ltfc

alpinestarr8 · Post by **alpinestarr8** » Tue Feb 27, 2007 1:13 pm

mike , this is chad from bakersfield, ca. ,ok i got ltfc down to 0.00% at wot in tow haul mode, so will this be ok for everyday driving? just driving around seening on a average 6.85% ltfc and also the engine seems to be running alot cooler @ 185 degrees will that mess with any other sensors?

Post by **06MonteSS** » Tue Feb 27, 2007 2:24 pm

actually, you want to monitor your LTFT's at cruise (driving around) and get THOSE to be around zero - usually people shoot for -2 to +2 or even -4 to +4.

If you're consistently getting +6.85 at driving/cruising around, you can do better. You can set the injector slope to -5% to bring those down and that should get you right in line.

After making that adjustment, drive around for a couple days (or about 50-100 miles) and then do a couple more logs to check it out again to see where the LTFT numbers are now.

Doing that should get you a little quicker throttle response, a little better mileage, and still lock in at 0 (or slightly negative) when you go WOT.

Post by **mikel** » Tue Feb 27, 2007 2:58 pm

Like he said.....^^^

Thanks Lew....

Post by **06MonteSS** » Tue Feb 27, 2007 3:07 pm

yeah baby!!! I think I'm ready for that CMR Single User software!!! LOL

no prob!

debo4x4 · Post by **debo4x4** » Tue Feb 27, 2007 4:47 pm

Should you also lean or richen out the fuel tables like this says? Would that be the WOT fuel setting?

Positive long term fuel trims For a positive value you subtract that value in percent in the predator injector slope. It is also recommended to lean both fuel tables by the same percentage.
Negative long term fuel trims For a negative value you add that value in percent in the predator injector slope. It is also recommended to richen both fuel tables by that same percentage.

alpinestarr8 · Post by **alpinestarr8** » Tue Feb 27, 2007 5:02 pm

thanks for the tid bit lew went out and palyed some more a +2.07 driving around -0.78 at wot ,she is a rocket. haha but really thanks alot for the info. talk to you guys later

Post by **06MonteSS** » Tue Feb 27, 2007 5:15 pm

most people find that if you go negative on inj. slope, you will need to go positive in the WOT/PE fuel table in both RPM ranges - and vice versa.

for instance, on my car right now, I have -5% injector slope and +3% (richer) in the WOT/PE rpm ranges. You can't get an accurate AFR reading without a wideband, but to get in the general safe zone, monitor your front (pre-cat) O2 sensors and you want them to be reading .88x - .910 at WOT. they should be bank 1 sensor 1, and bank 2 sensor 1 in the real time data section.

Alipne - you're welcome!!! keep those settings for a couple days and do another log and see where they've settled in at... and if the numbers still stay the same, you're there!

debo4x4 · Post by **debo4x4** » Tue Feb 27, 2007 5:36 pm

OK...so right now both my LTFT banks are in the -4 to -5 range during normal 55mph cruise. The O2 bank1 sensors are both showing between .845-.875 at WOT. I also get no knock retard at WOT. What adjustments do you recommend I make?

Post by **06MonteSS** » Wed Feb 28, 2007 9:40 am

if your ltft's are consistently at -4 to -5, the first thing I would do is just change the injector slope to +4%. Drive around for a while and do a log to see where the ltft's settle in at and see where the O2 voltage is. THEN go in to the WOT/PE RPM ranges and adjust those as needed - you may actually have to go positive for PE as well, since going positive for injector slope tells the ECM that the injectors are bigger and to spray LESS fuel, so you may need to add that fuel back and go +5 for the PE ranges.

See, for me it was the opposite - after adding my CAI, I was running lean (+7 ltft) - so when I went negative on injector slope, that tells my ECM that the injectors are smaller and to spray MORE fuel.

But, like I said, change the slope to +4% first, check the ltft's and O2 readings in a log, and then go in and adjust the PE ranges.

alpinestarr8 · Post by **alpinestarr8** » Wed Feb 28, 2007 4:39 pm

well for my numbers i am -5% on the injector slope and -10% on the wotf does that seem about right? +2.38 driving around at 60mph -1.73 at wot in tow haul mode.

johan · Post by **johan** » Wed Feb 28, 2007 4:41 pm

What other mods do you have done to the truck?

alpinestarr8 · Post by **alpinestarr8** » Wed Feb 28, 2007 5:36 pm

long tube headers, no cats ,air raid intake, granatlli maf, ls6 cam roller everthing aftermaket,msd ignition,e3 plugs,410 gears with a eaton possy,no mech fan two eletric fans, and no ac belt on durning winter , haha and royal purple all the way through

johan · Post by **johan** » Wed Feb 28, 2007 5:43 pm

I have seen aftermarket maf's cause issues with the trim readings before, I would suggest putting the stock maf back and see if the values look better. Whenever the trims do not go to zero at wot there is something else going on there. Some aftermarket maf's are calibrated to lean out your vehicle to gain performance by scewing the output signal going to pcm to read less air is entering the maf thus resulting in a leaner mixture. When you use a programmer of any sort it is vital that this data is not scewed as many parameters depend on this data to calculate where it needs to go in the calibration tables.
I would suggest trying this first and see how your numbers look.

alpinestarr8 · Post by **alpinestarr8** » Wed Feb 28, 2007 5:48 pm

ok i will try , it does make alot of sense that is all a maf does is tries to lean it out so the two maf, and the turner are fighting each other then correct?

johan · Post by **johan** » Wed Feb 28, 2007 6:05 pm

Yes well since both lean your vehicle out by different means you might actually damage something by running too lean.

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