TGP Code Injector flow vs Base fuel constant

Joseph Upson · 05-01-2008, 09:22 PM

The trend has been to change the fuel injector flow rate, flow per single pulse and base constant at desired EGR.

If both flow rate settings work properly, there should be little to no change of the base constant required because you've effectively accounted for the injector size increase with the two prior settings, lowering the base constant afterward should effectively lean out the mixture.

So except for a small change of the base constant, it should remain pretty much the same plus or minus a little fine tunning, in other words ther is no reason my base constant should be as low as I have it set; 40 which I arrived at by listening to idle however during a test drive it appeared to be very lean and now with WBO2 monitoring at part throttle in neutral it is going as high as 19:1 so the base constant is definately going back up to normal.

That explains the hunting during idle.

Am I reasoning correctly?

I also accidently made a single inject calculation based on the difference in engine size instead of the difference in injector flow rates.

**SappySE107** · 05-01-2008, 10:54 PM

Go set your injector flow rate and flow per single pulse to FFFF in the hex, or 0000. It does nothing. Constant vs EGR is the only injector constant I know of.

Joseph Upson · 05-01-2008, 11:05 PM

Quote:

Originally Posted by SappySE107

Go set your injector flow rate and flow per single pulse to FFFF in the hex, or 0000. It does nothing. Constant vs EGR is the only injector constant I know of.

Thanks for that info, I'll make the proper scale based on the difference in flow rates between the injectors in the EGR vs BPC

merlot566jka · 05-01-2008, 11:56 PM

woah, foreign language alert.

Joseph Upson · 05-02-2008, 12:52 AM

Quote:

Originally Posted by merlot566jka

woah, foreign language alert.

That's straight talk. First I made a correction for the injector size increase as if it were being used for the 3.1 which brought the BPC down to about 56 from 105 because the injector flow rate increased by nearly 50% so I reduced the BPC by the amount of increase in injector size.

Then I calculated the increase in engine size and increased the new BPC by that amount to arrive at 70 which is 30 points higher than what it was set at previously so I'll pull fuel from the tables from here and add wherever necessary. Hopefully I will be much closer than previously.

**SappySE107** · 05-02-2008, 02:06 AM

Do you know the correct math for BPC? I have the equation, and actually did it a long time ago for the mustang injectors. I have never been able to do it since.

Joseph Upson · 05-02-2008, 07:56 AM

Quote:

Originally Posted by SappySE107

Do you know the correct math for BPC? I have the equation, and actually did it a long time ago for the mustang injectors. I have never been able to do it since.

I just divided it out to number of BPC points per litre for the 3.1, multiplied it by 3.9 then reduced it by the amount of injector flow increase above the stock injectors.

**SappySE107** · 05-02-2008, 08:58 AM

Base Pulse Constant Vs Desired Egr Constant =
1461.5 * (egr Factor)(liters/cyl)/(injector Rate)

Injector Rate Is In Gm Per Sec

Joseph Upson · 05-02-2008, 11:07 AM

Quote:

Originally Posted by SappySE107

Base Pulse Constant Vs Desired Egr Constant =
1461.5 * (egr Factor)(liters/cyl)/(injector Rate)

Injector Rate Is In Gm Per Sec

EGR is disabled.

33.7 lb/hr * 1hr/3600sec * 16 ounces/lb * 28.4gm/ounce = 4.253688 grm/sec

3.9L/6cyl = .65 L/cyl

(1461.5 * 1 (egr disabled) * .65L/cyl)/4.253688 = 223.33

That's just a tad bit high isn't it?

Stock is 105 in Tunerpro and Tunercat but Tunercat has another BPC value listed under constants that's about 180 suggesting it has a BPC constant factor that either is missing from Tunerpro or is synonymous with the Gal/hr entry in Tunerpro. Usually Tunercat is pretty good about being spot on in that if the value is available to be changed it will have an effect. Plus, 180 is much closer to the calculated value above if I did so correctly.

Joseph Upson · 05-02-2008, 08:02 PM

I just upgraded to TunercatRT to see if I'll have better luck tuning with it. I just checked the BPC in the constants menu and it is registering 233 after the adjustments I made in TunerproRT so there is a units difference I guess. Since the test drive improved and the AFR gauge is still showing a bit rich I'll lower a little at a time to see if the rich condition clears up.

The rpm vs VE table seems to work pretty well so far.