Strange lambda reading ...

[Torque]

Hi Eric,

Interesting ... treshold values, more tables?
I don't think these are in Nistune, but for academic reasons it would be nice to have as much in there a possible.
(though not required for 'tuning')

As for Lambda, I find a voltage of ZERO very odd, at least there should be some mV present.

But anyhow, my Lambda-Sensor is damaged and not giving much output at all.
Strange thing is that the ECU does not throw an error.

Also with the (sensor) output being so low the ECU must be trying to alter the mixture to get Lambda right (in closed loop), but without success.

So I think the ECU secretly switched to the Open Loop values set for these cells (in Nistune the ghosted ones in the fuel map)

The car runs alright except for a somewht too high fuel consuption and some minor idle issues.
It seems my K-Value is set spot on then?

[Torque]

Hello,

I have changed the Lambda-Sensor today and now I have my
voltage readings back.

The ECU is chasing Lambda which can be seen on the log-graph (in purple)

Now there is just one question left:
It seems the ECU is not chasing Lambda while the TPS is in 'idle'
Is this a bug or a feature?

Thanks

[Matt]

I believe this is normal Nissan programming. This occurs on my R31 after reading the FSM

[Torque]

Hii ...

So rather feature than bug?

Is this the same on your R34?
I always thought when at idle you want to run at around Lambda=1 to
keep emissions low?

[PL]

I've seen this on SR20's too. Open loop at idle.

To check O2 sensor operation I always hold them just above idle.

Some engine do seem to run closed loop at idle though.

PL

[Torque]

Hi ..

Yes, once TPS is off (so lifted) the sensor is starting to move it's output.
(Meaning the ECU alters mixture to chase Lambda)

Hmmm .. now the question where would I set the A/F for idle?
Is this the value in the fuel map which is ghosted? (the 2nd value for A/F)
? (must be)

Some engines just don't idle well with Lambda=1 and need a slightly rich mixture
to achieve a smooth idle operation.

[PL]

I've never seen an actual idle mixture table for any Nissan ECU. So it's really a matter of balancing K Constant and Inj latency to get idle correct.

PL

[Torque]

I just wanted to add that due to the damaged Lambda-Sensor the engine was prone to sudden stalling when the throttle was lifted.

This is gone with the new senor being installed.

[Matt]

Must have been afftectimg ecu trying to go closed loop. At idle fuel map and latency are the main things to modify. There are only idle timing maps, not fuel