LTFT's are all zero above 4000 RPM !!

[Thedude]

Trying to get some sort of halfway reasonable SD tune done here using the LTFT's (no, I don't have a WB O2 yet)
But it seems no matter how light I try and be on the throttle, all my LTFT's seem to be lock at zero above 4000 RPM.
MAF is disconnected.
Seems like it must be going into PE mode, by I thought it was only supposed to do that at WOT ??
What am i doing wrong ??
( Duh stoopid )

[dfe1]

Could be any number of causes, but you're going to have to supply more information-- what have you changed in the current .tun file? If you re-enable the MAF, does the problem remain? Do MAP and MAF readings look reasonable? (Even in SD mode, the system displays a MAF reading (grams/second), it's just computed, rather than measured.)

[bK]

Could be that your commanded AFR is set to 14.63:1, NBO2 aren't that good at reading outside of this range hence the PCM goes into open loop.

[Thedude]

Mostly basic changes to my .tun file, such as raised rev. limiter, etc.
(I have 224/224/ .581/.581 112 LCA cam, Patriot stg.2 heads, headers, etc.)
I have: increased timing by about 4 deg., tapering off gradually until about .6 g/cyl. (makes the cam respond better on low RPM)
VE: decreased VE values (b1010 & b0103) by 2%@1600 RPM, 15%@1200, 18%@800, 20%@400RPM. Added 5% to whole rest of VE tables to keep from lean during SD tuning.
B4307: raised idle airflow +1 to improve idle for cam
B4603: raised idle speeds to 900 A/C on , 850, A/C off
AIR disabled, EGR disabled, CAT overtemp. protection disabled, P0101-p0103 set to "NO MIL"
B3601 (AFR): set to 14.63
(not sure what all info you need there, please let me know any other parameters you might need to know)
Problem is there with/without MAF connected.
MAF and MAP reading look reasonable, best I can tell.
I noticed with MAF disconnected, any of my MAPs that are plotted using CYLAIR (g/cyl) only have the .08 g/cyl. column filled, is that normal?

I noticed examining the data I have collected, that the LTFT's seem to be locking to zero when ever FTC cell 15 or 22 have been selected by the PCM...but they are being selected with TPS as low as 44%... I thought FTC 15 and 22 were for WOT situations ONLY????
man, I'm confused.

[Black02SS]

The car is going into Open Loop causing the LTFT's to show 0. It will almost always happen if the tune is close. The reason you are seeing some cells at 44% TPA like this is because the PE table is also done by TP angle. Only way to tune WOT is with a wideband or by looking at the narrowband o2 values.

Also, if you are using the default maps, then you need to change the header to reflect the Air Flow in Speed Density. You are only seeing .08 because you don't have the correct PID selected in the scanner causing the data to be plotted incorrectly.

[Thedude]

The car is going into Open Loop causing the LTFT's to show 0. It will almost always happen if the tune is close. The reason you are seeing some cells at 44% TPA like this is because the PE table is also done by TP angle. Only way to tune WOT is with a wideband or by looking at the narrowband o2 values.

Also, if you are using the default maps, then you need to change the header to reflect the Air Flow in Speed Density. You are only seeing .08 because you don't have the correct PID selected in the scanner causing the data to be plotted incorrectly.

Ok, I got the part about the Maps, I should have had GM.DYLCYLAIR -"AIRFLOW G/CYL - SPEED DENSITY" selected instead of CYLAIR - air mas per cylinder.
Now I see why it is so important to have a WB02.
Still, folks were tuning these cars a few years ago using the LTFT's... there's gotta be a way. Maybe not ??
I no longer have my stock MAF, and would like to just stay maff-less (SD).
EFILive is such a great product, if only I could get down how to make full use of it !

[Black02SS]

Shoot me a email at black02ss at gmail dot com and I'll try and help you get started.

[dfe1]

Now I see why it is so important to have a WB02.
Still, folks were tuning these cars a few years ago using the LTFT's... there's gotta be a way. Maybe not ??
I no longer have my stock MAF, and would like to just stay maff-less (SD).
EFILive is such a great product, if only I could get down how to make full use of it !

The best way to learn the program is to experiment with it. If you save each new file with a different name, you can always go back to a previous one if you get way off the mark. You can get really close with the narrow band O2 sensors by watching the LTFTs, but only when working with stoichiometric air/fuel ratios (14.63:1). Back in the day, we used to tune WOT air/fuel using the narrow band voltage readings, but that is completely hit and miss. Narrow band O2 sensors are designed to toggle as mixtures transition from richer to leaner (or vice versa) than stoichiometric. So even though voltage varies with air/fuel ratios, the variance is nowhere near linear. I once changed WOT air/fuel one full ratio (as recorded by a wide band) and the narrow band sensor readings only changed by 30 or 40 millivolts. Obviously, if you're going to tune WOT fuel you need a wide band, but you can dial in your part throttle and idle AFRs with the LTFT readings.