Lambda closed loop control x 3

[20B]

So finally last night I switched on the Lambda closed loop control for my 20B rotary engine after playing with the mixtures and idle valve for several months now, I was happy with the idle mixtures before but after running the closed loop they are simply perfect now.
Almost a straight Lambda trace line with it only ever deviating 0.01 either way, very happy
What a difference this makes just to smooth everything out nicely and take control of any little adjustments. Many thanks to forum user Martin who showed me how to data log the channels to work out Lambda delays and then setup the settings to control it, one more reason Motec is worth the extra money and effort !
My question is now that I have 2 lambda sensors controlling rotor 1 and rotor 2 individually with closed loop can I control rotor 3 via closed loop when I purchase a LTC ?
This would be a perfect setup rather than having a 'dumb' lambda sensor that cant make any fuel corrections while the other two can.
Does Motec plan to control more than 2 lambda sensors via closed loop in the future ? Will these be a software or hardware restriction ?
ECU is M800.
Thanks

[Martin]

Im glad i could give some advice ...and that it was actually worth something

Interesting Q on the 3 closed loop channels....the M800 only does 2. Why not run a single closed loop channel, let it only use La1 for closed loop. Then put La1 in the collector and put La2 in different rotors and over time map all the diffrences out with individual fueling for each rotor. This will be time consuming, but you can get it good.

If you have drive by wire, use a multi pos switch to trim for throttle positions, and go to a highway with welding gloves and a 22
La1 measures overall fueling.
La2 rotor1...100% sweep of rpm range, then 80% sweep of rpm range, then 60% etc etc etc..
Stop and put La2 on Rotor 2...do all the sweeps again.
Repeat for rotor3

If you go back home and pull the logging of the whole lot you will have some good info! just dont do the sweeps in top gear since you might get yourself into trouble with that, keep the speeds legal


btw...at what speed do they they take your keys?

[robespierre]

Show to data log the channels to work out Lambda delays and then setup the settings to control it, one more reason Motec is worth the extra money and effort !

Do you mind sharing here on how you did the above?

[20B]

Do you mind sharing here on how you did the above?

Happy to, as Martin previously discussed you just set your Lambda, Overall trim and injector open time data logging rates at maximum then go to the overall trim page.
Then when the car is idling just put in 20% trim and it will go rich, take it out again, turn the car off, unload the data and just look at the point in I2 where the overall trim is added and then measure from that point to where the lambda trace starts to drop to rich in time mode.
Mine turned out to be 2ms injector open time at idle and a response rate of 0.45 seconds (pretty quick as its a rotary engine ).
Then put that info into the rate table of the Lambda close loop settings and enjoy all that closed loop goodness !

Martin,
I have a Lambda sensor in each rotor ( yes I'm greedy ) so I have been logging all of them and making adjustments to individual cylinders respectively, it would just be nice when I'm finished to have the 3rd rotor closed loop at idle like the rest but it is fine with only two.

I remember at one of the I2 training courses there was talk about Motec going away from using any onboard control for all this stuff and having it all CAN based ( you can run 12 Lambda sensors ? ) but wouldn't it be good if you could control all of those too

btw...at what speed do they they take your keys?

I think 35kms and above the speed limit its game over here in NSW Australia but I drive like a grandpa anyway so its ok for me, I even get people honking as I'm too slow ( usually doing some low load throttle tuning )

[robespierre]

Do you mind sharing here on how you did the above?

Happy to, as Martin previously discussed you just set your Lambda, Overall trim and injector open time data logging rates at maximum then go to the overall trim page.
Then when the car is idling just put in 20% trim and it will go rich, take it out again, turn the car off, unload the data and just look at the point in I2 where the overall trim is added and then measure from that point to where the lambda trace starts to drop to rich in time mode.
Mine turned out to be 2ms injector open time at idle and a response rate of 0.45 seconds (pretty quick as its a rotary engine ).
Then put that info into the rate table of the Lambda close loop settings and enjoy all that closed loop goodness !

Tat's smart I will try it out when my new sensor arrives.

[Merlin]

Hi 20B

I to love a good Na Rotary engine
I am involved with numerous rotary powered race cars here in Victoria
Most are IPRA RX7's with13b bridge ports..(including my own...M800,ADL,SLM)
and a couple of 20B sports sedans
All run MoTeC Products

One thing I have found is that the LSU sensor will go into shut down when its over heated
on my Chassis dyno if the sensor is Close ( less than 1m) from the engine it will shut down after about 15 secs on a full power run

From the data obtained from My RX7 show the exhaust temps are around 900 deg C max the sensor have a max temp of 750 deg C according a data sheet I have found

so be careful how close you have the sensor to the engine

John P

[20B]

Merlin,
I have regularly had my lsu lambda sensors up to 1080 degrees c on the egt on full noise with no issues on some of my turbo engines, maybe I'm just lucky
N/A 20B sure sounds good though !

[Martin]

What LSU`s are you running?

Ive had them Pre-turbo in the collector and they didnt shut down. Bosch spoec sheet says 930Degc operating max and 1030DegC Max

You can see your delay but just letting it run against a lean or rich site anywhere. +20% is a lot!, be careful of giving it too much fuel as it migh actually make it go lean instead of rich as it would misfire.

Easy way i think is to just use a fuel comp for RPM and make the jump in the fuel comp very sharp that you can see it happen as a comp and then later as a lambda reading.

maybe someone else has a good idea for getting a good change in La that you can measure the delay?

20B,
Lambda per Cyl in nice but shocking sometime when you see whats happening!

[20B]

Lambda per Cyl in nice but shocking sometime when you see whats happening!

Yes sometimes ignorance is bliss ! Its nice to know exactly what is going on in each cylinder and being able to make adjustments individually, I just have to tell myself to stop worrying all the time though
The cost of three Lambda sensors is way cheaper than an engine rebuild in my view !