Hey all. I am having a small battle with fuel trims on an LS1. I have installed a flex fuel sensor on the car its verified to be working and reading. However the fuel trims do not change even if the commanded afr changed. is there a blend setting I am missing somewhere? I have attached tune and log file. Thank you
If you are changing commanded AFR then it’s open loop and fuel trims are disabled! What OS are you using?
Email Tunes, [email protected]
96 TA Blown/Stroked, 4L80E/Fab 9
15 C7 A8 H/C 2.3 Blower/PI
14 Gen 5 Viper
Custom Mid Engine chassis, AKA GalBen C
I was saying I can see commanded afr changes as alcohol content increases. I do not see the injector duty cycle or injector time change. I do have the PCM set to open loop.
If you have it in Open loop fuel trims aren’t going to update..
If the stoich table is set properly the commander Stoich will match that of alcohol level
Email Tunes, [email protected]
96 TA Blown/Stroked, 4L80E/Fab 9
15 C7 A8 H/C 2.3 Blower/PI
14 Gen 5 Viper
Custom Mid Engine chassis, AKA GalBen C
Like he said yes....you will never see LTFT or STFT running open loop--that's the definition of open loop, no real time fueling corrections.
The changing commanded AFR is the correction for ethanol content.
When commanded AFR is updated, it will affect commanded pw etc. Maybe just not a significant enough increase to see at small idle PWs etc.
I understand the fuel trims not being present. I am referring to the Inj PW. if on Pump the stoich is 14.6AFR and on 40%E it moves to 12.4AFR and the sensor notices that change the PCM should then increase injector PW to achieve that target. With the increased E content the Inj DC or INJ PW does not change. on pump it was 1.7MS and on E40 it was 1.7. if I am looking at this wrong let me know. As I had to basically retune the Maf curve for E. Everything else I have tuned has a scalar for different E blends. I do not see it on this PCM. Thank You.Originally Posted by aaronc7
Excuse my curiosity but this seemed intersting how exactly were you able to do this on a gen 3 since gen3 don't have these flex fuel parameters on hp tuners I know you can install flex fuel sensor but you just don't have that flex fuel tabs like in spark ...etc or maybe your using a gen 4 or 5 pcm?
The 2002 Tahoe has flex fuel capabilities. check the calibration that I posted. the P01 out of tahoe has os 12216125. this one is flex fuel tables for spark and fuel stoich.
Lol I didn't pay attention my bad so some of the gen 3 pcms do have the flex fuel capabilities.
Amazing to think that an almost 20 years old pcm was cabable of doing this.
Got out of topic here sorry
I am no expert but did you change your injectors ?if so you need to insert your new injectors data
yeah the P01 and P59 I know are the ones that can support it. Injector data is updated. I used the data from the ID spreadsheet. ID1050x
Last edited by jsfrederick2011; 10-21-2020 at 04:43 PM. Reason: missed some information
anyone???
You won't see much of a change in Inj PW at an idle in this application. It's a 5.7L engine with 117 lb/hr injectors. In order to see the injector PW change as Alc %/Lambda changes, you'll need to pick out a spot with much higher airflow. Maybe take a look at PW at 5000 Hz with a commanded lambda of 14.7, then check the PW at 5000 Hz with a commanded lambda of 9.8. You'll notice a more substantial difference at that point.
thank you.... i just retuned on pump and called it good.
Reply With Quote