problems with decel with 65#ers

[turbo_denali]

Hello i am starting to freak out and it aint going to get any better till i solve this. i have an 05 yukon denali with a rear mount turbo. i installed a walbro 255 pump and fast 65# shortys and the truck has monster power but goes very lean on decel. i have changed the flow rated vs KPA via the spred sheet but it would barly run. i lowered flow/KPA till it ran pretty good but still way lean on decel and the tune will not stay stable goes rich goes lean all below 100 KPA. do these Fast injectors just suck or did i miss some thing. i,m posting my sd tuning tune was hoping some one would look and chime in. oh and i had no decel issues with the old 39# injectors

[Ecotec2.4]

subscribed to hear an answer.

I did turbo install with 60's and right now same issue as you (scary).
Pegs uego way lean after boost, AFR's all over the place.
Next week before I get to look at it though

[turbo_denali]

thought it was manifold vac leak but sprayed wd around all injector o rings and mech guage reports 18" at 550 rpm and did not change nor did afr

[killer96z]

Probably decel fuel cut off. Its normal.

[Twitch]

It's not DFCO. I'm still new, but some of his fueling tables look lower than others I've seen on here.

[camaross22]

you need to make sure that your offsets vs vacuum vs batt voltage, short pulse limit and adder and minimum injector pulse are changed to match the injectors as well. As long as you used the excel sheet you should be fine with the flow rates, it is most likely in one of these tables, call fast and see if you can get some of the info. I know ive had a set of "upgraded fast ls7 injectors" (redrilled factories) for over a year and still only have the flow rate. These values are crucial when changing injectors.

[vortec]

Offset and short pulse adder tables need adjusted.Make sure your IFR is correct first.

[turbo_denali]

I have been on hold with fast's tech number for 1/2 and hour only to finally get to a human and be told that i needed to be transfered to fuel tech then after another twenty minutes got cut off. i have tried e-mailing them but no reply if i had know how well they supported there product i would have got the siemens 60#. and the VE tabels are low had to fake the IFR table to get it to run. just kept lowing by .9 till it held AFR at lite load. i am certin it is wall wetting but will just have to play with adder to see if i can fluk into a worhing setting. well heres hoping they get back to me and if they do i'll share the data.

[turbo_denali]

OK i have reset my tune back to where it should be and started to play with the offset vs volt vs vac table started by adding 25% across the board then 25% lower across board but no effect i did the same with the adder table same out come what would happen if a recurved my KPA vs IFR started at 6gps 0 KPA or so and scaled to 8.8 or so a 80 kpa. i imagin the ve would be all fricked up but might be stable. how does one tune the these dam tables.

[turbo_denali]

tune

[turbo_denali]

K started playing with the tables for injector settings set IFR as spread sheet and put back the factory VE table stretched it for 2BAR and started increasing offset vs volts vs VAC X 1.2 across table till started to get the afr i was after. then lowered short pulse adder and min injector pulse X.9 till it held good afr across the map my VE tables are virtualy stock and maf was only out a small amount. but when i hit 4# boost it goes into reduced power mode and no DTC. afr is ok till reduced kicks in.?

[Throttle]

first of all you cannot guess with injector data and second on a boosted setup your flowrate vs kpa is not scaled its level across the board because your intake is under pressure now.plus what is your fuel pressure set at on your boost referenced regulator?

[turbo_denali]

no boost refrence returnless system and i would LOVE to have exact data but this and the meaning of life seem to illude me. would love some one to look over my last scan for open loop i thought it was ok. well maybe f.a.s.t. will release the data to me(if they have it) but all the local guys tell me that they just keep moving up and down till its as close as they can get it.

[turbo_denali]

sorry closed loop and she is 62# at the rail

[turbo_denali]

i know its late but i did solve this. It was the fuel trims, the PE throttle enable was set to 90% (factory) and fuel trims where beating it back to stoic when boasted then going lean off boast as the trims where reeled all the way back. boost enrichment trying to get PE and throttle postion saying no and bring it back. set PE enable to 30% TP and works a treat no fighting with the trims. just to finish the post