Tuning via KCONST

[Torque]

Hello there,

After a 1000 EMails to Matt (sorry!) and many hours comparing Z32 and R33 parameters
I finally have a stage were I would say the car performs as before.

It still ran a bit flat and when I started the engine from cold (20C) there was a lot of misfiring
and the engine was not happy during idle warmup.

The symptom went completely after the engine got to around 50C.

I started to experiment with the Injector Multiplier and changed KCONST from 172 to 190.
With this figure cold start was smooth and the car ran much better than before.
And now under slight boost the engine was nice and smooth.

Here's my question:
Is 172 to 190 a big increase?
And is it a valid approach to up the multiplier?


Would someone (Matt, Ed, ?) have a look at my attached logfile.

I could not really floor it, so just drove under mild boot.
(you have to scroll to that part)

My car is almost standard, but running 1 bar.
Z32 AFM is on its way.
I noticed the AFM almost reaching 5 volts.


Many thanks,

Andrew

[PL]

Doing it like you have is perfectly valid. That's how I tend to approach things too. Get it started and then open the K constant window, select "auto" and hit the +/- keys until it's happy. This will usually get things in the ballpark. Then once you're on the dyno you can do minor tweaks to K on combination with fuel map and latency changes to get things spot on.

PL

[Mr666]

you should be looking more at the latency figure. It sounds like you are to lean when cold and to lean low down, increase the latency by 10 at a time until the engins gets smooth. You may only have to increase it 20 or 30 as this will make a big difference up to 4500 rpm, all the while watching your wide band O2 readings. After you do this then it will allow for the K value to be reduced again. PM me if your not sure what I'm talking about.

David

[Torque]

Hi there (PL, David)

Thanks for the thoughts.

I have not experimented with the injector latency yet and it is set to the standard value from my GTST.
I do grasp the concept of the K-Constant but how would increasing / decreasing the latency affect the engine performance?

Nonetheless latency seems to be an interesting value to tweak.


Andrew

you should be looking more at the latency figure. It sounds like you are to lean when cold and to lean low down, increase the latency by 10 at a time until the engins gets smooth. You may only have to increase it 20 or 30 as this will make a big difference up to 4500 rpm, all the while watching your wide band O2 readings. After you do this then it will allow for the K value to be reduced again. PM me if your not sure what I'm talking about.

David

[Matt]

Latency is an addition to the injection time, whilst K const is a multiplier over the entire lot

Latency will have effects mainly around idle where the injection multiplier is small and noticed more. K constant will affect AFRs over the entire rev/load range by the % you change it

[Torque]

Interesting ... I will have a closer look at this once my car got its tune ..