Ok, so I found one dead thread from '03 about someone putting a resistor (or potentiometer) inline with the narrowband O2 signal going to the ECU. If you adjusted the O2 voltage lower so the ECU "thought" it was running leaner than 14.7 AFR, it should be adjustable for any desired AFR in closed loop.
I run the zeitronix WBO2 setup with the simulated O2 option that is adjustable from 9.5-21.0 AFR which I tested and it does just what its supposed to do quite nicely.
The problem is it would try to achieve that AFR the entire time it was in closed loop. I want something that is boost activated (say 1 or 2psi) that can change the O2 voltage during part-throttle boosting to a richer mixture. I know people try to bump the ECU out of closed loop by tricking the ECU into thinking its opened up at 75-100% but I would rather USE the closed loop setup to my advantage.
Basicly all you need is a map sensor to trigger a relay/transistor which can switch the 02 wire from the standard connection (directly from the sensor to the ECU) or through the resistance circuit.
I cant be the first to think of this so maybe something is already out there?
Jamie- -AUTOMATIC turbo'd 95 Talon ESI@8psi (stock internals)14.0sec=1/4 mile
#99286, "RE: Simulated O2 output" In response to Reply # 0 Feb-26-07 12:46 PM by DarkOne
Originally posted by jack_of_trades Ok, so I found one dead thread from '03 about someone putting a resistor (or potentiometer) inline with the narrowband O2 signal going to the ECU. If you adjusted the O2 voltage lower so the ECU "thought" it was running leaner than 14.7 AFR, it should be adjustable for any desired AFR in closed loop.
No, not really. People do this to fix a CEL from having no cat or no rear O2, not as a tuning tool. For one thing, the ECU doesn't expect the NBo2 output to be linear, and a linear output will cause a CEL. You can't alter that signal with a simple resistor, either, because the output constantly fluctuates between .1v and .9v on a ~14.7:1 stoichiometric A/F range, because that is all the sensor can see. Even if what you're talking about could work, the ECU only allows a +/- 25% adjustment of the base fuel map for the O2 based short term trims. Long term is +/- 11%. Hitting the high or low end of either trim will cause a CEL.
if you've made it this fdar and you're thinking, "A CEL? So what?" then install a MegaSquirt and move on.
______________________________ If a sentence found online has 35% misspellings or greater and includes at least two racially charged expletives, chances are it is a YouTube comment.
'95 Eclipse TurboGS (garage deco) '95 TSi AWD (restoring a survivor) '97 Talon ESi-T (poor impulse control) '99 Eclipse RS-T (daily beater) '13 Evo X (mostly stock) '17 Sienna (Middle Aged Dad Mobile)
#99287, "RE: Simulated O2 output" In response to Reply # 1 Feb-26-07 01:32 PM by jack_of_trades
I don't mean a 'replacement' resistor like a dummy setup for a rear O2, I mean a resistor (more than likely a potentiometer) in series with the O2 output. I know how the narrowband output works on the O2, I just wondered if anyone had tried such a thing. This is basicly what the zeitronix simulated output does when you adjust it via the software settings. It scales up/down the voltage curve. The FMU/S-FMU used generally richens things up just fine, this would just help the ECU from trying to 'fight' the richer AFR it see's.
And like I said, it would only be triggered on when boost is present, so it will be like stock under normal driving conditions.
Jamie- -AUTOMATIC turbo'd 95 Talon ESI@8psi (stock internals)14.0sec=1/4 mile
#99288, "RE: Simulated O2 output" In response to Reply # 2
Originally posted by jack_of_trades And like I said, it would only be triggered on when boost is present, so it will be like stock under normal driving conditions.
Then you're looking in the wrong place. TPS output determines open or closed loop once the O2 warms up. If you want to adjust A/F ratios under part throttle boost, you need to look at a the MAP output and make something to affect the MAP output. We've already done this, however, as evidenced by Corbin's Fool the SAFC mod. O2 trims have very little to do wth anything, really.. the greater adjustment lies elsewhere in playing with things you wouldn't think would adjust fuel, but do.
______________________________ If a sentence found online has 35% misspellings or greater and includes at least two racially charged expletives, chances are it is a YouTube comment.
'95 Eclipse TurboGS (garage deco) '95 TSi AWD (restoring a survivor) '97 Talon ESi-T (poor impulse control) '99 Eclipse RS-T (daily beater) '13 Evo X (mostly stock) '17 Sienna (Middle Aged Dad Mobile)
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