Question about mid and lo LTFT

[LTUDSM]

i was looking at my log today while i was idling,My STFT are bouncing between +2/-2%. LTFT lo are sitting right at 12.5% and not moving at all,i tried to mess with global fuel and injector deadtime to see any changes in LTFT lo ,but nutting changed. Then i saw,that the LTFT mid are sitting at 0 all the time,no matter if the car is idling or im driving. Does it supposed to be like that,or there is something going on more??? thanks for any suggestions..

 

[banishedmunk]

I suggest resetting the fuel trims via the ECU-> RESET FUEL TRIMS. then see if it goes back up.

have you verified that your maf comp tables are properly set along with global and deadtimes.

if you are running the stock maf you should use this method for the injectors with the maf comp sliders zeroed
1. Car must be fully warmed up then must be operated at cruise for about 10 minutes
followed by idle for 5 minutes to get stable LTFT values.
2. Compare the LTFT at idle and cruise. You want both to be right about zero (+/-
5% or so).
3. If the two are about the same, dead time setting is good.
4. If they are equal but non-zero, adjust the global setting.
5. If idle LTFT is more positive than cruise LTFT, increase the dead time, less,
decrease.

 

[LTUDSM]

I made two logs. one with adjusted mafcomp. another with mafcomp zeroed out.

with adjusted mafcomp -LTFT lo stays 12,5%
with mafcomp zeroed out- LTFT lo stays ~5%

Something is weird. I tried to get aiflowperrev to near .25gm/rev,but cars barely stays idling. when i make mafcomp sliders to zero.car idles much better and LTFT lo drops to near 5%.

 

[LTUDSM]

Ok,i just figure out why im getting high airflow into the engine-The reason is ,because of BC 272'S. So i wasn't adjusting MafComp sliders alot,but was dealing with the fuel adjustments to get my fueltrims close to zero. So i got a new log with my idle tune and i want someone to confirm,that is correct

 

[T is for TURBO]

I can't look at your log as I'm at work, however cams shouldn't affect airflowperrev. You should still strive for ~.25 unless your have a stroker or auto, then aim higher.

also, there is an easier way to dial in your idle. Fom ECMLinks wiki

I generally monitor CombinedFT and AirflowPerRev at idle. I want to see CombinedFT cycling around +/- 8% or so.

You'd expect to see 0.24-0.28 g/rev for AirflowPerRev at idle 1), but I don't get too caught up on that if the fuel trim is inline and global fuel settings make sense for the injectors that are installed.

If fuel trim at idle is not where I want it, I either use the lower airflow sliders (log MAFRaw to see where to make adjustments) or I use deadtime to tweak things. If I'm running SD, I'll use the SD VE table instead of the airflow sliders.

Whether I make changes to airflow or deadtime usually depends on whether AirflowPerRev is inline or not. If AirflowPerRev is off from the expected value in the opposite direction from CombinedFT, then I adjust the lower airflow sliders more than deadtime.

If AirflowPerRev is around what I'd expect, I might focus on deadtime instead for idle fuel trim adjustments. Just keep an ear out for little misfires at idle that can sometimes be introduced with deadtime adjustments, particularly if the injectors are not well matched at low pulsewidth.

Also, go HERE
And watch this demo.

 

[LTUDSM]

I can't look at your log as I'm at work, however cams shouldn't affect airflowperrev. You should still strive for ~.25 unless your have a stroker or auto, then aim higher.

also, there is an easier way to dial in your idle. Fom ECMLinks wiki

I generally monitor CombinedFT and AirflowPerRev at idle. I want to see CombinedFT cycling around +/- 8% or so.

You'd expect to see 0.24-0.28 g/rev for AirflowPerRev at idle 1), but I don't get too caught up on that if the fuel trim is inline and global fuel settings make sense for the injectors that are installed.

If fuel trim at idle is not where I want it, I either use the lower airflow sliders (log MAFRaw to see where to make adjustments) or I use deadtime to tweak things. If I'm running SD, I'll use the SD VE table instead of the airflow sliders.

Whether I make changes to airflow or deadtime usually depends on whether AirflowPerRev is inline or not. If AirflowPerRev is off from the expected value in the opposite direction from CombinedFT, then I adjust the lower airflow sliders more than deadtime.

If AirflowPerRev is around what I'd expect, I might focus on deadtime instead for idle fuel trim adjustments. Just keep an ear out for little misfires at idle that can sometimes be introduced with deadtime adjustments, particularly if the injectors are not well matched at low pulsewidth.

Also, go HERE
And watch this demo.

I talked to Dave from ecmlink and he said,tha cams coud cause the higher airflow.Because when i try to get .25gm/rev,my car just barely idles and rpms drops to 600.and ft are out of wack.So he suggested me to keep my airflow at the point where my fueltrims are getting close to 0%

 

[T is for TURBO]

I talked to Dave from ecmlink and he said,tha cams coud cause the higher airflow.Because when i try to get .25gm/rev,my car just barely idles and rpms drops to 600.and ft are out of wack.So he suggested me to keep my airflow at the point where my fueltrims are getting close to 0%

Hmmm... Now that you mention is, I do recall someone saying the BC *I THINK* 280 cams were giving a weird airflowperrev. I didn't think 272 would be enough of to cause a difference, especially since my 272 (HKS) seem to run perfectly at .25g/rev. I guess you learn something new everyday.

Quick qustions, have you ajdusted your ISCposition to 30?

