WB 02 doesn't follow commanded AFR

[LS1_Dragster]

My AFR reading from my wideband O2 is always a little richer than the commanded AFR even though the STFT's are adding and subtracting fuel. The computer thinks it's hitting the 14.68 mark by using the STFT (pulls up to 2% fuel) but the actual AFR is more like ~14.2.

How to get them to match up closer? Do I change the B4105 O2 switch points to lower numbers then 450? It seems that I need to start lowering the numbers so the computer will switch at a leaner point. Am I on the right path or is there a better way?

Lee

[odd boy]

what ecu is this?

[WeathermanShawn]

Lee:

Are you running SD Closed-Loop?

Also, is your wideband on a serial connection or analog. 95% of the time this usually comes down to a wideband issue. Stoich is 'always' stoich..so your narrowbands will switch properly if new and uncontaminated. There is also usually a setting in your wideband software for different fuels/AFR's etc. Double-check that.

You can lower the O2 mv's, but that really should not be the issue.

Give us more info..:)

[mr.prick]

I've found that after filtering the WBO2 Lambda values can be used on the O2 switch point table
to get actual AFR, EQ, Lambda closer to commanded in CL.

This may not be the right way to do it but it's the only way I've been able to get actual EQ right in CL.
OL MAF & VE tuning is done for me and LTFTs are pretty much 0%

Injector timing may also be another way to do this. :nixweiss:

[LS1_Dragster]

The computer is the 0411 with custom OS and the LC1 serial wideband in semi-closed loop speed density. This is in my 71 firebird with a L29 454. I also have the same problem with my 97 Yukon with a 0411 computer and LC1.

[tor1965]

Hi
I know this isn’t off any help, but I am in the same situation. My lc1 show about 14,2 when the engine runs closed loop. This is no matter what the fuel trim is. I was so frustrated that I bought a new lc1. This new one shows exactly the same as the old.
After that I have changed from the ls1 to a brand new ls3 that I run on the f body pcm.
I bought a new 411 pcm and new narrowband sensors, still the same readings. I wonder if my problem can be a clogged cat, or that my wideband are mounted a bit to close to the cat. The only thing that is left now is the wiring harness fuel system and the exhaust. I also hooked up an exhaust 4 gas analyzer that confirmed the 14.7 afr when the wideband was showing 0.4richer. I am using a serial connection from the lc1 to the v2.

[WeathermanShawn]

I think the location of the wideband sensor is often overlooked. The location of these sensors should be pre-cat (per Innovate Manual..Tm). Perhaps at WOT it may not be as critical, but cruise and Idle also seems off if you go post-cat.

Lee, that may not be your issue. I would be curious to see a log with Lamba or EQ vs STFT's. If the location of the narrowbands and wideband are nearly identical, then both better read the same at stoich...

[LS1_Dragster]

I have shorty headers and the O2's are right at the ball and both O2's are exact distance. Both O2's are just minutes old so they're fresh and should be accurate.

It appears that it might be the LC1, I put on the one off the dragster and the same thing so all 3 LC1's report richer. So do I assume the LC1 is correct? Or should I even care?

Lee

[Chevy366]

When you free air calibrate the LC-1 what does it read ? 20.8, 20.7 ?
Have you checked to make sure the LC-1 is set correctly in the LogWorks software and what firmware version are you using ? Try flashing back to V1.0 instead of v1.10 if that is what you have .

[LS1_Dragster]

When you free air calibrate the LC-1 what does it read ? 20.8, 20.7 ?
Have you checked to make sure the LC-1 is set correctly in the LogWorks software and what firmware version are you using ? Try flashing back to V1.0 instead of v1.10 if that is what you have .

Seems like it was just 20% but I will check it again. I will also check the version.....