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  • Member For: 21y 11m 2d
  • Gender: Male

Dont worry about those figures too much.

How do you tune your idle /cruise. THis is a quick summary of how I sort of do it.

In the absence of injector data I start juggling the voltage offset and lo slope to try and get the idle at stoich and at very low rev, low load cruise at stoich (one that should have you below the breakpoint. (I am yet to calculate exactly at what revs and load you would switch to hi slope)

I only use one offset figure for all voltages on the FG as the FG falcon maintains a very steady voltage with the way it is regulated. You might not be able to do this with pre FG as they use an alternator regulator where the voltage varies a bit more.

I can get my idle to trim within +/- 3% of stoich with 1500cc inj

If the above does not make sense I will try and clarify.

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  • Member For: 11y 11m 1d
  • Gender: Male
  • Location: Liverpool

To be honest, I have only been using the low slope to get it to idle at (around) Stoich with minimal fuel trims and the hi for WOT.. I have just used the voltage tables from the Injector Dynamics spreadsheet.. I know this is not the ideal way to do it, so what should I be doing with the voltage table?

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  • Member For: 21y 11m 2d
  • Gender: Male

I don't have it all sussed but will tell you what I do. I would use the injector spreadsheet as a starting point.

The voltage offset influences fueling at idle and has a diminishing influence as revs/load rise.

Lowering the offset leans it out and increasing it richens it and has its biggest influence at idle.

The lo slope influences the fueling in the lo slope area so from idle to breakpoint.

So if you want to get 14.7 at idle and cruise it takes a bit of juggling between the two to get there.

If you are at 14.7 at idle but when you cruise its at 18 then you would have to richen the lo slope but then you will be richer at idle so then you will have to lean out your voltage offset and you do this until get it trimming to 0 on both idle and very light cruise.

I sometimes even increase the breakpoint number so I know that I am always on the low slope. I guess you could even use the same Hi and Lo slope to dial in the idle/cruise areas and only dial in the hi slope last.

As I said before I just use one offset figure for all voltages for the moment as my FG sits very solidly on 13v.

Hi slope is easy.

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  • Member For: 11y 11m 1d
  • Gender: Male
  • Location: Liverpool

Appreciate that tranna, I'll have to have a sit down and have another play..

I'm guessing a good start would be to log battery voltage and see exactly what it's doing throughout the rev range and load points..

Mine sits pretty steady at 1.0 Lambda at idle and cruise as it is at the moment, I guess Paul Yaw has really done his homework haha

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  • ...JD TUNING ADELAIDE...
  • Gold Donating Members
  • Member For: 16y 9m 1d
  • Gender: Male
  • Location: Adelaide

If u have GENUINE id's use the latest spreadsheet its 100% bang on and very plug n play

Had the chance to play with it the day rob herrod got it and its tip top

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  • Member For: 11y 11m 1d
  • Gender: Male
  • Location: Liverpool

Unfortunately I'm not.. Brand new xspurt 1000's for $300 I couldn't say no... I just have to put in the effort to make them work..

I used the data from that new spreadsheet though, very easy to use if your changing the base fuel pressure, also to get a Stoich value for different ethanol contents

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