 

[LTUDSM]

Hmmm... Now that you mention is, I do recall someone saying the BC *I THINK* 280 cams were giving a weird airflowperrev. I didn't think 272 would be enough of to cause a difference, especially since my 272 (HKS) seem to run perfectly at .25g/rev. I guess you learn something new everyday.

Quick qustions, have you ajdusted your ISCposition to 30?

yes i did.Its not of the cams it self,i got a ported head,oversized valves,SMIM and fp red turbo,that are making my high airflow

 

[Imback]

I'm able to have my airflowperrev at .25 and i have 280's as well

You need to raise your idle then adjust the maf comp sliders

 

[LTUDSM]

I'm able to have my airflowperrev at .25 and i have 280's as well

You need to raise your idle then adjust the maf comp sliders

wht rpms youre idling?

 

[Imback]

1050

 

[LTUDSM]

1050

so in my case,if im, running 272's instead 800 rpms i need to raise to like 950-1000 right?

 

[Imback]

Yep. Try 1000 then start bring down the 0 and 50htz slider

 

[LTUDSM]

so what is the perfect way to set up the rpms??! im doing like that:

setting up the idle rpm range in an ecmlink,then adjusting the biss till my Iscposition shows the value of 30 right?

 

[T is for TURBO]

so what is the perfect way to set up the rpms??! im doing like that:

setting up the idle rpm range in an ecmlink,then adjusting the biss till my Iscposition shows the value of 30 right?

Correct. HVAC fans off, lights off, A/C off. Aim for about 30 and you should be good to go. Remember that the car should be at operating temp, and that the ISC position changes a little bit as the radiator fan kicks on and off. I try to set it while the fan is off. I have an ISC position that hovers between 28 and 32 with the fan off. When the fan kicks in it's a little higher, 31-35.

Edit: This is assuming that you don't have any boost leaks.

 

[LTUDSM]

Correct. HVAC fans off, lights off, A/C off. Aim for about 30 and you should be good to go. Remember that the car should be at operating temp, and that the ISC position changes a little bit as the radiator fan kicks on and off. I try to set it while the fan is off. I have an ISC position that hovers between 28 and 32 with the fan off. When the fan kicks in it's a little higher, 31-35.

Edit: This is assuming that you don't have any boost leaks.

Yes i dont have any boost leaks.Recently changed the tb gaskets,tb shaft seals,Msade a custom one peace uicp,(no more extra couplers) same thing with the lower ic pipe.cleaned the vac lines,left only for a AFPR,bov,mbc and wastegate. So made my life easier to detect a boost leaks DD


Ok back on topic. I raised my idle to 1000 rpms. Adjusted the biss,so IscPosition is at 30 without any accessories running and fans off. Tried adjusting the 0 and 50hz sliders under MafComp to get my fuel trims to 0% and to get AirflowPerev to .25mg/rev.When i did that,my fuel trims got out ow wack. Ican get STFT and CombinedFt close to 0%.STFT lowest i could get is 12.7% with adding 170 deadtime on top of the suggested value of 320.the CombinedFt stays at 18.4-17.6%.LTFT lo stays at 7.6%. What a hell is going on??!!!
When i had my mafcomp slider at 0 i could get STFT, CombinedFt,LTFT lo to +/- 1.2% at 800 rpm targeted idle. With the Mafcomp sliders adjusted and Airflowperev could reads .25gm/rev and rpm raised to 1k,the car idles rough and i could smell gas from the tailpipe while idling due rich FT.
Im thinking to go back to where i was with my previous log and call it a day,because at that point the car was performing great on a low throttle.

 

[T is for TURBO]

Well, .25 Airflowperrev is just a sanity check, so don't beat your brains out trying to hit that target. If your CombinedFT is near zero, your dead time looks okay, it's idleing nice, you have no boost leaks, your fuel pressure is correct, and your global fuel is set properly, I would say that a higher Airflowperrev is okay, (within reason).

When you have your MAFcomp sliders zeroed out, where does Airflowperrev sit?

 

[LTUDSM]

Well, .25 Airflowperrev is just a sanity check, so don't beat your brains out trying to hit that target. If your CombinedFT is near zero, your dead time looks okay, it's idleing nice, you have no boost leaks, your fuel pressure is correct, and your global fuel is set properly, I would say that a higher Airflowperrev is okay, (within reason).

When you have your MAFcomp sliders zeroed out, where does Airflowperrev sit?

This is how my idle looks like right now: 28-30 gm/rev,iscposition 30,STFT +/-1%,CombinedFt +/-1.5%,LTFT 0.8- /-0.5% Wideband reads 14:3-14:7,idle set at 900 rpms Thats the numbers i got after 1.5 hour of adjusting everything.... So i guess im ready for a cruise tune right?

 

[T is for TURBO]

This is how my idle looks like right now: 28-30 gm/rev,iscposition 30,STFT +/-1%,CombinedFt +/-1.5%,LTFT 0.8- /-0.5% Wideband reads 14:3-14:7,idle set at 900 rpms Thats the numbers i got after 1.5 hour of adjusting everything.... So i guess im ready for a cruise tune right?

I'd be happy with those numbers

Are you using the stock MAF?

 

[LTUDSM]

I'd be happy with those numbers

Are you using the stock MAF?

Yes,im on a stock2g maf.But i got an adapter 4in. and FP 4in intake pipe (ceramic coated)