1987 tbi o2 sensor voltage and 3 wire question.

[olllie]

If i where to purchase a 3 wire o2 kit which I need for a ratio gauge.. like this one...

http://www.summitracing.com/parts/atm-2244


Could I use the same signal wire from the gauges more accurate, heated o2 sensor. To run both my ecm input and the ratio gauge, off of one sensor?

I understand the reading is in millivolts 0-1v and just a sweep, but is the voltage output strong enough for my computer to still go into closed loop early with the heated o2. And run the rich/lean gauge properly.

what should i do? run a 3 wire for my ecm, and a second 3 wire down stream for my gauge.. also is running a heated o2 in a stock location a bad idea, being self heated, not too sure if a high heat location is ok for sensor life.

5.7 no cats, stock exhaust manifolds with dual out

thanks

[rfmaster]

I run heated O2 sensors in all my conversions, but $105 for a three wire NBO is a bit steep. AFS-74 can be had from rockauto for $44 + shipping, but you'll have to source wires and weatherpack connectors. The signal from a heated O2 has the same accuracy as from 1-wire NBO, with exception that heated O2 comes-up to operating temperature within 30 seconds vs. several minutes for 1-wire and is not subject to highway coolling. The question if the ECM and ratio gauge can be operated in parallel depends if gauge has a high impedance input buffer. Can not tell without diving into gauge circuitry. You did not post the model and make of your AFR gauge. On some AFR high end gauges there is a buffered output which can be used to drive ECM. On the opposite end of spectrum, a narrow band Auto Meter AFR gauge 2675 installation manual clearly shows that output from o2 can be used to drive ECM and gauge.

http://www.autometer.com/productPDF/0837L.pdf

So it all depends on what you have.
//RF

[olllie]

http://www.summitracing.com/parts/atm-3375

looking at this autometer 3375, guess that was a stupid question.. thanks rfmaster, never thought to look at the instructions lol, just assumed they want you to use the autometer o2 for the gauge to work.

Whats your thoughts on 02 location? do you think 3 wires prefer to be in a cooler location than a none heated sensor?

[rfmaster]

Originally Posted by olllie

http://www.summitracing.com/parts/atm-3375

looking at this autometer 3375, guess that was a stupid question.. thanks rfmaster, never thought to look at the instructions lol, just assumed they want you to use the autometer o2 for the gauge to work.

Whats your thoughts on 02 location? do you think 3 wires prefer to be in a cooler location than a none heated sensor?

In your case, with stock CI exhaust manifolds, I would use stock location. The 3 wire NBO will work just fine there. If you move O2 further away from exhaust chambers a transition delay begins to creep in between when injectors applied or removed extra fuel, combustion process and O2 sensing of the resulting exhaust stream. It is one of many variable ECM code has to deal with. ECM can adapt to a range of variations, but when delta gets to be too large things begin to break down. From practical purposes I run my O2's right at the collector flange of full length headers. This position is some 24 to 36" down stream from stock. No adverse affects or weirdness has been observed.

//RF

[olllie]

Thanks RF that makes perfect sense.