BS3 lost correction and AFR stuck on 14.38

[pcn]

While testing this weekend I noticed a couple of what I thought were hiccups during a couple runs. The AFR would jump to 14.38 or so and then back close to target. I also noticed that near those times the RO2_Corr value went to zero. For fun, I loaded swapped in the first tune of the night to see if any of my changes were the cause. On that run the car ran the same time as at the beginning of the night, but the AFR was a constant 14.38 and I now have no fuel correction. My guess is the AFR issue is a bad O2 sensor, but would that also affect the correction reading? I've read about verifying a "R_RiOhms" value but I cant find it. Is that because I have the base system? If not, where do I find it? Can I test the sensor without the car running, since I'm concerned about the 14.38 AFR? Finally, if it's bad, what sensor do I need? Thanks for any and all direction!

 

[HighPSI]

When the wbo2 values go out of range, the bs3 will quit using it for correction. It uses the inexpensive Bosch WBO2 that most gauges use. It can be bought at your local parts store for around $60. Should be able to do a search and get the part number

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[pcn]

Thanks very much! and that does make sense based on what I saw because the car ran the same ET and mph while "logging" the 14.38 AFR.

 

[Rafs-T-Type]

Mine started doing the same thing on my scanmaster after winter storage. I just drove the car a little hot a couple times and it came back to life.

 

[norbs]

Read how to test the o2 sensor.......

http://www.turbobuick.com/forums/threads/o2-sensor.398937/#post-3249372

 

[pcn]

Update, it's a Bosch 17205 Oxygen Sensor, best price online is Autoplicity @ $68. local parts stores wanted $100+ for it. Thanks for the replies!

 

[norbs]

Not a bad price to keep a spare one on hand. The bosch sensor is really a fast response sensor, but the trade off is sensor life since it has a smaller area inside to clog up than the NTK.

 

[pcn]

I may have run into the sensor life issue, as I think mine died while I was trying to adjust A/F while on the 2-step and right after the 2-step. I cant find anything that ties the 2-step (external Digital 7) to the tune, so I'm not sure what to do around the 2-step RPM. When it's on the 2-step it would seem that there would be excess fuel and fouling the plugs, but in my logs it stays lean for at least .5 seconds after I'm off the 2 step.

 

[norbs]

Turn down your O2 correction limits near the 2 step rpm this will prevent big swings in af ratio due to o2 correction, you probably wont need to rely on o2 correction if your tune is close.

 

[pcn]

Thanks, I will check those and see where they are set

 

[pcn]

Well, maybe this is a Fast only option? On my BS3 I have Positive and Negative Fuel Correction tables, but they are boost dependent, not RPM. I havent found anywhere to modify correction by RPM. In the cells near the 2 step RPM, my original tune seems to have low vaues relative to the other cells. Maybe the tuner was compensating by leaning it out in the fuel table? I loaded a copy of the correction table and replay, if it might help.

 

[turbodaniel]

Well, maybe this is a Fast only option? On my BS3 I have Positive and Negative Fuel Correction tables, but they are boost dependent, not RPM. I havent found anywhere to modify correction by RPM. In the cells near the 2 step RPM, my original tune seems to have low vaues relative to the other cells. Maybe the tuner was compensating by leaning it out in the fuel table? I loaded a copy of the correction table and replay, if it might help.

On my positive and negative 02 correction the map/kpa corresponds with rpm,there is no /psi... whatever your 2 step is set at, set your o2 correction to 0. Im no expert but thats what Cal Hartline did on my BS3

 

[pcn]

Can you post a acreen shot of that please? Now I do have my minimum rpm for O2 Correction to turn on set above the two step. Its under Parameters if I remember right.

 

[turbodaniel]

Can you post a acreen shot of that please? Now I do have my minimum rpm for O2 Correction to turn on set above the two step. Its under Parameters if I remember right.

This is my old setting, Cal adjusted it to 0 at 129

 

[pcn]

OK, that's where I thought you were talking out. Yours is just in KPa rather than psi. that looks like anoher way to turn it off, compared to in the AFR parameters window were I've got mine to come on after 4200, the 2-step is set to 3500. Since I dont drive on the street he didnt worry about correcting below the 2-step rpm. I can see if one wanted correction below and above a certain rpm that would be a way to block out correcting at a specific rpm. Since mine doesnt correct until 700 above the 2-step I dont see any correction while it's on either.

In my question above I was trying to ask how do you know what to put in the fuel map at the point it's on the 2-step. You cant use the AFR reading to tune on the 2-step, so do you tune it at that rpm without the 2-step? When you turn on the 2-step it's not firing different cylinders so arent you running rich for the time it's on the 2-step? If so, wouldnt I want to back off the fuel somehow? But if I back off the fuel, the cyclinders that ARE firing will be lean. Or does it not really matter since the 2-step should only be on for a couple seconds? Maybe I'm thinking about unfired fuel washing and damaging the cylinders. I dont think my logic is good here. My intuition tells me that I should tune it under WOT before, through, and after the 2-step rpm. Then after it comes off the 2-step it shoud be making the right AFR ratio, and it has only a brief (700 rpm) delay before the computer starts any autocorrection.