, but it looks like I'll have to get cracking! The target lambda lookup will be easier than on M4.4, as I can just use lamsbg_w.

If you've already done this once, including PI, you can definitely do it in ME7, but there is no existing lambda control PI code that i think is vaguely reusable in ME7.1.  Maybe you can steal code from ME7.5

Bets of luck. Bonus points if you publish :)

If you want we can do it together(here). On ME7 is not that hard
If my plan is right, only playing with fr_w will do all yob for fuel.
We only need to make PI that will add or subbstract to fr_w based on how far is actual lambda from desired

Actual lambda is easy part, on rear 02 there is a 0-5V input.
And controler have linear output 0-5V, it is easy to convert in ECU voltage to actual lambda

Force fuel trim on even if lamsbg_w != 1.
Then create a mapping of wideband to narrowband based on current request.
Disable the protection that cuts load if narrowband shows lean on boost.

I think that's all that is needed, ECU should do the rest.

whoa fantastic. Thanks prj.

Well obviously you will need to handle the diags and heater diags.
And if you're using external controller, and it goes tits up and sends a fixed signal all the time, then that might not end so well.
Sensor degradation is also a problem.

So in the end IDK if that's such a good idea.
If you look at most aftermarket ECU's with wideband, none of them run closed loop on WOT, because the diagnostics just aren't there to deal with sensor shenanigans.
I certainly would not run it like that on my setup, too dangerous IMO.

Thanks prj. Again food for thought.

You could also severely restrict the correction range while WOT (or other "dangerous" load regions) but at that point I guess why bother.

Every wideband Bosch 1.8T or etc file does this. Wideband controller is disabled when certain conditions are met, too hot, BTS on etc because you dont want a faulty sensor to burn down your engine I guess.

Could put the same conditions or some of them, say if bts=1 , disable correction.

BTS on does not always disable correction. But it depends on how it is configured.
Correction is always disabled when setpoint goes below LALIUSMN.

I have set up wideband lambda regulation for all engine loads, including WOT, for over 200 customers. I know for a fact that it has saved numerous engines from running lean at WOT. I do not know of a single engine that has been hurt by a faulty sensor. I have an error handling routine that will put the ECU into limp mode and  trigger a P0130 DTC when a constant signal is detected for more than 45 seconds. I have seen a few sensors fail and give an erratic reading, but most of the time their failure results in a constant output. I have found that leaning cruise and idle AFRs to around 15.3 increases fuel economy by a few %, not huge, but a nice bonus.

You guys are funny, it seems like the majority of you think that baboons are driving these cars - that a driver has no ability to detect if their is a problem with their engine. I understand advanced engine management systems have the error handling ability to decrease the possibility of engine damage to almost nill, and that you like to keep that functionality at whatever cost. However, from an automotive enthusiasts perspective, being in tune with a vehicle and knowing when something is wrong is part of the experience. For wideband control I consider it mandatory to have a wideband gauge that is easily visible, and to look at it from time to time - it is quite easy to figure out when the sensor is reading incorrectly.

With all that said, I'm not even sure how necessary wideband control is and how good ME7.1's AFR control is at WOT. I have barely started to scratch the surface with ME7. In M4.4 every lambda and VE map, including FKKVS is all in one single map, KFLF. Getting a repeatable and stable AFR at WOT open loop is an exercise in frustration, so wideband lambda control at WOT is very useful.

I am installing dual widebands on my 2.7t this week and will start logging their output through the rear O2 inputs. If I find that a closed loop wideband control routine would be helpful, then I will post my progress towards that goal here.

cool story bro :D

Cool story bro, should have started with M2.3 LOL

The fact that you can't get steady lambda at WOT without closed loop is testament to lack of tuning ability and not anything to do with the ECU.
Even M2.3 had perfect AFR at WOT whether with MAF or speed density mode that I wrote for it, and that was made in the 80s.

You should read what I wrote before so quickly assuming that I don't know what I'm doing. I said getting a stable AFR at WOT is 'an exercise in frustration', not that I can't do it. Changes in lambda in M4.4 can't always be traced in KFLF, as instabilities in AFR don't always follow RPM vs Load, so changes instead have to made to MLHFM - this is of course after a properly calibrated FGAT0 (KRKTE equiv) and TVUB and after tuning KFABAK, KFAVAK, KFBAKL, KFBAW, KFVAKL, KFVAW, KLWF (wall film model). With adequate logging and iterative modifications to MLHFM and KFLF I can get stable and repeatable AFRs at WOT, it just takes a lot of work. For remote tuning customers with novel setups, it's not practical to get this amount of information.

One real world example for why wideband regulation at WOT is helpful - a lack of manifold reference to the FPR. I've seen multiple customer cars that have had the vacuum line pop off their FPR, but the change in fuel delivery wasn't enough to set a P0171/P0172 code. At WOT their AFR would have leaned out, but the wideband routine kept it in check.

It is pretty good and generally works just fine.