O2 SENSOR

[McSmash]

So I have a 95 s14 with a Redtop sr20det. Just picked up this car and am new to the SR. My question is, since it has aftermarket exhaust already on it.. does the SR only have 1 O2 sensor? There's only one coming off the turbo elbow but nothing in the exhaust pipe.. so it only runs on 1 O2 sensor?

[PapaSmurf2k3]

Yeah I believe the red top uses only 1 O2 sensor for air/fuel monitoring, and nothing for catalyst efficiency.

[PapaSmurf2k3]

Also, welcome to NICO!
I like that username

[McSmash]

Thanks man I appreciate the response. I couldn't find any definitive answers. I'm having an O2 bung welded in so I can monitor my a/f ratio.

[PapaSmurf2k3]

Gotcha, so you're going to wire in a wideband O2 sensor and put a gauge somewhere?

[McSmash]

No i was planning on just putting in the gauge. Just so I know what the a/f is. Once I go to build and tune I'll put an actual wideband in.

Another question completely off topic. Seems when I do a dig car will run great up to 7500 through the first 3 gears. As soon as I shift into 4th it's like hitting a wall. Like fuel cut or some kind of limiter. I've noticed this more than once when giving it hell and shifting into 4th. Any ideas on what that could be?

[PapaSmurf2k3]

Might be a factory speed limiter.
And you'll need a wideband O2 to know what your a/f ratio is. Trying to read the narrowband/normal O2 sensor is just going to tell you rich or lean, not how rich or how lean.

[McSmash]

So your saying the stock SR ecu will read off the wideband wire from the O2 sensor of my gauge...?? I thought it would only read the narrowband signal?

[float_6969]

There are two main types of O2 sensors. Narrowband and Wideband. You factory ECU is equipped to read a narrowband. The only type of gauge that you can hook up to read the O2 sensor directly is a Narrowband gauge. Narrowband gauges are the ones with the sweeping lights that don't give any actual numerical readout for the actual AFR. They're basically crap. They just tell you if you're rich, or lean. Not how far rich or lean you are.

A wideband O2 sensor requires a specialized controller to work and can't have it's output signal read directly. If you purchase a wideband O2 gauge kit, it will come with the sensor, controller, and gauge. I prefer Innovate Motorsports products, but any of the name brand ones will work. I think most, if not all, wideband gauge kits now come with an emulated narrowband output. This means you can remove the factory narrowband O2 sensor, install the wideband sensor in it's place, wire everything up, and the wideband kit will have a wire that you can feed into the stock ECU that will provide it with the signal that it needs to see. You'll now have a nice, ACCURATE measurement of the AFR's, and provide the stock ECU the signal it needs to run in closed loop during part throttle conditions.

[PapaSmurf2k3]

Yup, the innovate kits come with a new bung too. You can weld it in and run the wideband stand-alone to the gauge if you don't want to put it where the factory one is.