Easimap for Diagnosis

[AlastairA]

Hi John - second attempt (with coolant temp added).

 

 

[John Vine]

Thanks, Alistair.  Do you know what the coolant temp was at the start of the oscillations?

JV

[AlastairA]

It measures as 42 degrees C, John.

[John Vine]

Thanks, Alastair.

About the same as before, then.  As James suggested, perhaps CC reduced it from 60C when they moved to the 9A4?  I'll ask them and post back.

(Apologies for mis-spelling your name!)

JV

[aerobod - near CYYC]

Hi Alistair,

It is good that you seemed to have solved the main issues by doing an Easimap reload. It is still worth updating the templates from 9A4bf45a to 9A4bf91a, as you always want to match or exceed the template version in the ECU with the software version, to ensure bugs and feature coverage is up-to-date.

With the switching point where closed loop operation is started, you don't need to match the oscillation value to the coolant temp directly, the Lambda Status panel will indicate that the coolant temp is too low or heater timer has not expired, when all closed loop conditions have been met it will change the status to "OK" and enter closed loop operation, so you can just scroll through the data until Lambda Status is "OK" at a given data point.

In terms of the Lambda values only changing between 0.96 and 1.04, this is expected behaviour with steady state engine speeds in closed loop operation with a narrow band Lambda sensor, here is a typical voltage (i.e. Oxygen Raw voltage) to Lambda graph:

You will see that the 0.5V Oxygen Raw nominal average output value is on a very steep part of the curve, only a small amount of fuel addition is required to drive the voltage to 0.8 to 0.9V (when the values are in the 0.96 rich Lambda range), then only a small amount of fuel reduction to drive the value to 0.05 to 0.1V (when the values are in the 1.04 lean Lambda range). The key is that the Lambda values measured need to be either side of the stoichiometric value of 1.00, so target Lambda has to be 1.00 for proper closed loop operation of a narrow band system. When in open loop operation, the target Lambda should be 0.00, as this indicates to the MBE ECU that closed loop operation should not be attempted.

[AlastairA]

John - appreciate you contacting CC to chase down the apparent change in coolant temperature switch point.

James - thanks for the detailed explanation and I'm glad to know everything seems to be as it should be, but moreover I've learned so much from the collective wisdom of helpful club members. Much appreciated. I'll continue to work on how to post high resolution images....!

[John Vine]

#29

This was the question I asked:

Closed-loop trigger temperature MBE992 v MBE9A4Using Easimap to track lambda sensor operation versus coolant temperature, I can see that the 992 on my 2008 R400 enters closed loop from cold at around 60C. However, another owner (2022 420R) has recorded the equivalent temperature on his 9A4 as around 42C. Does that sound reasonable? If so, is that the setting you now use? But if it's too low, what would he need to do to increase it?

This is the reply I received from ever-helpful Tony Mills:

The trigger temp is historically set at 60 but it was brought down in recent times on 9A4 to about 40 to help with cold start control.  The setting of 40 should not be too low. Any apparent problems would normally be down to another issue such as throttle voltage setting.

JV

 

[mph]

(comment purely to sub to thread)

(plus I have a knackered o2 sensor and I would like to fathom out how to work out if the new one is working  )

[John Vine]

#33  Do you have the MBE cable (plus Easimap)?

JV

[mph]

No JV. But - I do have a BTLE OBD reader that works with the Cat. Just managed to find the O2 sensor voltage and after swapping sensor for a new one I see the behaviour described here. Temp got to 60, and it would drop from circa .8v to 0.05 and the back up again. Up and down, up and down. The old one was stuck at .9v. 
 

Sorted :)

* reader is a OBDlink MX+ It works nicely with RaceChrono too, which is how I get the RPMs and throttle overlays on my track day videos 

[AlastairA]

Many thanks for the follow-up JV