Installing a air/fuel ratio monitor

[Ed]

I'm thinking about installing an oxygen sensor on my exhaust. Edelbrock has a kit that has everything from the display guage, O2 sensor and the bung that needs to be welded to the exhaust. I want to do this so I can monitor my air/fuel ratio at different RPM's.

Does anyone have any suggestions or thoughts about this?

I currently have the MSA 6-1 jet hot coated headers and a custom 2 1/2 exhaust.

Thanks

Ed

[boostedz]

Well with any air fuel ratio monitor if it isnt wide band you arent really going to get a good reading, standard 1 and 2 wire O2 sensors just give you a generalization at best.

Wide bands run about 350+ for a decent one. Unless you are turbo or are running a really high compression N/A motor I dont really see the need for spending the money on one.

Just my .02

[skyline_stu]

I'm with BOOSTEDZ..... The one you speak of is only a narrow band sensor and should NEVER be relied on to be accurate. Slightly better is a Bosch LSM-11 but the best ones out there are the NTK or Bosch UEGO sensor. I have a motec PLM which uses either sensor and cost about A$2500. Remember, you are not going to get a lab spec unit for a couple of hundred dollars. Some high output engines can be quite sensitive to small changes in fuel delivery.

I recently did some testing of another bosch UEGO sensor Vs the PLM and the results were quite interesting. At light load the 'cheapie' (A$500) was bouncing all over the place but the PLM remained steady. At Medium load I observed AFR's to around +/- 0.4AFR (almost always to the richer side too) but at WOT they were within 0.2AFR. This means that getting full throttle mixtures should be OK but part throttle/transition may be difficult. Both units were tested with the brand new sensors/pickup points swapped and the units recalibrated for each sensor. At least the results were repeatable.

But remember, be sure you know what you are doing if your going to play with fuel curves. ALWAYS start out rich and lean it out, not the other way. Ignition timing will also have an effect on your mixtures and EGT's.

[jmortensen]

He has a restored Z. Not a turbo pushing 25 psi or a 14:1 compression race engine.

Narrowband works fine for carbs on a stockish engine. If you're tuning to the Nth degree, then yeah, a wideband is a lot more accurate. If you have a turbo pushing a lot of boost and the slightest bit of detonation is going to put holes in pistons, then yeah, a wideband is necessary. If you're tuning a set of carbs, a narrowband works surprisingly well.

I've had TWO friends get on the dyno with their L engines running Mikunis and the dyno operator was eating crow about how "useless" the narrowband was. Both said the narrowband followed right along with the wideband the whole time the car was on the dyno, and one did a full day.

Last thing, if you're just using this to tune and you don't want to permanently install the fancy gauge, get a cheapie volt meter and a Bosch one wire narrowband O2. .8V on a narrowband is about 13:1, which is just what you want. Do get a quality O2 sensor. Bosch is what worked for me, and the two guys who surprised their respective dyno operators.

[Cruez]

If you decide on the narrowband O2 sensor, try to source a 4 wire heated unit. It will start producing readings much faster than a single or 2 wire unit.

I have a Bosch unit sitting on my desk to install with a Haltech ECU run 280 Z. I plan on installing it just after the collector. If you wanted to get a little more precise, you could put 2 in, before the exhaust runs into 2 and get readings on 2 banks.

[Ed]

Wow, Thanks for all the info. There is definately more to this than I what I thought. Looks like I have to learn a bit more about this.

Like previously mentioned my engine is mostly stockish. SU's, 270 cam, headers, 9.65:1 compression, mild porting. So the main reason for me wanting to install a sensor would be for tuning purposes. I want to adjust the mixture for best fuel comsumption without burning up the engine.

[Curtis240Z]

I've used the Autometer narrowband and currently using the AEM wideband with the Bosch UEGO sensor. The wideband as previously reported is much more accurate. Is it worth 3 times the price? The choice is yours. I will be converting to triple throttle body injection so the wideband was necessary.

[BlueZee]

Maybe you can try the Australian DIY unit from:

http://www.wbo2.com/

[madkaw]

after reading this I really want to get an analyzer myself

http://www.triumphclub.co.nz/su_carbs.html

But I wandered for tuning the su's if it would be better to find a 4 gas analyzer for more accurate testing across the complete power band.

[madkaw]

Can someone tell me what they paid for their "cheapy" analyzer and where they sourced it from. Something like jmortesen was talking about sounds good.Everytime I look I seem to come up with these 1500$ units. I would like to tune my su's as accuretly as possible since i am putting so much into this motor but also do it myself.

[jmortensen]

I bought my volt meter from Harbor Freight for $6, then bought a Bosch O2 sensor at AutoZone for $30. I bought an O2 bung from an exhaust shop for $5 and had a friend weld it in for me. The single wire O2 grounds to the bung, the positive you have to connect to a wire inside the car. then clamp it to the positive lead on the voltmeter and ground the negative lead. Turn it to the 2V scale and it will show you to three decimal places (not that you need it that exact) the voltage. The refresh rate of the voltmeter is a bit slow, so you need to keep repeating your tests until you feel comfortable with your results.

The Autometer gauge is great but the O2 sensor they supply was a problem for one of the two guys I was citing earlier. He couldn't get a steady voltage reading until he switched to a Bosch sensor. Then everything was peachy.

[SteveK]

Curtis240Z

I will be converting to triple throttle body injection so the wideband was necessary.

Why?? I have been running triple throttle bodies with a narrow band for a year now -- car pulls 250 @ the flywheel and a 13.7 quarter. 99% of the time the sensor is out and unplugged, as the ECU holds true to the map then whats going to make your ratio go out? Running your ECU in closed loop will never yeild the results that direct map will, Get it dyno mapped and leave it.