Wot runs get progressively richer
the sensor sees something it "thinks" correlates to stoich
incoming AFR. Though actually any thinking happens
downstream. This falls apart with any excess exhaust
oxygen, or a cold sensor whose switching becomes
asymmetric (faster L-H than H-L response time) when
cold, etc.
You can see oscillation with a wide range of duty cycles
and averaged voltages, across a fairly wide range (like
13:1 - 16:1). Not sure where switching totally snuffs out
and sticks to one end or the other, but I've played with
pulling / pushing closed loop AFR by NBO2 pivot voltage
and watched the wideband meanwhile, chasing "poor
man's lean cruise".
Thread Starter
TECH Regular
Joined: Jan 2007
Posts: 403
Likes: 17
This is a very basic observation and may be way off, but I noticed your long term and short term fuel trims are negative and in some cases rather high.
I wonder if simply multiplying only your long term trims into your VE table while still keeping your short term trims negative would alleviate the problem.
I wonder if simply multiplying only your long term trims into your VE table while still keeping your short term trims negative would alleviate the problem.
Put your scanner in VCM mode and reset fuel trims right before you do a WOT run and see what happens.
You can also turn off Long term fuel trims as well.
Be sure to use VCM control to reset fuel trims. Writing a tune doesn't reset them.
Had that little fact get me on the dyno once......
Ron
You can also turn off Long term fuel trims as well.
Be sure to use VCM control to reset fuel trims. Writing a tune doesn't reset them.
Had that little fact get me on the dyno once......
Ron
Last edited by RonSSNova; Oct 13, 2015 at 05:05 PM.
But in PE, you're back to the VE table x adder, in relation to open loop, continually richer.
Thread Starter
TECH Regular
Joined: Jan 2007
Posts: 403
Likes: 17
op here, i have my wideband wired through the ac pressure switch on my car. I had suspected for a while that my wideband was reading rich. so i logged afr directly from my wideband into logworks. and my afr ratio seems to be very normal when logged into log works, wot afr is 12.7, and steady state afr stays around 14.7, so now I just have to figure out why afr reads rich through hp tuners. I'm actually thinking I have a grounding issue with my pcm
Many people have ground issues (which they then
mistakenly try to correct with a fixed offset, but it
is in fact quite variable, driven by WBO2 heater power
that responds to exhaust temp and ambient cooling).
mistakenly try to correct with a fixed offset, but it
is in fact quite variable, driven by WBO2 heater power
that responds to exhaust temp and ambient cooling).
