School me on O2 switchpoints

[maudyZ28]

exactly what it should do.

Be very careful to disable all fuel trimming when tuning with the WB. The auto VE tutorials tell you what you need to dissable and what is providing your fueling.

I run a 99 camaro , I assume you run a 98 camaro or TA ?

[ddnspider]

exactly what it should do.

Be very careful to disable all fuel trimming when tuning with the WB. The auto VE tutorials tell you what you need to dissable and what is providing your fueling.

I run a 99 camaro , I assume you run a 98 camaro or TA ?

Per the AutoVE and AutoMAF tutorials I disabled all LTFT's and STFT's when using the wideband so they do not mess with my VE or MAF values. Then I turned them back on to go in closed loop. Technically, they SHOULD be zero if my VE and MAF changes were close, and per my log they're pretty close other than idle and WOT. Did I miss something?

I have a 10 Second 1998 TA M6 thats turbocharged and fully built. Been on a few magazine covers. I had someone tune that a long time ago. I've been wanting to get into tuning so found a good deal on a 1998 Z28 A4 that was basically stock, which I thought would be a better starting point to learning than the TA thats heavily modded lol. However, after looking at the tune in the TA I'm tempted to completely redo it, but its tough to tune a boosted 98 properly cause of the PCM limitations.

[maudyZ28]

Everything you have done is totally correct.

As we discussed, idle will be off due to slow switching. So if you are happy the WB says it is the correct AFR then you can tweak the NB switch points to get a better CL AFR. If the +5% LTFT makes a noticeable difference.

The second +ve trims at WOT are due to the fact that the PCM will add fuel trims from general CL driving to any fueling added at WOT to be safe. However the PCM will NEVER pull out fuel, so if you have -ve fuel trims then the PCM will only run at WOT direct from the MAF or VE table only. If your trims are about zero, then just add to your VE and MAF by say 0.5% (but not in WOT/PE areas) so the CL trims go negative and thus never add fuel to the WOT region where you have WB tuned

10s TA sounds awesome dude. Hoping to break 11s with my head/cam camaro. I dont know the specifics of the 98 PCM as I was lucky with a 99 and have upgraded to COS3 so can run a 3 bar map sensor and boost VE table if I wanted.....you thought about re-pinning a 99 PCM ?

[ddnspider]

Everything you have done is totally correct.

As we discussed, idle will be off due to slow switching. So if you are happy the WB says it is the correct AFR then you can tweak the NB switch points to get a better CL AFR. If the +5% LTFT makes a noticeable difference.

The second +ve trims at WOT are due to the fact that the PCM will add fuel trims from general CL driving to any fueling added at WOT to be safe. However the PCM will NEVER pull out fuel, so if you have -ve fuel trims then the PCM will only run at WOT direct from the MAF or VE table only. If your trims are about zero, then just add to your VE and MAF by say 0.5% (but not in WOT/PE areas) so the CL trims go negative and thus never add fuel to the WOT region where you have WB tuned

10s TA sounds awesome dude. Hoping to break 11s with my head/cam camaro. I dont know the specifics of the 98 PCM as I was lucky with a 99 and have upgraded to COS3 so can run a 3 bar map sensor and boost VE table if I wanted.....you thought about re-pinning a 99 PCM ?

Thanks Maudy, Good luck with 11's on your camaro. I am sure you'll get there. I have thought about repinning to a 99PCM. The car has been "finished" for over years so I guess the thought of repinning the PCM and starting from scratch on the tune is a bit daunting to me. It would be nice to have it tuned properly as I can tell from its current tune that the PE and IFR tables were raped lol.

[ferocity02]

I have a question on switchpoints. It is generally agreed to change the switchpoints to 450mV across the board. Is this from the fact that 450mV is halfway between 0 and 900mv?

What if the sensors never get up to 900mV when switching? Mine rarely get past 800mV. They are Delphi units with about 10k miles on them.

Perhaps the switchpoints should be tailored to the sensors rather than fixed at 450mv?

On a sidenote, is there a "best" O2 sensor out there? I am not opposed to changing mine if they should indeed be more active than they are.

[ddnspider]

I have a question on switchpoints. It is generally agreed to change the switchpoints to 450mV across the board. Is this from the fact that 450mV is halfway between 0 and 900mv?

What if the sensors never get up to 900mV when switching? Mine rarely get past 800mV. They are Delphi units with about 10k miles on them.

Perhaps the switchpoints should be tailored to the sensors rather than fixed at 450mv?

On a sidenote, is there a "best" O2 sensor out there? I am not opposed to changing mine if they should indeed be more active than they are.

Thats where I was originally coming from. Assuming your OLFA is close to what you want, then you should be able to log and see what your average switchpoint is based on the groupings and then set the tune for that. I know my O2's are lazy at idle due to the long tubes so I have my 2 lowest groups set below 450mV.

[ferocity02]

Thats where I was originally coming from. Assuming your OLFA is close to what you want, then you should be able to log and see what your average switchpoint is based on the groupings and then set the tune for that. I know my O2's are lazy at idle due to the long tubes so I have my 2 lowest groups set below 450mV.

For fun I set all of my switchpoints to 370 mV and there was no appreciable difference in AFR, it was still around 14.4 while cruising. But the average NBO2 voltage went down from like 460mV to 395mV. Not sure what to learn from this.

[voda1]

For fun I set all of my switchpoints to 370 mV and there was no appreciable difference in AFR, it was still around 14.4 while cruising. But the average NBO2 voltage went down from like 460mV to 395mV. Not sure what to learn from this.

Were the O2's cycling any faster?

[joecar]

Post log files of each (460mV, 395mV).

[ferocity02]

0049 is with 450mV switchpoints, 0051 is with 370mV switchpoints.