High o2 fuel trim, high fuel trims in general

[symple]

Hi, just looking for some advice on my fuel trims.

I'm running the stock 450s and stock MAS with just the lower honeycomb removed. I have a rewired walbro 190 installed and no AFPR.

FTRL = 118.7%
FTRM = 100.0%
FTRH = 105.4%

at WOT, my FTO2 is 100.0%

However, at idle and crusing speeds the FTO2 bounces from high 80%'s all the way up to 197%.

Most of the time, the high 02 trims occur at idle (between 600 and 850 RPM.)

RPM Timing FTo2(%) TPS(%)
781 10 175 10.1
750 8 199.2 10.1
2906 38 148.4 17.9
968 6 184.3 16.4


There are a TON more 10.1% throttle 7xx RPM FTO2 numbers that are high like the first two. I'm not sure why 10.1% throttle is "idle."

Any suggestions?

Thanks,
Symple

 

[WhiteTsiAwd]

Your fuel trims dont look all that bad but when your not at WOT then you O2 will bounce around all the time. Well while ur in open loop anyways. And since your a 90 O2 dont really mean a lot, and im pretty sure that you need to be looking at your O2-R....

Cody

 

[Enigma_Man]

The ECU ignores the O2 sensor at WOT, so you can too

Otherwise, I'd build an intake leak tester, and give that a whirl.

-Jesse

 

[symple]

Sometimes the o2 voltage stays really low... like .00 .03 .07 etc. at idle and at crusing speeds while not under load. It should oscillate all the time while at idle and with no load right?

Intake leak tester built... I'll see what happens with that tomorrow.
MMCD still reads 10.1 % throttle at idle...the AFC says 0% though.


Thanks for the help!

--Symple

 

[WhiteTsiAwd]

MMCD will always read something for your TPS at idle. Think of it like this, the throttle body is open at idle, obviously, so it will draw in air. Yours is open 10.1% which shows on ur logger. However i guess the AFC takes that into consideration and just makes idle 0%. So when your AFC says, lets say 20%, then its actually 30% in your case.

Thats my understanding of it, but i am probably completely off...

Cody

 

[nine5raptor]

The mmcd reports the actual voltage signal from the tps. The afc on the other hand scales it's tps values to the min/max that it sees.

 

[WhiteTsiAwd]

The mmcd reports the actual voltage signal from the tps. The afc on the other hand scales it's tps values to the min/max that it sees.

^^^My thoughts exactly.