Question on tuning LARGE INJECTORS

[RacerChris]

I have 60lb/hr Mototron injectors and I am having difficulty tuning below 40KP of manifold pressure. During AutoVE it always tells me to subtract like 20-25% of the table below 40KP and everytime I am off the throttle my engine runs WAY rich (10-11:1), I remember reading on here that I can play with the Pulse Width in that area in the V vs RPM table but I have also read not to.
Could anyone shed some light on this for me?

[TAQuickness]

Click the reference material link in my sig, then "tuning for big injectors" - lot's of good info and might be all you need. If that doesn't work, post back here.

[RacerChris]

Well I am going through your list of things to do and I am having small amounts of luck but no major progress. It does feel like I have cleaned up the idle a tad but I still get overly rich on decel.
Does anyone know if my injectors are plate style or pintle??? Also... Does anyone know what is the minimum pulse width I should command with these?
Thanks again!

[RacerChris]

Well I did find some info on these injectors...
On time is 1.14ms and off time is .85ms. So I gues I should change my default Minimum Injector Pulse Width to 1.14???? I am still confused though on what I should set my Low Pulse Threshold to though... Any ideas?
Also... I started upping the flow rates under 35KPA and that did make a bit of difference. No where near right yet but getting there. I think I went a little too far the first time though because I went to start it and I got nothing but cranking!:bangin:

[TAQuickness]

What's your fuel pressure?

[RacerChris]

Stock at 58 PSI, I guess it would help if I had a set pressure of 43 PSI since thats what these were rated at. The fuel system is stock except for a walbro pump and the injectors.
Anyone know if they make a LS1 style fuel pressure regulator set for a loer pressure that I could swap into the gas tank????

[SSpdDmon]

Well I did find some info on these injectors...
On time is 1.14ms and off time is .85ms. So I gues I should change my default Minimum Injector Pulse Width to 1.14???? I am still confused though on what I should set my Low Pulse Threshold to though... Any ideas?
Also... I started upping the flow rates under 35KPA and that did make a bit of difference. No where near right yet but getting there. I think I went a little too far the first time though because I went to start it and I got nothing but cranking!:bangin:
The actual minimum on/off times of the injector are the min pulse width PLUS the battery voltage offset PLUS the short pulse adder. With my stock internals LS1, I need a pulse width of 1.6~1.7ms for a stoich idle with my Motron 60s. I had to play with the voltage offset table and zero out the small pulse adder to get the idle AFR to a reasonable level.

[RacerChris]

The actual minimum on/off times of the injector are the min pulse width PLUS the battery voltage offset PLUS the short pulse adder. With my stock internals LS1, I need a pulse width of 1.6~1.7ms for a stoich idle with my Motron 60s. I had to play with the voltage offset table and zero out the small pulse adder to get the idle AFR to a reasonable level.


I will be sure to adjust this tonight and try a few logs. I will report back tomorrow.
Thanks again

[exploder]

I have 96lb low impedence injectors in mine....here is my tune file and I have them running good at idle.

[RacerChris]

I have 96lb low impedence injectors in mine....here is my tune file and I have them running good at idle.

Thanks for sharing your tune, I dont believe it will do much good though because our injectors will have completely different personalities.:gossip:
However, after looking at your tune I noticed that your VE tables were pretty spiky, are you finished tuning it??? If so you may want to take another go at it and do some smoothing.

[exploder]

No I am not done tuning the ve. I was told not to do any smoothing though....maybe I should.

[Bruce Melton]

I learned the hard way that the spray pattern of many of the SVO and non GM spec injectors CAN present a problem because you are spraying onto the floor of the intake runner where the fuel pools until you accumulate or blow it loose. The GM and later FAST spec injectors seem to spray higher toward the back of the valve thus are are cleaner burning. Watch for the decel black puff when using SVOs and note how tuning at idle results just seem sporatic and inconsistant.

I don't sell injectors so don't shoot the messenger. Just saw a dramatic difference going from SVO 30,36,42s to the GM LS7 and FAST 50s which use a different spray pattern.

[RacerChris]

No I am not done tuning the ve. I was told not to do any smoothing though....maybe I should.
Maybe I have thr wrong info but I always do small amounts of smoothing because the engine will respond better if it quietly goes from one cell to the next instead of beating down the door screaming more fuel/less fuel!!!!

[joecar]

That VE table is too spikey...

need to smooth it completely and start again, collect better data (no sudden throttle openings -- smoooth) and apply BEN filter (think about what has to be eliminated... any transitions that would cause a lag between wideband sensor below and PCM computation from MAP/IAT/ECT above... if PE is enabled, make it the same as the last few columns of OL AFR table)...

generally after applying AutoVE BEN, the VE table has some very minor spikes and doesn't really require smoothing.

[exploder]

Here is a copy and past of my old IFR table from when Ihad 60lb. injectors a long time ago.

69.26006
69.69410
70.12814
70.56218
70.99621
71.43025
71.86429
72.23632
72.67036
73.10440
73.47643
73.91047
74.28250
74.71654
75.08857
75.52261
75.89464

Min injector PW =1.246 across the board

Default injector PW= 1.246 across

Short pulse limit = 3.921

Flow rate modifier vs. volts = 1.00 across

[joecar]

Have you tried with negative small pulse adjust...?

[RacerChris]

Ok, So I zeroed out the min-inj. pulse width adder, I adjusted my min-pulse width to 1.55 and I played with the voltage correction table. What I ended up with was terrific results! It is now calling for more fuel in the under 40KPA area. I did a couple of logs making adjustments each time and I feel I got the VE table in pretty good.
Just wanted to say thanks to all that helped me on this one :cheers:
Now I just need to start playing with my timing tables to get rid of this damn light bucking when my converter is locked up!
Thanks again!

[exploder]

Let me know what you do to fix the light bucking because I am having the same problem with mine.

[RacerChris]

Let me know what you do to fix the light bucking because I am having the same problem with mine.

I believe its because of timing in the off throttle area.
I will be making some changes and letting you know what happens.

[Goldfinger911]

I am running Lucas 42lb injectors at 64psi which makes them around a 50lb injector. Feel free to take a look at my tune (linked in my sig) I have them running very good, no stalling, perfect starting, 13.5/14:1 decel, 12.8:1 at WOT and almost dead-on VE Table.

Exploder- Dude, you gotta do something with that VE table. The problem with a super spikey VE table; is it makes changes to fueling so quickly, that further logging, unless it is filtered and %corrected only makes things worse.

[RacerChris]

Thanks for the help although I got my injectors pretty much were I think I need them. VE is spot on!
Thanks though