How to verify your wide band is correct?

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12-10-2019
shinyrust

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How to verify your wide band is correct?

I am having trouble with my fuel trims. I posted the tune but I just made adjustments to the pulse width (a recommendation from a fellow tuner on FB) to match the TBSS factory injectors. What I notice is that I can tune to the wide band to within 1% on MAF or VE and then when I enable LTFT and DFCO and everything else that was turned off, the LTFT max out at 25 and then STFT will be somewhere around -10 to -8.

The log file is from yesterday. It shows the craziness of this tune I royally screwed up.

I am about to redo the MAF calibration since I changed the pulse width. If anyone has any suggestions I am all ears.

Thank you all

Side note:

AEM wide band 30-4110
TSP stage 3 Low Lift truck cam
TBSS intake with factory injectors, corvette filter, 90mm TB
Pacesetter long tubes into gibson sport truck exhaust.
12-10-2019
Lakegoat

I'm looking at your short term fuel trims and there is nothing wrong there. I see one cell that has an 8 in it and that is very low rpm so it's where you let off the gas. Any sharp pedal changes will get you some goofy numbers. I couldn't see the LFTF's since I don't have mine on at all. Leave yours off for a while and just look at STFT's and your wideband. Your Eq ratio looks crazy, but there again, everytime you get on the gas and off the gas, the numbers are going to look bad. Drag your cursor across the bottom where you are going a steady speed and look at the eq numbers. Then do the same when you are wot--only when you have the pedal planted. That will give you a better idea of what is going on. You can block out a lot of the trash.
Drive with STFT's only in steady state driving. Then turn off STFT's and use only your wideband in open loop, same steady state driving.. Compare the two. They should be close.
If you changed the pulse width--yeah, you need to do some retune.
12-10-2019
shinyrust

4 Attachment(s)

Quote:

Originally Posted by Lakegoat

I'm looking at your short term fuel trims and there is nothing wrong there. I see one cell that has an 8 in it and that is very low rpm so it's where you let off the gas. Any sharp pedal changes will get you some goofy numbers. I couldn't see the LFTF's since I don't have mine on at all. Leave yours off for a while and just look at STFT's and your wideband. Your Eq ratio looks crazy, but there again, everytime you get on the gas and off the gas, the numbers are going to look bad. Drag your cursor across the bottom where you are going a steady speed and look at the eq numbers. Then do the same when you are wot--only when you have the pedal planted. That will give you a better idea of what is going on. You can block out a lot of the trash.
Drive with STFT's only in steady state driving. Then turn off STFT's and use only your wideband in open loop, same steady state driving.. Compare the two. They should be close.
If you changed the pulse width--yeah, you need to do some retune.

I just got back from doing some MAF tuning.

#1 Do you tune the MAF around idle areas?

#2 I noticed in some cells that the STFT was adding 50% or removing 13.x% all the while the wide band is saying 0.92 to 1.06.

#3 When I set up the histogram for the MAF it is based on the EQ. So if the computer is adjusting the fuel am I getting an accurate measurement or am I simply adjusting an already corrected value made by STFT?

Attached are the logs I used for the adjustments made to the MAF starting at 20-03 and ending 20-40.

Thank you
12-10-2019
kingtal0n

some ways to tell
1. experience, after 20 years of looking at the wideband I can just tell if its working or not. behavior is very consistent throughout the years, many cars, use AEM wideband (affordable).

2. scanner, If you have any doubt you can use the scanner to mess with a/f ratio and if configured properly, OEM ecu (hptuners) is pretty much dead-on accurate adjustments will tell if wideband is working or not. i.e. 15:1 to 14:1 will yield a sloping a/f behavior at the wideband similar to what you would expect.

3. narrowband, Finally if you have closed loop narrowband you can activate that and ensure the wideband zips to 14.7ish.
12-11-2019
Lakegoat

If you have stft's active when you are watching the wideband, the stft's--O2 sensors--are trying to get the tune back to stoich. That's why Lambda doesn't fluctuate as much as the stft's. Turn off stft's and tune with your wideband in open loop. Get that correct and yoyr stft's should be back in line.
Be sure and clear fuel trims with thescanner after each tune change. Then drive for a couple of minutes before you start scanning again.
12-11-2019
shinyrust

Quote:

Originally Posted by Lakegoat

If you have stft's active when you are watching the wideband, the stft's--O2 sensors--are trying to get the tune back to stoich. That's why Lambda doesn't fluctuate as much as the stft's. Turn off stft's and tune with your wideband in open loop. Get that correct and yoyr stft's should be back in line.
Be sure and clear fuel trims with thescanner after each tune change. Then drive for a couple of minutes before you start scanning again.

That's what I thought. I was pulling my hair out. Then I noticed the STFT adjusting. Thought to myself that if they are trying to fix the tune while I'm trying to fix the tune....

Thank you and everyone else for your help!