ltft programming...

[ozorowsky]

the help file states "You do not want the engine to go into power enrichment mode, as this will turn off closed loop fuel." Does this mean that I should not floor the car at all during test runs? I'm sorry, but I have read EVERY SINGLE post on here, and LOTS on ls1tech.com and am still so lost.

[brh26]

Your car has settings that tell it when it should be in open loop or closed loop. Engine Coolant Temp is one that determines when it transistions from Open Loop to Closed Loop. Once in Closed Loop under part throttle it stays in Closed Loop. and the computer "learns." If you go WOT the PCM tells it to go Open Loop and it stops learning until it isn't at WOT ( for a car the settings might be 94%TPS to go into Open Loop and 94% TPS respectively to go back to Closed Loop). So once you back off from WOT your car goes back to Closed Loop and "learning" resumes. The LTFT's are therefore for part throttle operation. Ideally you want to get your part throttle LTFT's slightly negative so that when you do go WOT they read "0" which means no additional fuel being added. If you have achieved both criteria described above you have successfully tuned the part throttle aspect. You can then move onto the fun bit of doing Power Enrichment(WOT) and Spark Advance etc

[ozorowsky]

ok, so you can not just drive around at part throttle, do a few full throttle hits, some part throttle...

The reason I ask this because if you watch the histogram display different fields in the table change according to how you push on the gas from what Ive noticed. If it is floored, you are covering bottom right of table. If you are part throttle, you are covering top left. This looks to me like you could tune all at once. Or am I wrong?

[Magic_Chicken]

The VE Table Tuning how to in the Help file explains a lot about LTFT & STFT tuning.

[02Z0h6]

Hi guys, this is my first post. I have read the help file and am still a little confused. (oz, you definately aren't the only one). Basically, in order to try to fill as many ltft cells as possible you must keep below 94% throttle? Then you do a couple wide open runs to fill the two WOT cells? I don't mean to hijack your thread oz, I just feel we're kind of in the same boat. ??? Thanks, Chad.

[ozorowsky]

no prob O2, I read the replies as well. I spend all day reading this board at work.

[Magic_Chicken]

Hi guys, this is my first post. I have read the help file and am still a little confused. (oz, you definately aren't the only one). Basically, in order to try to fill as many ltft cells as possible you must keep below 94% throttle? Then you do a couple wide open runs to fill the two WOT cells? I don't mean to hijack your thread oz, I just feel we're kind of in the same boat. ??? Thanks, Chad.

The best way to get as much data as you can is to (even if you have an auto) drive in each gear, shift later than usual, drive up hills, drive with the brake on, just vary your driving/load conditions. WOT runs will do nothing for your LTFT data, as you are trying to get your LTFT's slightly negative so when you do go to WOT the LTFT's won't be stuck on a positive number which adds fuel and makes WOT tuning more difficult. Negative LTFT's will always go to 0 at WOT, and positive will generally stick with the number it was at right before WOT. Sorry if this confused you.

[ozorowsky]

Nope I understand a lot better now. So would -8 or -12 be bad? I have a few of those now, but NO positives.

[02Z0h6]

Thanks Magic and to oz for letting me in on your thread. I'll log some data tonight.