Hondata

I have just got my JDM PRC with wideband working 100%.

So its time to tune the fuel using the wideband air/fuel sensor.

So I go for a drive 4th gear pull from 2000rpm until redline. I do this a few times whilst saving the datalogs. I then compare the target lambda with the recorded and view what % adjustment is recommended.

The question is have is - do i conduct this drive in open or closed loop?

Tune the car in open loop, when done, put it in closed loop.

Spunkster wrote:Tune the car in open loop, when done, put it in closed loop.

Is the only reason for this to be done is so the Long Term Fuel Trim does not come into play?

So that both the short and long term fuel trims don't change the fuel.

The reason I ask is because I find it easier to tune in Closed Loop.
This way I'm always at 14.7:1 and never really lean or rich at part throttle.
I've done it this way on my S300 and now my K-Pro.
Currently my Long Term = 0, Short Term +-3% & WOT is within a few percent too.

I adjust my part throttle fuel according to the Short Term figure at any given constant.

I guess there's more way to skin a cat...

Thanks Guys

Ian - you make sense - I am just tweaking now - but tuning in closed loop even with part throttle over the widest possible MAP range seems sensible. Then I look at the trimming is occurring and tweak where necessary.

How many hours do you need to run the engine before a "long term" trim becomes evident?

thanks
Kevin