tuning for bigger injectors

[1988montecarloss]

recently went from 36lb/hr to 50lb/hr injectors in my car and entered all injector data from a thread on here and car runs super rich at idle and slow cruise and bucks and almost stalls out, do i have to change the VE tables even when its in open loop? i thought it would run at commanded airfuel in open

car is a gen 3 6.0 swapped monte carlo tuned in speed density

car ran great before injector change just went to bigger injectors due to running out of fuel up top

sorry if this is a silly question, new to hptuners

[5FDP]

Yeah, you'll still need to update the tune for larger injectors. Just pull like 5% away for starters and see where you sit on the wideband.

[danmw2003]

I had good luck just logging LTFT and using those corrections to calibrate VVE and MAF, when I did my injector swap. Im a bit of a noob though, so there may be a better way to do it, I just haven't had any luck tuning any other way. I struggle with "steady state" being a manual trans, and being on and off the throttle in between shifts. Using LTFT is easier for me

[1988montecarloss]

Yeah, you'll still need to update the tune for larger injectors. Just pull like 5% away for starters and see where you sit on the wideband.

ok ill try that tomorrow and update with what i figure out

only other "big" question i have is how do i setup my vcm scanner to read my PLX wideband? i have an mpvi2 so do i need to use my prolink for that? or is there another way

[1988montecarloss]

good to know, luckily i have a manual valve body th350 so i can hold gears

[Matt Vardaman]

ok ill try that tomorrow and update with what i figure out

only other "big" question i have is how do i setup my vcm scanner to read my PLX wideband? i have an mpvi2 so do i need to use my prolink for that? or is there another way

Your post says you have a gen 3 ls, I'm assuming it's a P01 ecm, so search "EGR wideband" you can run the signal wire to the ecm through the egr sensor wire. If the egr wire isn't there, you can run a wire to the pcm. There are lots of forum posts detailing this process. You can log egr voltage with hptuners and make user math parameter to make if lamda/afr. This is how I log my Aem wideband with the scanner without the pro features.

[1988montecarloss]

Your post says you have a gen 3 ls, I'm assuming it's a P01 ecm, so search "EGR wideband" you can run the signal wire to the ecm through the egr sensor wire. If the egr wire isn't there, you can run a wire to the pcm. There are lots of forum posts detailing this process. You can log egr voltage with hptuners and make user math parameter to make if lamda/afr. This is how I log my Aem wideband with the scanner without the pro features.

yes it is a P01, i think thats actually how my previous tuner had it set up now that you say that, i will double check

its actually set up on the ac pressure sensor signal, assuming thats 0-5v as well and the process is the same?

[1988montecarloss]

i got my o2 and o2 error setup according to this video https://www.youtube.com/watch?v=Ru_2M2uGSKs&t=323s and can get my o2 to log accurately through the AC pressure sensor but the o2 error will not read no matter what i mess with

ive also got the idle dialed into stoich pretty well and car starts and idles great but surges anything over 1500ish rpm, whats causing the surge? too lean and VE table not smooth enough? i took a quick log driving up and down the driveway showing it that i attached

i messed with it and reflashed a couple times but i dont wanna go to far without getting my o2 error figured out

[danmw2003]

i got my o2 and o2 error setup according to this video https://www.youtube.com/watch?v=Ru_2M2uGSKs&t=323s and can get my o2 to log accurately through the AC pressure sensor but the o2 error will not read no matter what i mess with

ive also got the idle dialed into stoich pretty well and car starts and idles great but surges anything over 1500ish rpm, whats causing the surge? too lean and VE table not smooth enough? i took a quick log driving up and down the driveway showing it that i attached

i messed with it and reflashed a couple times but i dont wanna go to far without getting my o2 error figured out

Not that I can be of much help because I'm a noob myself, but I think you need to post your tune as well, for the more experienced people here to look at. Posting just your log doesnt help much.

[1988montecarloss]

Not that I can be of much help because I'm a noob myself, but I think you need to post your tune as well, for the more experienced people here to look at. Posting just your log doesnt help much.

ok here is the current tune and original tune on the smaller injectors as well, car ran good on the original tune with smaller injectors other than running out of fuel up top


update: i did get the o2 error working but cant figure out the problem with the car surging after 1800rpm or so, bucks pretty badly and reads lean no matter how much i change the VE table in that area going one way or the other

is my commanded air fuel table messed up? i havent touched that from the previous tune

[danmw2003]

Well I noticed your minimum injector pulse is lower than your default injector pulse. Also your short pulse adder and short pulse limit dont look right either. Did you get the injector data from the manufacturer? I know that stuff has to be spot on. But like I said, Im a noob so take what I say with a grain of salt. Im learning too

[danmw2003]

I dont think your short pulse limit should be 3.997ms either. That could be a large part of your problem. Really none of that injector data you have in there looks right to me. Hopefully a more knowledgeable person chimes in and takes a look at that.

[1988montecarloss]

I dont think your short pulse limit should be 3.997ms either. That could be a large part of your problem. Really none of that injector data you have in there looks right to me. Hopefully a more knowledgeable person chimes in and takes a look at that.

https://forum.hptuners.com/showthrea...-in-ls1-format

i got the injector data out of post #2 in this thread

what should the short pulse limit be? i dont see anything pertaining to that in that thread^^

now that i look at it though i think i mightve forgotten to save after changing the default injector pulse, i have set the minimum and the default to .6328 like listed in the link above

[danmw2003]

Looks like you got all the data in there correctly. Maybe just pull some fuel out of your whole VE table as 5FDP suggested and see where its at. Use LTFT data or a wideband

[1988montecarloss]

i pulled 10% out all over to start i will have to try it out tomorrow as its raining here now and the car has drag slicks and no windshield wipers

should i change the short pulse limit from 3.997? i cant find any other data for that online

[danmw2003]

I honestly dont know. I'd hate to give you bad advice

[Lakegoat]

If you are SD tuned, Go to DTC's and make P0101,102,103 Mil on First Error and uncheck the boxes.

[Lakegoat]

Take it out of open loop, turn off LTFT's and use STFT's to tune your normal drive around. You do have to use the correct injector data for your injectors. Get the part number and MFG and look up GM/HPTuners specs. Since this a swap vehicle, does it have a return style fuel system or just a dead head system?

[Matt Vardaman]

yes it is a P01, i think thats actually how my previous tuner had it set up now that you say that, i will double check

its actually set up on the ac pressure sensor signal, assuming thats 0-5v as well and the process is the same?

The process is the same. I have working A/C so I used the egr wiring when I removed the Egr.

[1988montecarloss]

Take it out of open loop, turn off LTFT's and use STFT's to tune your normal drive around. You do have to use the correct injector data for your injectors. Get the part number and MFG and look up GM/HPTuners specs. Since this a swap vehicle, does it have a return style fuel system or just a dead head system?

how do i take it out of open and turn off ltft? i think i have it set up as that but not entirely sure, i posted the tune file as well

injectors are oem 12613412 50lbers and i have put all the correct inj data in i believe, i have found a couple different sets of data but they were both very close and no change in how the car runs with either one

fuel system uses a corvette style regulator with intank walbro 255lph and single feed truck fuel rails