60lb/hr injector ltft problems

[ZombieSS]

well, i'm having issues getting my 60/lb injectors tuned right. I've got them idling with o2's switching back and forth by tweaking the offset table to lean them out in the areas where the ecu is commanding too long of a pulse width.

My main problem is after getting the whole car to basically run at 14.7:1 (logged on wideband) and drive really nice, my LTFT's have gone to crap. They are all +10 now and no change to the IFR table will compensate for it.

Is there a problem if I just turn off the LTFT's? It's about the only issues i have left on the tune and i'm starting to get frustrated with getting them negative on these injectors. What effects will running without ltft enabled have?

i'm thinking that my problem is being caused by poor o2 switching. When the car is run really rich and the o2's hang positive the LTFT's go negative.

[BLOWNZ06]

I think you have gone about tuning for injectors all wrong.

With no other changes to he vehicle the ONLY change you should have to make is to the IFR table. I then scale the MAF to bring the LTFT's back into line if it is necessary.

There are come complicated methods for adjusting for injectors.. when I went from 28 to 42# inj. I just multiplied the IFR table by 1.5 and did not have to touch anything else for the LTFT's to stay in line.

Just remember the IFR table is univeral.. so a change to it will change everything else automatically. I would at least try my method. Go back the program you had before you started messing with it, try my method. You did save your program before you started making changes right? Lesson #1

Hope that helps.

[ZombieSS]

I think you have gone about tuning for injectors all wrong.

With no other changes to he vehicle the ONLY change you should have to make is to the IFR table. I then scale the MAF to bring the LTFT's back into line if it is necessary.

There are come complicated methods for adjusting for injectors.. when I went from 28 to 42# inj. I just multiplied the IFR table by 1.5 and did not have to touch anything else for the LTFT's to stay in line.

Just remember the IFR table is univeral.. so a change to it will change everything else automatically. I would at least try my method. Go back the program you had before you started messing with it, try my method. You did save your program before you started making changes right? Lesson #1

Hope that helps.

I have tried just modding the IFR table and it just doesnt work very well at all. Everyone running these on stock sized motors complains of them being rich down low at idle. My 42's were a non issue, but 60's are just a wee bit big. I've tuned 30+ ls1's, but none have ever had an issue like this.

I'm also very against scaling the maf table unless the maf has changed in some way. Too many calculations rely on the maf for me to change it.

I don't like making the changes with the offset table because thats not what it's supposed to be used for, but it works really really good.


Been driving with LTFT's off now, car runs a bit smoother

[MNR-0]

The car shoud run in closed loop at idle and low throttle. I would look at reducing your fuel charge via your O2 error gain tables and perhaps raising the IFRs a frag. under 50kPa to lean it off. Thats what I did - built my own IFR table based off the observed LTFT in the histogram. Adjusting the O2 switchpoints lower can also lean it off at part throttle. Things to play with anyway.

[ZombieSS]

Funny you should mention that because it's exactly what I am attempting to accomplish right now

Working on getting my o2's in line.

[redhardsupra]

not to hijack or anything, but what's the philosophy behind changing O2 switching points?

[MNR-0]

You can control the AFR in closed loop from 14.2-15.2 by adjusting the O2 switch points in millivolts. If you want it leaner then reduce the numbers.

[redhardsupra]

i can't find it where are these O2 switchpoints set?

[MNR-0]

Open and Closed Loop Rich Lean vs Airflow

[redhardsupra]

Hmm...my O2's are consistently 20mV higher on one bank than the other. So would this be a good place to make them oscillate more 'together'? Or is that a bad idea?

[MNR-0]

Hmm...my O2's are consistently 20mV higher on one bank than the other. So would this be a good place to make them oscillate more 'together'? Or is that a bad idea?

From what? The scanner? The bin file?

[redhardsupra]

no no, they're 20mV from each other, especially at WOT. old ones did it, now new ones did it. that makes me think that's just the nature of exhaust. should i leave it alone, or should i try to correct it?