A/F Ratio Gauge??

[Gixxer750]

Looking for an air/fuel ratio gauge from Autometer, but can't seem to find one on their web site. Anyone know a part number or have a link??

 

[shttygtstang]

http://motors.search.ebay.com/air-f...6catrefQ3DC6QQsosortpropertyZ2QQsosortorderZ2 ebay go for it

 

[ECU5.0]

go to truckperformance.com they have a lot of good stuff and usually have some good sales on gauges

 

[SLiM JiM 156]

Unless you want it for the pretty lights, dont buy it its a waste of money.. trust me, I have one..

 

[iwashmycar]

Unless you want it for the pretty lights, dont buy it its a waste of money.. trust me, I have one..

 

[cmozez]

I'm confused,, do they not work? Is it not better than not having one at all?

 

[EMW150]

You'd be better off with an Exhaust temp gauge. If you want to tune with it be sure to get the Competition type "K" thermocouple. I have the Autometer setup and it gives instant readings - great for tuning.

 

[jaidedeye]

spend the 300-400 bucks and get yourself a wideband...now thats worth it to me when a guage reads the A/F ratio down to the decimal....also make makes tuning at home a little easier

 

[Michael Yount]

These guys are steering you in the right direction. Any a/f fuel gauge that's designed to work with the factory O2 sensor won't help you much. The factory sensor is accurate at reading the ratio only in a VERY narrow band right around stoichiometric (14.7:1) -- once you get much past a 1/2 point to a point either side of that, they're not designed to accurately measure the change. So, as someone else said, you get lots of lights, but they really won't tell you much.

You need a gauge designed to take it's feed off of a new, separately installed (exh. shop welds in a new bung) wide band sensor. Those sensors can accurately read from around 9:1 to 18:1 - and you'll get a good sense of what your actual a/f is. Alternatively, exhaust gas temperature readings will also give you a good sense of what's going on in the chamber - but you need some data on what acceptable/good/bad readings are, and why. Perhaps my buddy EMW can give us a bit of tutorial on what kind of temps to look for under what conditions. I have some sense of it for turbo-charged diesel engines and 2-strokes, but not for 4-stroke gasoline engines.

 

[EMW150]

Well, on my combo I look for readings at about 1400 or 1450 degrees at WOT. There are several things that can effect the temp and lead you in the wrong direction if you're not familiar with how the gauge works. For example, if you run your timing retarted it will read high on the EGT because part of the mixture is being burned in the header tube rather than the combustion chamber. So a person who is running their timing retarded sees a high EGT reading he may think he's running lean and richen the mixture which will make matters even worse. It takes some time to figure out exactly what your car likes and how different things effect the readings, but once the timing is dialed in where it should be, you can feel safe using it for controlling your mixture. If I was running at the track and my MPH were down and the EGT was around 1300, I'd feel safe knocking it down a jet size or so to lean it out and if the outdoor temps drop later in the day you can keep an eye on it to make sure you don't go too lean. Make sense?

 

[Michael Yount]

That's helpful for me - learned a little bit there. I do know that where the probe is placed in the system has an impact as well - obviously you have issues of 1) retarded mixtures still burning in the system outside the chamber vs. cooling of the stream the further away from the chamber. The kind of duty the engine is seeing is an issue as well. Judging by your sig - your engine is seeing these kinds of temps for a few seconds. In the case of, for example, a PowerStroke diesel pulling a 10,000 lb load up a mountain - they could see max temps for 2-10 minutes, or more. 1400F-1450F for that time period would turn the turbine blades on the exhaust side red hot and likely cause their shape to change - ruining the turbo. They strongly recommend 1300-1350F as an upper limit to avoid turbo damage. Usually on the simpler two strokes, excessive temps usually just lead to a seized piston -- and if you're lucky when it cools down, you jet it one size richer and never have a problem again.

So as EMW wisely states - you have to take some time with your configuration and figure out what the data is actually telling you.

 

[88stangmangt]

ya autometers a/f ratio guage are for honda's who like the pretty lights.

 

[Michael Yount]

Play nice 88 - there are plenty of serious Honda boys and girls out there, and plenty of Stangs with neon underneath....you can't paint them all with one brush.

 

[EMW150]

I run my probe 1" from the flange at the head. You're right, that is definately a big factor in the readings you'll see. Forgot to mention that. I'm surprised the turbo'd diesel's don't run any higher exhaust temp than that. I would have guessed them higher.

 

[Michael Yount]

I think if the duration of the temps were shorter, you might see higher recommendations, but they tend to work hard for much longer durations than drag cars do. I suspect that's the culprit. Combined with the fact that the toll taken at high temps is cumulative - when you do damage, it doesn't fix itself when the temps come back down. What's damaged usually stays damaged.