tuning VE, question about disconnecting maf

[Turo]

ok so i am trying to follow the writeup for tuning LTFT by unplugging the maf...



i followed the steps listed: disabled the SES light for codes p0101 p0102 p0103, copied the high octane table to the low octane, flashed the pcm with the new tune, unplugged the maf and started the car up to go do some logging. one problem though, with this setup my service vehicle light comes on (NOT the SES light), but if i plug the maf back in and upload the older tune the light goes away. will this affect my logs for tuning the VE table? i did a search but i haven't found any posts about a service vehicle light coming on after disconnecting the maf. thanks for any input.

[Turo]

nevermind, i went another way. instead of disconnecting the MAF, i put everything back and just set the maf fail frequency value to zero (this should put me to SD mode). 8)

[ozorowsky]

Does that actually put in SD mode? If so I'll add to my writeup thanks.

[Turo]

Does that actually put in SD mode? If so I'll add to my writeup thanks.

according to the guys on ls1tech it does. anyone else tried this? is there any way to know for sure that i am in SD mode?

[Magic_Chicken]

When I unplugged my MAF I was able to get my AFR down to 13:1, but then when I plugged my MAF back and put the fail frequency to 0, my AFR went back up to 14.7:1. I would have to guess mine is no longer in SD mode even though my truck is throwing MAF codes.

[Turo]

When I unplugged my MAF I was able to get my AFR down to 13:1, but then when I plugged my MAF back and put the fail frequency to 0, my AFR went back up to 14.7:1. I would have to guess mine is no longer in SD mode even though my truck is throwing MAF codes.

really? hmm, i guess the ls1tech guys might be mistaken. anyone else tried this?

[Magic_Chicken]

I forgot HP Tuners can control Closed Loop from the scanner, I went and turned off Closed Loop and my AFR went back to 13:1 range. HPT Rocks.

[BQuicksilver]

I forgot HP Tuners can control Closed Loop from the scanner, I went and turned off Closed Loop and my AFR went back to 13:1 range. HPT Rocks.

So instead of unplugging the MAF, shutting off the codes, etc can I just go into the VCM controls on the scanner and shut off closed loop mode for LTFT tuning? Or am I completely confused since LTFT tuning IS closed-loop tuning?

[CAUGHTU]

I agree with BQuickSilver, this post has competely confused me. Which way should you go. Unplug the MAF and diable the codes, leave the MAF plugged set the MAF Fail Frequency to 0, leave the MAF plugged and shut off Closed Loop?

[tomaSS]

Just unplug the MAF and forget about the code. So you have a check engine light on, big deal. At least you know its actually disabled. That's what I did, because I too was confused. This worked for me.

[BQuicksilver]

I agree with BQuickSilver, this post has competely confused me. Which way should you go. Unplug the MAF and diable the codes, leave the MAF plugged set the MAF Fail Frequency to 0, leave the MAF plugged and shut off Closed Loop?

CAUGHTU, assuming the F-Bods work the same, I just set the MAF fail frequency to "0" and started tuning...it works and seems the easiest. The DIC on the C5's will say "service engine soon" evene if you select to disable the MIL light.

[CAUGHTU]

Thanks, I will give it a try with both to see which works the best. What can I say I must have to much time on my hands, or too long of a drive into work. I can get a pretty good log with my 26 mile drive to work and another log going home. I will let you know which I like or if there is a difference.

Also if the LTFT is used to correct VE with the MAF unplugged, is this correcting the VE for when the car goes to WOT and PE mode, or is that a whole different animal?
Once the MAF is plugged back in (or Fail Frequency changed back to 13500 and the SES light should go out) how is the MAF variable effecting the VE table? Will it just run with the corrected VE table creating the better tune, or should the MAF remain unplug so that the MAF variable is never used with the corrected VE table?
Last mind bender, if the MAF is stock and the frequencies can be trusted for air flow amounts I could see where the corrected VE through the LTFT tuning technic would work well with a reattached MAF, but in the event that the stock MAF has been ported/polished/desceened/replaced and the frequencies are no longer accurate, in that event would it be better to set the VE table and forget about the reconnect.
;D

[BQuicksilver]

You're asking better questions, looks like you're picking it up quicker than most.

Those are big questions to answer, and I think at your stage I would read the stickies in the V8 tuning and newbie sections here, then read the stickies at LS1Tech.com in the PCM section. You'll benefit greatly from that, and should have the questions answered and a good idea of the general tuning concepts.

[CAUGHTU]

Thanks BQuickSilver, I will look into those, so much to learn so little time, but having fun, this is some very interesting stuff, and finally able to apply my computer knowledge to a server with 4 wheels.