My commanded AFR is changing rich on me!

[eficalibrator]

If running with CLMAF, what happens at WOT... does the PCM still use the MAF or does it revert to VE...?

If you have it set to only use filtered MAF (max rpm to disable dynair set below idle), then it should never look at VE. Period. Going WOT would simply remove the ECU's ability to perform measurements and corrections to AFR, while still applying any positive LTFT's that may have been learned earlier.

[joecar]

Ok, so it still honors the threshold RPM (B0120) for airmass... thanks Greg...

[Chris81]

I'm going to bring this thread back up..

I'm going to do some more logging tonight to see if I can figure anything out.. but I did find this thread: http://forum.efilive.com/showthread.php?t=3840 that sounds alot like what is going on with my car. Anyone have any thoughts on this?

Thanks, Chris

[Chris81]

Has no one else had this problem?

I still need to log a little more, I had a couple of computer problems.. but its always the same thing.. commanded AFR will just drop from what i've adjusted in B3618 down to commanding 11.77.

Surely there has to be someone that has had to deal with this problem before.. I've been through every parameter I can think of numerous times and I can't find a table or multiplier or anything that would even remotely cause the Commanded AFR to change. Hopefully i'm just missing something..

Does anyone have thoughts on the post I made above with the link?

Would changing to a custom OS possibly fix this? (I had planned to go to COS5 soon for my nitrous setup)

[WeathermanShawn]

What type of tune are your running?

Did you verify if B0701 is set to 'Disable'?

If running off MAF if you're Commanded AFR does not match actual then you are overestimating CYLAIR. If running off SD, you are running off DYNCLYAIR.

Short of some programming bug, or if your method of tuning is giving you inaccurate data, it appears your DYNCLYAIR is being overestimated. Perhaps COTP, wideband error, or bad log data.

Post up a log and a tune.

[Chris81]

I still have B0701 enabled since the cats are still on.. it was turned off for AutoVE though, I wondered about that in the beginning but was told: "When cat overtemp protection kicks in, the logged commanded AFR does not include the fuel component from COTP."

I'm running a MAF tune and used AutoVE with a wideband for the VE tuning as well as the MAF table. My Commanded and Actual AFR's are usually very close, even when the commanded AFR drops to 11.77, my actual follows it down like it should. I just don't want it to! LOL

I have included my current tun. file and a log from the track in post #8 on the 1st page.

[WeathermanShawn]

I recall a somewhat similar problem once. Seems like it had to do with my Pid selection for commanded AFR and my units.

Somewhere in my scan I did not have the units reading the same parameter. I did a complete reload of the tuning and scan software. Re-validated pids etc.

Seems like it is a conversion problem. I can not find anywhere in your tune where 11.7 AFR is commanded. You could try disabling COTP and see what happens.

[Chris81]

O.K., now I understand what your saying.

I recall a somewhat similar problem once. Seems like it had to do with my Pid selection for commanded AFR and my units. Somewhere in my scan I did not have the units reading the same parameter. I.E. AFR vs EQ.

I think a complete reload of the tuning and scan software. Re-validated pids etc.

Seems like it is a conversion problem. I can not find anywhere in your tune where 11.7 AFR is commanded. You could try disabling COTP and see what happens.

Need Joecar or expert to jump in.

..WeathermanShawn..

I have wondered about my units being off in the scan tool (something like that has happened to me as well, but mine was a scaling issue), but I figured that if that would have happened that my commanded AFR being logged and what my actual AFR is wouldn't jive.. for example my actual would be correct but my commanded would be off since all the scan tool is doing is "scanning" and not able to change things up. does that make sense? LOL

I will for sure do some more logging tonight with COTP off as well.

[WeathermanShawn]

Chris, your log is the first one I have ever seen where you have +Ltrims between shifts. Maybe you just shift better than me. Every log I have at WOT I enter at negative trims, and between shifts stay at 0.0 Ltrims.

Yours go positive. Really your entire Ltrims never go negative. Are you carrying +LTrims into WOT? Now why that would change your commanded AFR is beyond me. Just wondering what is happening to those +Ltrims? The software says 0.0, but when you shift they are right back there.

Is it possible your +LTrims are getting added to your commanded AFR? That percentage of Ltrims would make your AFR at ~11.7.

[Chris81]

My trims are goofy because I need to dial it in some more, I changed a couple of things and haven't adjusted for them yet, as well as the Vararam CAI I have always seems to sway trims more so than F-body stuff.. usually my avg. LTFT's are +2 so.. they were going positive between shifts because its trying to command 14.68 for that time in between. When it starts to command 11.77 all the trims are zero.