lambda control off M4 unit.

[bouma175]

I'm a bit lost, hope someone can help.
Just had the car on the rollers to remap, and we noticed that in the motec screen we had good readout from the Lambda probe, but we were not able to get lambda control on.
In the lamba portion of the screen the last line says lambda ctrl off.
We couldn't figure out how to turn it on after mapping was done.

[AdamW]

It would help if you posted your cal file and a log, however here's the basics:+

This is assuming you already have a lambda sensor connected and it reads properly in the live screens...
A). >Misc Functions>Lambda Control>Function. Must be set to 1 or 2. Function 2 (wideband control) will only work if your ecu has the "advanced options" enabled and also "advanced tuning" is turned on under >General setup>Misc setup 2.

B). >Misc Functions>Lambda Control>Parameters, all settings must be non zero and set so that the conditions are met under normal running conditions. i.e lambda control will only work if actual eng temp is between "lo eng temp" & "hi eng temp" & your injector DC is below "max duty cycle"

C). >Misc Functions>Lambda Control>Table. Must be non-zero in the cells/areas where you want lambda control to be active.

[bouma175]

Thanks Adam. I can work with this checklist.

Lambda sensor is connected and working. (gives live readout)
A: advanced options , OK.
andvanced tuning, OK.
B: lambda control parameters were all set.
C: table everything is non zero.

Reviewing the control parameters I saw the low ET and high ET were 50 and 70 degrees.
I will widen this to see if it has any effect.
Thanks again for the simple but effective guidelines.
When it doesn't work I will post my cal file.
Will take a few weeks, because engine and gearbox will be taken out for new gearbox.

[SprinterTRD]

If you are in the fuel screen then lambda control is turned off as the ECU assumes you will be adjusting he fuel.

[walkemazda]

I have also been having problems with my active Lambda. I have an M4 running a rotary engine. I have done all the steps Adam suggested, but am still seeing the Active Lambda Off message when on the main fuel tables. But based on what Sprinter said, I went over to the Lambda Tables and it shows Active Lambda On. So in theory it should be working. But idling in the shop, when I make gross changes in the Lambda Table around the 0% throttle / idle speed cell, it has no impact on how the engine runs or on the actual Lambda reading. When I make a gross change when on the Main Fuel page, the engine dies. So the question is, when running on the Active Lambda Table, is there some threshold of throttle position and/or RPM under which Active Lambda does not work? That's the only logical explanation I can think of on why changing the Lamdba value in the Lambda Table does not change the way the car idles!
Thanks in advance for the advice.

[AdamW]

as well as the conditions already mentioned there are some others listed here:



I suspect on a rotary with large injectors you might be below the 1.5ms condition at idle?

.

[SprinterTRD]

Also changing the lambda table will not make a change to the fuel straight away.
The long term and short term lambda trims also effect how the fuel is trimmed by the lambda table.

One more note on how the ECU starts lambda control, the ECU must see a lean, rich, lean cycle from the lambda sensor and must be at the correct temperature to start working.

Besides the lambda table trims should not be used to compensate for a bad fuel map.

What injectors are you running?

Have you set the correct injector dead time for the injectors?

Not having the dead time correct will effect how the injector operates at low injector duty cycles.

Also what is your IJPU set to?

[walkemazda]

Adam and Sprinter, thanks for the responses. With the assistance of Hannah at MoTec, we determined the active Lambda is working. Obviously I didn't understand there are conditions under which is does not respond.

In answer to your questions, I am running the stock '89 NA RX-7 injectors. They are Denso 195500-2010 injectors. The pulse width at idle is 2.1 msec, so I am close but not at the 1.5 threshold.

I have not been able to locate the desired injector dead time. It programed into MoTec at 4. The base programing was done by SpeedSource, so I suspect it is set correctly. Does 4 sound correct?

My IJPU is set at 10. Again, does that sound correct?

Thanks for the help.

[SprinterTRD]

The number 4 is a generic compensation curve for 16 ohm injectors. This still may not be 100% correct for your injectors.

The only way to get the correct curve is to have your injectors tested at the fuel pressure you are using.

An IJPU of 10 may be OK, all depends on what your biggest fuel number is in your main fuel table. The idea is to have the biggest number in the main fuel table around 90~95% by adjusting the IJPU, This gives you the best fueling resolution for your 0.5% increments.

Remember you can press F1 for additional information in the software..

[bouma175]

Sorry guys for the time out. I've been busy with work and had little time working on the engine.
I got the short term trim finally working.
It turns out that the short term trim is disabled when your in the fuel trimming window. (Thanks SprinterTRD)
When I checked the logfiles from test runs on the road I could see short trim active.
I still need to do some adjustments to the IJPU since I'm running to 99.5% in the fuel table.