Thread: LTFT moving in open loop (O2 unplugged)??

So I've been playing around with tuning with the O2 unplugged in open loop with the wideband in its place. So I was doing a few scans and noticed the LtFTs moving. Thought they stayed at zero in open loop. What would be making them move??

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Bump ECT enable to max?

I don't see any ECT Enable but I'll keep looking

nope no ect enable.. ughh.. Any other way to get it to stay in open loop??

fuel -> open & closed loop -> coolant temp

assuming HPT.

If you dont see that, get the latest beta.

nope DHP so I'm probably screwed..again.. Do you know if you can change the injecter pulse width lower limit in hpt as well?? I'm have a problem with the larger injectors not allowing a low enough pulse width under decel but not in fuel cut off.

You can use TT to adjust min pulse width, however how are you hitting that? Do you have 100+ lb/hr injectors?

Are you saying you go rich in decell before DFCO?

Can't use tt because my osid isn't supported for whatever reason although I've been told that if the bin will open in dhp that it should open in TT but it doesn't.. I have 60lb injectors in the car.. when running e85 the min pulse width is fine but e10 under decel it goes rich.. not a huge deal but I would like to see if I can fix it if I can.

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Here's my osid if any one wants to try it on there TT. I could even send you the bin to try.. 12584058

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Thats the wrong osid for mine.. that was the neighbors i wrote down the other day.. I'll get mine in the morning after the first cup of coffee..


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DFCO is enabled no matter what your injectors want to do... If you decel it works fine. Also I have ran 60s on pump gas for years and years without any "rich on decel" conditions without modifying anything.

You can use TT to adjust min pulse width,

Minimum pulsewidth is a bit misleading... Its not minimum commanded, but it is actually your "minimum deadtime"... aka minimum injector voltage offset. The voltage offset table works with that table to determine minimum pulsewidths. There are some quirky tables that actually delegate what your minimums are when your pcm wants to violate that rule... and its not pretty.

So I was doing a few scans and noticed the LtFTs moving.

2 things.

1. for some reason the LTFT's will read crap randomly during warmup, cat testing (select 00+ files only), maf fail mode, among other things. I have never found them during normal driving, but it will show up alot during idle for me every now and then. It doesnt seem to effect anything.

2. The PCM seems to be very good at randomly remembering fuel trims from when it had closed loop. you have to clear them out a few times using the fuel trim clear command in DHP to lose all the ones in the fuel trim table.

Originally Posted by gtpsleeper

are you adjusting your fuel injectors for the switch from e85 to e10 and vise versa?

Yes, Just the IFR Table to switch between blends of fuels.. Right now I'm just "play tuning" learning the different ends and outs.. Mostly just on my drive back and forth to work.. I know with the same cal in the car and the same fuel it was a lot richer this morning (70degF) then it was on the way home last night (87degF). That's with Engine Upstream 02 unplugged and running the wideband.

Voltage offset is base offset, offset vs vacuum is short pulse adder and min pulse width is the mininum pulse width allowed after offset before fuel trims.

Calculate the required IPW based on dynair and offset in pcm. It works as its supposed to.


Dead time varries based on voltage and pressure across injector. There isnt one set value it uses all of the time.

Ok -- I downloaded the latest database for tiny tuner.. Reinstalled everything and now I can open my BIN.. Now it's more tuning to destroy... So what do I change to play with the min pulse width??

Originally Posted by matt5112

Voltage offset is base offset, offset vs vacuum is short pulse adder and min pulse width is the mininum pulse width allowed after offset before fuel trims.

Calculate the required IPW based on dynair and offset in pcm. It works as its supposed to.


Dead time varries based on voltage and pressure across injector. There isnt one set value it uses all of the time.

It doesn't work like that but OK.

Op. Don't mess with offsets on 60s... it doesn't work like it should.

I was just gonna see if I could get the dfco to come on a little sooner.. It seems to take forever.. I only mess with the ifr table to go back and forth from e85 to e10 and so forth. I'll play a little .. If I get messed Up I always have my barely modified stock bin to fall back on..

Originally Posted by darkhorizon

It doesn't work like that but OK.

Believe it or not, I'd need something more than your word on that.