tuning assitance, 15gs, 550s, chrome ecu

so just my update

fuel trims are not logging, no way, no how, tried differnt o2 sensors, maybe something is hard wired incorrectly...

at idle, the nbo2s are cycling, the wideband is showing 14.5-14.8 afrs at idle/cruise


i tried playing with the values at 1600mhz lowering the ve, i went down 1 point at a time until reaching 101, (started at 106). at 101, the afrs stopped dropping at 11.0. i also had to smooth the effect from the previous 3 cells to keep it from dipping below 11 before staying there. the car was still flooding as it bogged heavy and misfired a bit after shifting.


ive reset everything again, bumped the boost back down to WG pressure. it runs great, at 7psi...

i think i need to get my fuel trims working...before i start boosting more.

in in nj, a few minutes out of NYC....any recommendations id like to go somewhere to get tuned.

As said before the fuel trims aren't used at WOT. That is the open loop region. If you want to lean it at WOT then you lower the VE at 1600 Hz like you're doing. You probably shouldn't go much above 11 AFR though if you're on gas.

As far as closed loop goes, just run the car in your driveway and log the O2 sensors and the low trims. The low trims should adjust once every 4 minutes. Check that your O2 sensors are cycling.

If the low trims peg at +12.5 then you need to lower VE below 100 Hz. If they peg at -12.5 then you need to raise VE below 100 Hz. Don't bother looking at the trims at WOT.

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Originally Posted by Jimvr4

As said before the fuel trims aren't used at WOT. That is the open loop region. If you want to lean it at WOT then you lower the VE at 1600 Hz like you're doing. You probably shouldn't go much above 11 AFR though if you're on gas.

As far as closed loop goes, just run the car in your driveway and log the O2 sensors and the low trims. The low trims should adjust once every 4 minutes. Check that your O2 sensors are cycling.

If the low trims peg at +12.5 then you need to lower VE below 100 Hz. If they peg at -12.5 then you need to raise VE below 100 Hz. Don't bother looking at the trims at WOT.

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the trims are 0, they dont update.

i was able to adjust afr by lowering the ve at 1600. sweet spot was at 101, do you smooth out the slightly lower points? at 1400 and 1200?

Are you using the 3000GT EFI XML that was provided with the Chrome V2 software? Screen shot of Evoscan logging your car?

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Originally Posted by Jimvr4

Are you using the 3000GT EFI XML that was provided with the Chrome V2 software? Screen shot of Evoscan logging your car?

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Yes i am, i can get a ss later. everything else is logging, 2 byte load and airflow...the request values are correct...

How long have you let it idle, or drove below 30% throttle?

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Originally Posted by CoopKill

How long have you let it idle, or drove below 30% throttle?

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In an attempt to let it start trimming, I let it idle for about an hour. I moved it around the parking lot maybe 3 times in that hour, definetly under 50% throttle. Afterwards I took a 35 mile cruise in 5th @ about 2-2.5k rpms aswell.

I am going to go in on the wiring with my multimeter this weekend. Theres gotta be something up. Also going to format a miniSD and try to log from the tactrix directly. Hope for some results.


Correct me if I am wrong tho, but if I want to make some 1/4 mile passes, I only really need to tune for WOT? since open loop the trims wouldnt be used anyway. Getting the trims logging and set correctly is just going to improve gas mileage and drivability? Car drives great in closed loop at the moment, no knock up to 14psi (havent has the urge to go further yet lol), feels and sounds amazing...

I wanna add, the more I am driving it slowly, and letting it just idle, the better the gas mileage I am getting. First tank yielded about 120 miles, running rich. 2nd tank is about 150. now third im at 150 miles and still a 1/4 left. maybe its just since im staying out of high boost tho

Yes, It runs in closed loop at idle and cruising at vacuum. When you go into boost it goes into open loop pretty quickly. Good fuel economy depends on keeping out of boost.

If you want to make some 1/4 mile passes just make sure you tune well for WOT.