upper vs lower o2 sensors vs tuning
03-24-2011, 11:16 AM
#1
upper vs lower o2 sensors (over correction!)
The situation...
A/F will generally be spot on during warmup and initial driving. Corrections are +/- 5% and make sense -- e.g. bank one goes a little lean then the ECU instantly adds 5% to bring it back and vise versa.
Once the car is warmed up and I'm just light cruising, maintaining speed ect, everything is fine for maybe 30 sec then all the sudden the A/F on both banks will begin slowly dropping... hovering between 12.5 and 14.0. At the same time, the ECU is ADDING FUEL, sometimes up to 10-15% on both banks.
As soon as I get on it a bit the A/F jumps back to the target A/F.
Things I've done since this started happening -
1. Installed non-foulers (2" length approx.) as I was getting codes due to my HFC's
2. Upgraded from 440-600CC
3. Retuned to the 600CC's (but this happened both before and after retune)
And yes, I do have the correct dead time and latency dialed. I even tried making it excessively low and it made no difference at all in my problem other than expected, e.g. decel became too lean.
It just makes NO sense that the A/F target is 14.7, the upper sensors read 12.5-14.0, and the ECU keeps _adding_ more and more fuel!!
So... does the ECU sometimes switches to the lower o2 sensors for corrections at which time my non foulers are f'ing everything up??
Any clue?
A/F will generally be spot on during warmup and initial driving. Corrections are +/- 5% and make sense -- e.g. bank one goes a little lean then the ECU instantly adds 5% to bring it back and vise versa.
Once the car is warmed up and I'm just light cruising, maintaining speed ect, everything is fine for maybe 30 sec then all the sudden the A/F on both banks will begin slowly dropping... hovering between 12.5 and 14.0. At the same time, the ECU is ADDING FUEL, sometimes up to 10-15% on both banks.
As soon as I get on it a bit the A/F jumps back to the target A/F.
Things I've done since this started happening -
1. Installed non-foulers (2" length approx.) as I was getting codes due to my HFC's
2. Upgraded from 440-600CC
3. Retuned to the 600CC's (but this happened both before and after retune)
And yes, I do have the correct dead time and latency dialed. I even tried making it excessively low and it made no difference at all in my problem other than expected, e.g. decel became too lean.
It just makes NO sense that the A/F target is 14.7, the upper sensors read 12.5-14.0, and the ECU keeps _adding_ more and more fuel!!
So... does the ECU sometimes switches to the lower o2 sensors for corrections at which time my non foulers are f'ing everything up??
Any clue?
Last edited by djamps; 03-24-2011 at 11:24 AM.
03-24-2011, 12:10 PM
#3
^^ LOL thanks
I guess the best thing to do is remove the non foulers and see what happens...I can live with codes if it means my low load A/F will stabilize...but I was just hoping someone knew how the ECU worked. It's pretty crazy how limited the knowledge is about our ECU's compared to other platforms.
I guess the best thing to do is remove the non foulers and see what happens...I can live with codes if it means my low load A/F will stabilize...but I was just hoping someone knew how the ECU worked. It's pretty crazy how limited the knowledge is about our ECU's compared to other platforms.
03-24-2011, 01:21 PM
#4
^^^ Why do you have antifoulers in for your downstream sensors. You can just disable the codes as well. Also to answer your question in the other thread. I beleive Minimum effective Injector pulsewidth is the lowest value the ECU wants to see your injectors at so with 600cc injectors ur prob right around 2.0ms at idle so if you have left that value at stock(2.4ms) then try lowing that value. I always set that value for the 600cc cars i do to 1.5ms
03-24-2011, 01:26 PM
#5
^^^ Why do you have antifoulers in for your downstream sensors. You can just disable the codes as well. Also to answer your question in the other thread. I beleive Minimum effective Injector pulsewidth is the lowest value the ECU wants to see your injectors at so with 600cc injectors ur prob right around 2.0ms at idle so if you have left that value at stock(2.4ms) then try lowing that value. I always set that value for the 600cc cars i do to 1.5ms
I tried everything with the injector latencies (starting with the actual values from DW) both dead time and 12-14v values everything from 1.0 to 2.0 msec and it did nothing to stop the low load fluctuation, all it really did is cause excessively lean or rich decel.
i really hope its the antifoulers as I never ever had this issue before and i'm sure my gas mileage is taking a huge hit (probably the cats too).
Last edited by djamps; 03-24-2011 at 01:29 PM.
03-24-2011, 01:37 PM
#7
^ I'm running 1.5ms dead time already, I think I went as low as 1.2 or so but no diff in low load stability (other than lean as heck decel).
I'll note that this also happens sometimes under moderate load where the injector time is well over 2ms..it's not LIMITED to low load but is more typical there.
Either way, I'll pull off the nonfoulers and we shall see if anything changes.
I'll note that this also happens sometimes under moderate load where the injector time is well over 2ms..it's not LIMITED to low load but is more typical there.
Either way, I'll pull off the nonfoulers and we shall see if anything changes.
Last edited by djamps; 03-24-2011 at 01:38 PM.
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03-24-2011, 01:48 PM
#8
^ I'm running 1.5ms dead time already, I think I went as low as 1.2 or so but no diff in low load stability (other than lean as heck decel).
I'll note that this also happens sometimes under moderate load where the injector time is well over 2ms..it's not LIMITED to low load but is more typical there.
Either way, I'll pull off the nonfoulers and we shall see if anything changes.
I'll note that this also happens sometimes under moderate load where the injector time is well over 2ms..it's not LIMITED to low load but is more typical there.
Either way, I'll pull off the nonfoulers and we shall see if anything changes.
03-25-2011, 12:58 PM
#12
Well I pulled the non foulers today and went for a quick drive... I didn't see any more A/F 'float' and the car actually feels a little more peppy down low...it was only a 10 minute drive so I don't know for certain if it's 100% fixed but it's definitely better...
03-26-2011, 04:02 AM
#15
Yea I can't believe it.... those lower o2's do alot more than everyone led me to believe over the years. The antifoulers really turned my idle and cruising tune to ****. Without them the A/F is now dead on 14.7 with almost no variance in idle and cruise now. Even the occasional overshoot when going on/off throttle are corrected within a second or two instead of hovering around aimlessly rich until I either get on it or let off.
Summary: if you've got antifoulers on your lower o2, take that **** off.. They mess your tune up in ways that cannot be tuned out. Not just lower MPG's but possible HFC damage as well based on what I saw my A/F doing.
Summary: if you've got antifoulers on your lower o2, take that **** off.. They mess your tune up in ways that cannot be tuned out. Not just lower MPG's but possible HFC damage as well based on what I saw my A/F doing.
Last edited by djamps; 03-26-2011 at 04:25 AM.
03-27-2011, 03:26 PM
#19
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Disabling codes
I'm also a 2004.5 with wideband, so this thread was perfect timing for me too.
Thanks!
03-27-2011, 03:37 PM
#20
How do I go about disabling the codes? Is this something that would be possible with UpRev Tuner? I have test pipes and was about to install non-foulers and purchase Osiris Tuner until I read this thread.
I'm also a 2004.5 with wideband, so this thread was perfect timing for me too.
Thanks!
I'm also a 2004.5 with wideband, so this thread was perfect timing for me too.
Thanks!
Last edited by cdoxp800; 03-27-2011 at 03:39 PM.