For you guys with big injectors, when you adjust the tune for the injectors, do you adjust anything in the tune other than the injector flow rate? I have some Bosch 60# @ 3bar injectors from FIC. Using their supplied data in my tune makes it so I'm hitting a minimum puslewidth limit during decel, causing it to be rich. Everywhere else it's fine after a little MAF tuning.

The pulsewidth during decel is 1.83-1.77ms. It is flat, but drops in nice steps of ~0.015ms even though the MAF frequency, RPM, and fuel trims stay roughly constant. After about 15 seconds of decelerating at constant RPM (downhill) the AFR will eventually get back to stoich even though the fuel trims are maxed out negative. Everywhere else the pulsewidth is bumpy instead of flate. This indicates to me I'm hitting some sort of lower limit.

My tuner says in the thousands of vehicles he's tuned he's never had to adjust the minimum/small pulse settings of the injectors. I don't know the math to calculate final pulsewidth, so I don't know how the min pulsewidth limit is being computed, hence I don't know what values FIC gave me could be causing this issue.

Their data is attached. Thanks!

 

There was one table with the Voltage adjust that i changed one time.. i cant rem what its called.. it helped stumble coming to idle.

 

i use hp tuners. if you are using something different your results may vary.

with big injectors, there are 4 tables that i like to have data for. flowrate, offset, short pulse adder, and min injector pulse. i didnt look at the file you attached, but that is all information that should be provided by the injector manufacter.

another reason for rough running at lower pulsewidths comes from the quality of the injector. i am not saying this is the case for the ones you have, as i have never used them. the larger hole in the injector becomes harder to control at low speeds, causing inaccurate fueling.

this is the reason that you will hear a lot of tuners prefer injector dynamics. thats pretty much all i use in projects, despite the cost. plus they provide all the data in an accurate easy to import format.

if i were you, i would drop your minimum pulsewidth to 0.75ms and see if that helps. it certainly wont hurt anything.

 

Which table are you talking about? There is B4002 Injector Voltage Correction and B3701 Offset? Right now my B4002 is all 1's, which I think is also how it is stock. And B4002 varies with voltage and MAP, higher values at low voltage, no variation with MAP since it's a manifold referenced FPR.

I believe they provide all the values you stated. There are a few different tables labeled minimum/small pulsewidth something, I have no idea which to adjust. I can't seem to figure out how these values correlate with the pulsewidth I'm logging.

Perhaps I'll try reducing B9021 Minimum Transient Pulsewidth, it's set to 0.89ms right now which is stock.

 

another thing to consider when you are logging pulsewidth is that there is going to be a commanded pulsewidth and an actual pulsewidth. it sounds like you are using efi live, so your nomenclature is probably different, but there are fuel adders that are going to skew what you are seeing for pulsewidth.

 

I believe I am logging actual pulsewidth, and commanded pulsewidth has to be calculated from other parameters. I have not attempted to calculate the commanded pulsewidth.

 

Well I changed B9021 Minimum Transient Pulsewidth to 0.121ms to match the Minimum Injector Pulsewidth tables and it's slightly better than before. I can get lower pulsewidths around 1.55ms now, but it's still going rich on decel with the fuel trims going max negative (-12.5%). The pulsewidth log is still pretty flat during decel so I think I'm still hitting some minimum limit.

 

I knocked 10% off the voltage offset table B3071 (adds pulsewidth based on manifold vacuum and voltage) and it helped greatly. With zero MAF tuning my fuel trims were -3.1-1.6, no maxing out on decel. It's still going a little rich on decel but maybe that's normal?

 

Mine goes lean on DECEL, but my VE table has some low number on the left side tho. i think my injectors are 84 or 91#? ill have to look

I cant rem the table i was talking about, ill have to look next time i find my laptop.

 

check your decel fuel cutoff tables. normally the truck should cut fuel completely during decel and you will see your afr go lean. some tuners change these settings to get rid of the popping that can occur when this happens.