is it really just lag though, or does the lower temperature reduce the max voltage? (i've definitely recorded that it does)
obviously that has to mess with the median value it uses for AFR.. im just not sure how much
i wouldn't really care much if my o2s were equal temperature.. being 1% off in total is no big thing, but being off 1% on only one bank bugs me
Just asking questions... Have you recorded temp as well as voltage? Does the sensor tend to spend more time below .45 as well as show lower peak which would indicate a lower median is needed?
I don't know how the algo calculates lag. Time to attain switching voltage after rich/lean limit is reached must be a part of it. If either limit isn't attained, well, how does the algo deal with that?
Sometimes when the sensor is moved it actually reads a different O2 content. The combustion reaction is still taking place as exhaust exits the engine so the free O2 content farther down the pipe can be different than near the ports. Cold pipes and lower peak suggest reaction is stopping or slowing in your case but that's not always a given. Retard timing a few degrees and see if it changes.
Adam might be able to look at it and tell. May also be similar to $0D as I have noticed many things that overlap into the 98 style Blackbox.Originally Posted by EagleMark
lower temps should reduce the severity of both directions that the O2 will swing in.
1995 Chevrolet Monte Carlo LS 3100 + 4T60E
it's always felt like i have a lean bank too, you know that feeling of a twin cylinder bike when one cylinder is weaker, and you can feel one fighting to keep the other running? i did plug chop the plugs that are easy to get at, and confirmed the bank that was blm split 8-10 lower than the other was running lean.
the entire thing that started this was when i was evaluating my blm splits (of which there were multiple causes), you could see clear as day in the datalogs that one o2 voltage was always peaking a little bit lower. i changed them, thinking one was on its way out, and brand new o2s in a different brand did the same thing
so i scoped both o2s while running hot open loop at 2k (unloaded, though), of course in open loop they hung rich, but it matched what my datalogs showed, the further o2 definitely read lower peak voltage. then i scoped them in closed loop to get them switching. it was hard to read true median voltage (this is a tube scope we're talking here), but the peak of the colder o2 was definitely lower when switching too. i checked temperature on both heads in a few spots, the entire bank that was reading lower peak voltage was definitely leaner (i forget the temperature difference now..)
i did a temperature check after adding 50mv to the median value of the colder o2, and it was almost bang on.
i have yet to do low rpm individual cylinder balancing due to lazyness, so i did all my checks at around 18% tps, which is past the range where those trims are active in my tune
it's possible something else is going on and i'm chasing a ghost, but so far every test i've done hasn't turned up anything. kind of a fun problem to work on.
cool, i'll get $0D and see what's in there.
now that's one thing i didnt notice...... hmm
but maybe the accuracy of readings down around the range of 'almost nothing' is a bit lower on my crappy old tube 'scope.
I've used some digital scopes that are just plain wrong for automotive use yet they're marketed that way. Tube scopes can have their place. You wouldn't believe the reactions when I drag out my 1968 Heathkit for a DIS issue.
So the long bank O2 reads lower in OL.i did a temperature check after adding 50mv to the median value of the colder o2, and it was almost bang on.
BLM shows additional fuel to compensate.
You've increased the long bank target switching (median) voltage to nearly .5 volts.
BLM now shows nearly correct.
Is that correct? Because it's very interesting.
Increasing the switching voltage generally moves BLM in the same direction. Adjusting median voltage richer tends to move the BLM richer as the pcm is forced to add fuel to maintain the higher average voltage. But in your case the result is opposite. This is why I love tuning. :)
I'll propose a counter theory. Temps are lower, of course, but that's not directly causing the O2 readings to be lower. Instead, I'll bet the end of the combustion reaction is slowing in the pipe so more free O2 is passing the sensor. By increasing the target voltage you add just enough fuel and heat for the reaction to continue and once it does, and the pipe's warm, O2 content at the sensor is closer to what's expected. Other ways to test would be four gas analyzer (expensive), heating exhaust with outside heat source, retarding timing slightly.
Just thought of something. Isn't there a per cylinder timing adjustment for injection? Was that done to account for timing chain wear? If so can you slightly delay the start of injection for that bank and see if the stock median works?
i'll buy your counter-theory. i don't know for sure that it's temperature related, and have no evidence to suggest otherwise.
i thought it was the other way around. lets say 450mv is optimal (actually 425 in the stock EE bin, probably for economy reasons), you drop it to 425. now 425 is the ideal thing to try to land on, and it trims until it gets there.
wouldn't increasing switching voltages make it try to land on a slightly richer mixture, which requires LESS fuel?
or trying to average 425mv would require less fuel (slightly leaner)
several tune-by-mail tunes i jacked that were intended for 'economy' set the o2 swing threshold slightly lower
of course these are narrowband o2s, if you're off by more than 50mv, you can't trust anything, right?
i want to do more tests. maybe it was just a fluke and my blms just seemed more even. i'm pretty damn sure my remaining blm splits are from o2 sensor distance. i can't find any other thing that might cause them
is there a per cylinder adjustment? yes. is it done to account for timing chain wear? no. it's done because the LT1 plenum feeds the cylinders unevenly at lower rpms due to some weird runner configuration. in EE it's a pulse width multiplier, not a timing adjustment. all injector timing is global.
new version out. starting to document everything in the descriptions. added that elusive CCP fuel compensation setting. seperated corvette specific stuff into different categories
http://resfilter.net/files/carstuff/EEX/EEX_1c.zip
next big update.. way different than the old one
now it's a totally unique definition that's a lot easier to read and work with, especially for a new tuner. almost everything has a description now
can add this to the EE thread if you want to
http://resfilter.net/files/carstuff/EEX/EEX_2.0.zip
i'm a new tuner willing to experiment...... but I think your link is broken.
Yeah all the links are broke! He was doing some great work on the $EE mask as well. I had a link in the $EE info thread but took it down as they are dead.
We really need to store and host shared work here where it's safe and available.
I did find the latest one I had before the links crashed?
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
Thank you,
just to confirm (I think I read somewhere) that EE code is for the 1994 Lt1?
16188051
NOTE: Requires 3rd party software to upload tune
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