Esoteric O2 sensor question

[Maeda]

I have a...

96 OBDII KA24DE ..connected to..
S13 RS-Enthalpy ECU
S14 OBDII intake mani with emissions stuff deleted
A turbo

I do not have an..
Oxygen Sensor

Is this a bad thing?

Car's been like this for 5 years, and now that i'm redoing a bunch of things, i thought I'd ask if I should change this setup..

[s14SRguy]

depends.

what exactly are your re-doing?

Major Variable.

[Maeda]

depends.

what exactly are your re-doing?

Major Variable.

Good point. :)

I blew my turbo, and the motor is a little low on compression, so i'm rebuilding it with some new guts.

I'm keeping the ecu since i will not be changing turbo/injectors/etc.

[s14SRguy]

i don't think so, if all is running fine how it is and you only do internals i don't see why not

O2 sensor only tells the ecu how much oxygen is in the exhaust for emission reasons. If your ecu is set for an emissions delete I don't see how that would pose a problem.

hopefully someone else can chime in on this to confirm

[Maeda]

I know the O2 is read for the closed loop part of the map.. partial throttle mid/low rpms ranges, but I would like somebody to chime in with a bit more specific insight..

[racepar1]

Why don't you have an O2 sensor???

The ECU uses the O2 for correcting the A/F ratio in closed loop. Without an O2 the computer has no provision for monitoring the A/F ratio. YES you SHOULD have an O2 sensor. YES is MAY help the engine run a little bit better and get a little better fuel mileage.

Since you've got some crock-cobbled together setup using an S13 ECU and a bunch of other mis-matched bullshit it's going to make things complicated. You need to use an S13 sensor with that ECU. If you're still using the S14 wiring harness then the O2 plug will not be the same and you'll have to wire-in the S13 sensor yourself. You might be able to have the ECU re-flased to work CORRECTLY with your S14 as well...

[Maeda]

Why don't you have an O2 sensor???

The ECU uses the O2 for correcting the A/F ratio in closed loop. Without an O2 the computer has no provision for monitoring the A/F ratio. YES you SHOULD have an O2 sensor. YES is MAY help the engine run a little bit better and get a little better fuel mileage.

Since you've got some crock-cobbled together setup using an S13 ECU and a bunch of other mis-matched bullshit it's going to make things complicated. You need to use an S13 sensor with that ECU. If you're still using the S14 wiring harness then the O2 plug will not be the same and you'll have to wire-in the S13 sensor yourself. You might be able to have the ECU re-flased to work CORRECTLY with your S14 as well...

In my defense this is a KA-T setup that was built in 2002-2003 so there weren't exactly many options that made sense at that time. It was pretty much SAFC or Enthalpy or Wolf S13 ECU or RRFPR (seriously)

I think i'm just going to scrap it all and build myself a megasquirt and use a wideband O2, but if I don't go that route, i'll chop my engine harness and wire it to the S13 plug, and wire in the S13 O2 sensor.

I love living in the future!

[racepar1]

In my defense this is a KA-T setup that was built in 2002-2003 so there weren't exactly many options that made sense at that time. It was pretty much SAFC or Enthalpy or Wolf S13 ECU or RRFPR (seriously)

I think i'm just going to scrap it all and build myself a megasquirt and use a wideband O2, but if I don't go that route, i'll chop my engine harness and wire it to the S13 plug, and wire in the S13 O2 sensor.

I love living in the future!

Honestly the main issue is that you're using an S13 ECU on an S14 engine. You could just buy an enthalpy S14 ECU now-a-days. The electronics between the S13 and S14 dualcams are similar enough to work together (apparently), but not close enough to work perfectly.

[Maeda]

"Most of the time it does not make even the slightest of difference"
Straight from the horse.

[Kingtal0n]

you can use any narrowband oxygen sensor from any vehicle (just match the thread). Go into pep boys and ask to see the oxygen sensors. pull open boxes 1 at a time until you find the 1-wire sensors. Then price check them and buy the one thats $20 or less.

Use that sensor in your engine, just connect the single signal wire to the signal wire at the ECU.

Done

[Mikester]

"Most of the time it does not make even the slightest of difference"
Straight from the horse.

I don't run an O2 sensr... I have always had it turned off (option on PFC/Commander) since the 180SX in relatively stock config- All the way through the subsequent and current tunes. I'm not sure if it actually switches loops using separate logic based on temperatures or other such parameters; but the motor has always run fine.

Whoever the horse is, I absolutely agree... even though I don't know the ins/outs.

[Kingtal0n]

Well heres where the black sheep comes in and spills details all over the place like a slippery coat of fatty acids

Intimate details of oxygen sensor operation:
1: placement & temperature
where is the sensor? What temperature is it? As the temperature of the sensor changes, the reported voltage will also change. Also, placement matters, especially to ECU's without adjustable transient delay settings. The farther from the head, the slower the sensor will react, which means the ECU may tend to overcompensate.

2: injector size
most computers and closed loop operation can not adjust for larger than factory injectors well, and as with placement being farther, the larger the injector, the more overcompensation the ECU will generally commit.

Temperature, placement, and injector size all play a role in how well a random narrowband O2 sensor will function. Some computers have the ability to adjust for larger injectors (AEM and Haltech for instance) as well as transient delay. But the power FC and factory computer can not.

There is, however, an option in the power FC (accessed via data-logit) that allows the user to specify WHEN to use closed loop operation. I find in most engines with large injectors, long duration camshafts, and far placement oxygen sensors, will still benefit from closed loop operation during 2800RPM+ highway cruise situations.

Furthermore, new wideband technology is available to us that uses "narrowband simulators" that allow the wideband to be used as a narrowband, and with CUSTOMIZABLE VOLTAGE outputs, this makes the operation of closed loop a very practical and desirable choice for all engines. By customizing the exact voltages of lean and rich air fuel ratios, we can "fix" the aspects of transient delay and large injectors by widening the scale of voltage for various air fuel ratios, thus lending a helping hand to computers such as the power FC which do not have any options or settings for transient delay or large injectors.