Guys

I got my STFT's pretty much nailed to 0-2% last night, however, the car idle's around 16:1

I searched around and couldnt figure out what I needed to scale in order to fix the error between the actual wideband readings, and the AFR table within ECU Flash

It would seem it needs around an 8% correction based upon the logged AFR from the wideband, and the fact I have 14.7 input into the AFR table.

Thanks

ANdy

 

STFT should move around quite a bit. LTFT is what you can get to be relatively stable.

Verify yout LTFT lo and mid are good.

 

If you've got the latencies dialed in pretty good, the STFT should not move around that much. Everyone shoots for +/- 5% and mine logged for 10 mins do not exceed +/- 2% from 0. However, the car is too lean for idle

 

This is only at idle that i'm talking about as well, i should add...I will dial out the LTFT's with injector scaling once I am happy with the idle....

 

What is your LTFT low at? Is it maxed rich (+12.5%).

STFT is your short term fuel trim that is a rapid adjustment based on O2 feedback. If you sit there log enough, of course it will bounce around 0. The postive or negative will be pushed into the LTFT.

That is what 03white was asking you. Check your LTFTs. Your selected LTFT + STFT is your true fuel correction. You don't really need to idle or cruise any amount of time. Adding those two together will show you where your LTFTs will end up.

 

IIRC......(and ironically) LTFT was around the -8% mark...

So to fix this, I need to adjust the scaling down 8%, continue to let it idle, and both the LTFT and STFT should come around. Is that correct?

 

If your LTFT Lo was -8% and your STFT was bouncing around 0, then you need to take out 8% of fuel. That would be increasing scaling. But, depending on what your LTFT Lo and LTFT mid settles at, you may need latency adjustment, scaling adjustment, or both.

 

I was originally at -8.5% correction on the LTFT low. I bumped the scaling from 1008 to 1083 and let the car idle for 20 minutes. I am not sure why, but the LTFT did not budge from -8.5%

Consequently, the STFT was sitting around 16-18%+ the whole time.

 

Something is up. I had a 20+Min drive into work today so I logged the whole time. My LTFT Low did not move from -8.5276. (this is after moving scaling from 1008 to 1083) Another thing thats funky is my STFT Mid-s arent even populating. They show the default value of 0.1008

My log is here if anyone is interested in looking at it..

http://www.booztd3.com/Pictures/Tech...0_14.33.52.csv

 

make sure your rear O2 is not disabled, as that can make your fuel trims not read.

 

You don't rescale the AFR map value to get it to match up better with the wideband. You need correct injector scaling and latencies, and correct MAF scaling.

Plus, when you're talking about closed-loop mode, the AFR map is ignored and 14.7:1 is assumed.

 

Where is the wideband o2 sensor in the exhaust stream?

 

Downpipe, before the hi-flo cat

 

The AFR table in ECUflash is just a number. It's highly, highly unlikely that the AFR value in that table will match the wideband.

 

Yep, since I originally posted this, I have picked up a significant amount of knowlege about how all this works.

I created an excel spreadsheet that has a handy calculator in it for figuring out what you need to modify your AFR table to, based on logged AFR's.