For me, I'm running them at 43.5 as they are rated. Can't say for Double D.Originally Posted by ShelGame
For me, I'm running them at 43.5 as they are rated. Can't say for Double D.
Those are scaled for injectors, but I have found fine tuning those has helped a lot, it does essentially scale the entire 3D fuel tables, but my theory is once I get these two table where I want on the high rpm/ boost side, I can then pull fuel out of the 3d tables themselves where needed. I would rather run rich on the bottom and get WOT dialed as oppose to dialing that in and risking not enough fuel on top. Right now at 22-25 psi the AFR is 11.7-11.8. Right where I want them.
The 72 lb injectors are rated at 43.5 psi. I had all my injectors flow tested and this set was 768cc/ min or 73 lb. I am running my fuel pressure at 48 PSI, so I have them scaled for 76.8 lb to equate for the higher fuel pressure.
It looks like the Density Facotrs are not scaled correctly in my TIII cals. I'm not sure the cause, but they should be 0x2151 (8529 decimal) for 3-bar with +40's. They are set to 0x233C. Which would be much richer than expected. By about 7% it seems. Not huge, but with big injectors the effect is maybe exaggerated.
The value for a 3-bar, 72pph cal should be 0x1810 (6160 decimal).
DoubleD/Pat, please update your cals to these values respectively and see if it helps.
Both Density Factors can be the same. The factory cal had the WOT DF a little bit lower. I'm not sure why, but I made them the same. The effect is to a add a little more fuel at WOT.
The cause for the discrepancy is just the injector size. The template uses the 34.9 lb size. If you assume it's 33 lb, you get the lower number. I believe the stock TIII does in fact use 34.9 lb injectors. Can anyone confirm?
Thanks for your help. I'll try to check it out tonight.
Gave it a try...no dice. Scaled to 72's, moved both density factors to 6160 dec. Car started cold, idled fine for a bit. As she was warming, I turned it off to see if it would restart and no luck. Didn't bother trying to drive it.
Edit: car restarted after it cooled a bit. Decided to take up the road a bit to see what the drivability was like. It was extremely lean, everywhere. As it got to operations temp, it was idling in the 17.5:1 and leaner. At part throttle, would hang 16:1, hit it once, went to 14:1 and as it came into boost, went over 15:1. After getting home, wouldn't restart...
Is it possible the fuel density needs to move the opposite direction?
Last edited by Pat; 07-16-2015 at 09:16 PM.
What was it before you made the change?
Richer. It would idle around 15:1 until it got warm and the idle started to oscillate around 2k. When it did that, it would be dead lean (18:1+). Didn't get much run time before the issues would start, but it was on the lean side at wot, but around 12:1.
What was the density factor value before the change?
For reference, my 72lb injectors @ 48 psi. Full throttle factor is 5891, part throttle is 5589.
When scaled for 72's, MP Tune scales the density factor to 6514.
So, 6514 is too rich, and 6121 is lean. Sounds like stock injectors must actually have flowed in between 33pph and 34.9pph.
Maybe split the difference and try again?
Last edited by ShelGame; 07-17-2015 at 07:58 AM.
I will keep tinkering, but with the cal scaled for the injectors, I haven't experienced it being too rich. The only Tim it was rich was when I loaded up the base +40 cal and ran it with the 72 lb injectors.
I'm flipping through tables while drinking my coffee this morning and noticed the Fuel/Running/CounterFuelEngRunning FromRPM table has some break points in it 500 and 1000 (ish) rpm. Is that right? It's not a linear at all.
I know I'm a newbie here, so I very much appreciate all of the help/suggestions. Thanks!
Last edited by Pat; 07-17-2015 at 06:46 AM.
So, it was lean even at the 6514? I guess I read it wrong.
The CounterFuelEngRunning is related to the cold start stuff, I think. I'll have to double check.
Yes. Not as lean, but definitely on the lean side.
Pat, Are you still using the +40 3 Bar Template? Try starting with the stock template. I started with the stock template and have refined it pretty far. If you would like I can send you my template and then you compile it and put it in the car and see if it helps. What fuel pressure are you running?
Yes, I have been starting off the +40/3 bar template.
I'll pm you my email addy. I'd love to compare to yours. Will it matter that I'm '91 sbec and your '92 sbec 2?
Thanks!
Pat
That's a question for Rob, can tunes be interchanged between the 2 ecu's if you use the proper assembly file to compile it?
From my experience, I would try starting with the stock template, I had a ton of headaches trying to use that template, I have no idea what is wrong with it.
No, it won't work. It might be possible to make a 'universal' template; but MP Tune looks for an association to a specific .asm file.
Since he's running 43.5 psi fuel pressure, the equivalent Density Factor would be 6223 to your 5891. But, he's lean at 6160 and 6514. So, 6223 probably isn't much better. Makes no sense to me. Something isn't right.
Pat - Can you send me your cal?
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