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Fueltrims?

3835 Views 16 Replies 3 Participants Last post by  turbolarry
Didnt see this on these forums anywhere, so. Just wondering, i put larger injectors in. So using the tuning guide on these forums, i decreased fuel in low and high. So now im trying to get the fuel trims to 0%. Anyone know about how long does this take? I was sitting there for awhile they didnt seem to change much. Even after i increased fuel at idel. Thanks for any input.
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Where are your fuel trims at and the corresponding RPMS?
Try and get them as close to 0 as you can. +/-3 is perfectly fine. After logging and tuning a couple of Evo's I might change it to +/-5 which is OK too.
It took mine car a full three days (maybe four) for LTFT's to settle at 0% at 3000 RPMS. I'm +/-3 everywere else.
You just don't want things so far out of wack that the ECU can't do it's job
Ok, i reset the ecu. I think that had something to do with it. But im running 780 injectors, 280 cams turbo kit all the other stuff. In order for me to get the ST to near 0 i had to add fuel into the positive range. In the setup i followed base adjustments for 780s is -36 in all rpm ranges. So now if i follow these settings for 0 ST/ LTFT i think is like 16% pos. in all hi/lo ranges i wont be able to get any timing. This just dosent sound right to me. I mean 780s are pretty frekin big. to have to add that much fuel? Sounds crazy. But i tried a WOT in3rd and its getting way to much fuel. Stumbeling stutering. Even at idel u can smell un burnt fuel, u should see my bumper. Maybe ill reset the ecu again and start at the recommended750 or 720 injector setup. Any input? thanks
Last week I did some initial setup for a friend running 720's. In the low throttle I had to richen it up like 35% at 1000-3000 RPM's. I think this has more to do with aftermarket intakes.
Don't carry your low numbers to high throttle. Keep the base setting of -36% in high throttle.
Thanks, I was thinkin the same thing. Maybe low throttle has something to do with the overlap of the cams, with needing the extra fuel. I have an RNR 50 trim kit. I think i'll start with around 13psi and go from there with hi/ settings. See how it goes 2morrow. I think my lo/ settings are around +16 or 17. Its tough to get those ST fueltrims at 0% since they move around so quick. They range frm +5 to -5 in lo setting at each rpm, is that good enough to get 0% LT?
evolved4g63 said:
They range frm +5 to -5 in lo setting at each rpm, is that good enough to get 0% LT?
That's good enough. From there the ECU can do it's job. Give it a day of driving and see if anything changes.
Well finally got my log viewer to work on the PC. Im wondering if i should be seeing a drop in timing at 4500rpms? Its at 14, then after 4500 it increases nicley to 21 at about 6750. O2 is .92-.94. How it is now im running 15.5 psi. As long as that dip is normal "i thought i read somwhere that it is" I would like to keep tunning to the stock turbo boost of 19psi. All on 94 sunoco. Then when the alky kit comes tune it some more. BTW, props to turbolarry for all the help. Oh yeah, at 15.5 this car is sick. I had my girlfriend hitting the go and stop button on the logger today. Of the 2 runs i had time for today, she said she never got pushed back into the seat like that before.
evolved4g63 said:
Well finally got my log viewer to work on the PC. Im wondering if i should be seeing a drop in timing at 4500rpms? Its at 14, then after 4500 it increases nicley to 21 at about 6750. O2 is .92-.94. How it is now im running 15.5 psi. As long as that dip is normal "i thought i read somwhere that it is" I would like to keep tunning to the stock turbo boost of 19psi. All on 94 sunoco. Then when the alky kit comes tune it some more. BTW, props to turbolarry for all the help. Oh yeah, at 15.5 this car is sick. I had my girlfriend hitting the go and stop button on the logger today. Of the 2 runs i had time for today, she said she never got pushed back into the seat like that before.

Only as boost starts to build should there be a pull in timing. After that, as long as there is no knock, the ECU will advance it. When does full boost hit on that 50 trim?
The .92-.94 O2 voltage is mainly for 91 octane (all I get in CA :mad: ). Lean it out a little more, or raise the boost a little, and watch for knock/pulled timing up top. You could probably get away with .91v on the 94 octane.
Actually full boost is prolly right around 4500. i'll make sure today. The timing just keeps climbing after 4500. Will post some results later.
Yeah full boost hits like right at 4500. Almost exactly, the external w/g opens at 4500. Anyway, if i were to see a fall in timing anywhere else i would just add a couple % of fuel to the equation correct? Just makin sure. When i first got my SAFC, it was 2 years ago and came with the Buschur settings so i just set it and left it. Never really messed with it untill lately. Thanks for all the help.
evolved4g63 said:
Yeah full boost hits like right at 4500. Almost exactly, the external w/g opens at 4500. Anyway, if i were to see a fall in timing anywhere else i would just add a couple % of fuel to the equation correct? Just makin sure. When i first got my SAFC, it was 2 years ago and came with the Buschur settings so i just set it and left it. Never really messed with it untill lately. Thanks for all the help.

Wow, 4500. I've never ran anything bigger than stock (BT-28 in the Eclipse) so I know nothing about turbo lag. Is that with a large exhaust housing, or regular thrust bearing?
Any other dips in timing (as long as it's not rich knock) add 1-2%
Yeah its a thrust bearing. Dry cartridge. Its not mydaily driver, so it dosent matter to me much. Maybe some time ill give the BB turbo a shot. Or maybe the buschur 20/21g. But this thing has alot of headroom so . Is there a way to tell if its rich knock? Also in the lower RPMs in my 3rd gear pulls my O2 volts are like .88 is that safe? This is before and during spool.
Rich knock you'll see some thing like .96v and have a pull in timing.
.88v is lean, even on 94 octane. Rchen up the lower RPM's a little so you have steady voltage through out the pull.
This is off topic from my original post, just 2 let u know. Right now i am using an SAFC1. I am wondering if the wiring for an afc2 is different? Also will the harness that comes with the SAFC2 plug right into the harness that came with the 1 and is already hooked up to my ecu harness? With out moving wires around. Thanks
:(
The harnesses are not compadable. I wish they were.
turbolarry said:
Where are your fuel trims at and the corresponding RPMS?
Try and get them as close to 0 as you can. +/-3 is perfectly fine. After logging and tuning a couple of Evo's I might change it to +/-5 which is OK too.
It took mine car a full three days (maybe four) for LTFT's to settle at 0% at 3000 RPMS. I'm +/-3 everywere else.
You just don't want things so far out of wack that the ECU can't do it's job

When setting the low fuel trims does the car need to be under load? My seems to be acting strange. I reset the battery and when I try to set the 1000 RPM point, I have to go down to 0 on my S-AFC II to get the STFT to 0. I have 680cc injectors. Same with the higher RPM's? I am doing this while the car is not under load.
sccavee said:
When setting the low fuel trims does the car need to be under load? My seems to be acting strange. I reset the battery and when I try to set the 1000 RPM point, I have to go down to 0 on my S-AFC II to get the STFT to 0. I have 680cc injectors. Same with the higher RPM's? I am doing this while the car is not under load.
Do you mean low throttle correction?
No. No load.
Try it first at idle. Rev and hold the RPM point. STFT's are going to fuxuate and as long as the LTFT's are with in +/-5 (as close to 0 as you can get) it's alright. Do this to 4000 RPMS.
Then watch the FT's while cruising a flat road/minimal load at the same RPM points. Make adjustments as you need it.
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