What Happens to My Tune when?

[kdietz]

I change injectors from 5.7 to 4.89?

I assume my TSII+ can tweak any VE"s changes!

[kdietz]

Well, I'll answer my own question!

Just made the change...did a 10 minute data run and I only had 3 cells that changed. It might me my imagination, but it did seem to run a little smoother at low rpms and off throttle....throttle response was very crisp.

[FLTRI]

WOW!!! So you changed the fuel output of your injectors by a significant amount (almost 15%) and it only changed the mapping in 3 cells??
Sumpin' ain't adding up.

[kdietz]

That's right....my injector size was set at 4.42 when I was running the 5.7's....I didn't change the setting when I installed the new 4.89 injectors....could that have something to do with it?

Also, I only did a 10 min data run and didn't do any WOT running....just local streets to see how the low speed response was going to be.

[FLTRI]

OK, heres' the best way to look at what has been done with the change of injector sizes.
Think of it as a carbureted bike with rich jets. Then you replace it with lean jets. However when you ride the bike your system tells you it's virtually the same AFR.

Now, by telling the system you have 4.42 gps injectors when you actually have 5.7 gps the actual fuel output into the engine is about 25% more than if the injector size was set to 5.7 gps.

If the bike was auto-tuned with the software set to 4.42 and that number was not changed then the new, smaller injectors has caused the AFR do be considerably leaner, which really makes one wonder why the auto-tune system has not compensated in every cell.
HTH,
Bob
PS - My suspicion is that you will need to ride the bike 100-150 miles at all engine speeds and TPs to get the auto-tune to recognize and make appropriate changes.

[kdietz]

Bob you are right....something wasn't right!.....my bad 

I wasn't reading the correct data runs.....I mistakenly downloaded the most recent file before the injector change....no wonder it looked near normal

I'll do it correctly today

[kdietz]

Well...after my brain fart loading files the other day, I can now say that nearly every cell has seen some correction

[uglyDougly]

  Injector sizing isn't an absolute. So, choosing an injector size will inevitably require some adjustment. But, that's what the system does well.

   My experience with injector testing often tells me that the manufacturers informationis in error.

  F'rinstance, the static flow I get for the older Weber Pico H-D injectors (IWP043 and IWP162 which are as identical as any injectors get) shows that the injectors for the SE 50 TB flow 32 lb/hr and the Picos flow 34 lb/hr. Somebody listed the information indicating that the SE 50 injector is larger than the Pico.

  Same for the Ducati injectors where they are listed as 480cc/min (IWP069, the yellow ones) and 490cc/min (IWP189) which is 2% difference, while my tests indicate 48.4 lb/hr and 54 lb/hr and thats 11.5%.

  The point of all this is that none of this is chiseled in stone and the injector flow values in your tuning software need to be adjusted so it works. It's not a religious experience, it's science, or engineering, er something.

  Doug

[FLTRI]

Doug,
Without a doubt, IMO this is the most important statement: "the injector flow values in your tuning software need to be adjusted so it works".
Bob