Z32 ECU, high load trigger?

[Torque]

Hello,

I was wondering what actually makes the ECU go into 'forget-about-Lambda-mode'?

By that I mean when does the ECU stop chasing Lambda and uses the 'high-load' values for fuel/ignition?

Is it all just triggered via TPLOAD? What is the threshold then? Where is it defined?
(is it that 'bit' set in the fuel map?)

Could I force the ECU to chase Lambda even under high load?
(Would be nice for an economy mode map)


Cheers,

Andrew

[PL]

This is definitely one for Eric, but my understanding was that most ECU's will chase closed loop based on the flags in the fuel map itself.

PL

[Torque]

This is definitely one for Eric, but my understanding was that most ECU's will chase closed loop based on the flags in the fuel map itself.

PL

Hi!

Thanks for the answer.
I had a look at your document and it seems it is based on the flags in the fuel map.
(apart from warmup and idle)

[Eric]

> Could I force the ECU to chase Lambda even under high load?

It's possible, but I don't think you'd want that !
running lean under boost (>12.0 AF) is asking for trouble...

if you want fuel economy under boost, use the boost cut table or remove/disable the turbo

[Torque]

Hi Eric,

Of course fuel consumption is only secondary to a performance car.
But I was interested to find out how the ECU determines to either ignore the Lambda-Sensor or not.

So in theory I could set the O2-Flag in the fuel map and the ECU would then chase Lambda?


And I though that lean would be anything >14.7?
At what AFR is best performance usually achieved?

> Could I force the ECU to chase Lambda even under high load?

It's possible, but I don't think you'd want that !
running lean under boost (>12.0 AF) is asking for trouble...

if you want fuel economy under boost, use the boost cut table or remove/disable the turbo

[PL]

I've had SR20's that chase closed loop too far into the map and it makes them feel like horrible laggy things. Definitely not recommended. And as Eric said - if you go leaner than 12.5:1 or so on boost then you're asking for trouble. Big expensive trouble.

What you can do is disable closed loop at cruise and lean them out beyond 14.7:1 at light cruise. Ideally you want to be monitoring EGT cos lean mixtures will increase EGT's. Play with IGN timing too - often you can improve fuel economy by adding some timing. Hard to measure without some sort of drive computer though.

PL

[Matt]

From what we have seen so far there are various conditions
- O2 sensor flag
- O2 temperature value
- O2 flags in fuel map

After that you have AF Alphas viewable in consult which adjust based on the O2 feedback

When you use the throttle etc and it throws out of closed loop most likely based on ECU checking TPS, RPM inputs and using timers. However I dont know the specifics without reading up on the Nissan patents for how they control that stuff. If you are interested, google for Nissan ECCS patents which will go into great detail about how a lot of the algorithms in the ECUs work

[Torque]

Nissan ECCS patents

Thanks ... will definitely have a read