LilJayV10

iTrader: (5)

I am ordering a dual gauge pod for my bird, since no one seems to have a three pod right now and was wanting to put fuel pressure in one, and A/F meter in the other to tell if its running lean/rich or not. A buddy of mine, who is a mustang guy, go figure swears that they are inaccurate and not worth the money, even though he has one on his car. Does anyone have one? and if so what are your experiences? Thanks. Jason

Morley

I just installed one in my car from Dakota Digital, it reads the actual mv signal that the O2 sensor sends to the ECM and it reads the same as WinALDL. But...all this tells you is weather you are running rich or lean but not HOW rich or lean you are running.

LilJayV10

iTrader: (5)

but with the info it gives you, you can jet accordingly right?

Morley

To a degree, yes, but for computer controlled carbs a WB would be better.

ronterry

I'm going to do one myself. I purchased a Nordskod from Summit, and picked up a 3 wire heated O2 today. Total cost 85 bucks.

I'm trying to get in the ball park for jetting my carb also, but I'm not using it to fine tune - the plug help with that.

The only reason I'm even doing this, is because the Hooker Headers had a bung already welded on. All I needed to do was drill the hole.


Ron

LilJayV10

iTrader: (5)

so they are "kinda" accurate then? and idea who makes the best one? I know autometer does, and i think cyberdyne but not for sure.

Morley

As I said, they will tell you if you're running rich or lean but not how much of either.

MorgRS

The O2 sensors are great tools, especially with a vaccum and EGT sensors to give you the whole picture. Here is a site with some good dynamic testing proceedures. http://www.bob2000.com/carb.htm
This should help.

ronterry

I tell you right off the bat, I hooked mine up and right away I solved my slight bog when flooring it.
Everytime a floored it the gauge went lean, hmmm sounds like my step up spring is to weak causing the the lean spot. Put on a stiffer spring, and no more lean spot. I know I could use a vacuum gauge for that, but it was neat to see the cause & effect.

I'll be tuning this weekend

I still back up my results by reading the plugs.


You can read how rich or lean to a point. Your not going to be able to go, 'yea it's @ 12.4:1 @ WOT', but you can to a certain resolution say 'It's a little lean, little more lean, or real lean' or eye burning rich in my case

BTW: With my heated O2 I get reading within a minute after starting.

Ron

Inwo

If you buy one that doesn't totally suck then yes it will indeed tell you how much of either. There's an electronic one from Autometer that you run in line with your O2 sensor (weld in a bung if you don't have one geez) and it tells you precisely how much of either. I have a 3-wire O2 sensor, no computer, and it works perfectly and tells me EXACTLY how much the a/f ratio drops off/raises when I romp on it. No bs "idiot light" for me thanks!

Morley

This is the ONLY O2 meter that will tell you how rich or lean you are running http://www.diy-wb.com/ , all of the others are a simple switching O2 sensor and only tell rich or lean, not how much of either.

paul_huryk

That is not entirely true. I have the Edelbrock A/F Meter and it shows the ratio from 12.0 to 15.0 in 0.5 increments. Summit and Jegs carry it for $125 for the kit.

I will say that the meter is the best tuning investment you can make on a street car (EGT sensors aren't streetable).

The tuning ability on a carb car is tremendous: you can figure from the reading whether the car is lean or rich all the time and make adjustments to compensate (for weather, temperature, or altitude). I had to drop my secondary hanger four steps to get the proper ratio, the car picked up about 15lbs o torque, enough to feel.

With a FI car, you have no adjustments with factory FI other than the fuel pressure, not all that great, but a start. If you have DFI or other controller that can vary injector pulsewidth, you can tune it the same as a carb.

It is more than worth the $125 and the minimal labor involved.

LilJayV10

iTrader: (5)

well, i was planning on getting one that just doesnt totally suck So the autometer and edelcock ones are ok? and should I use a 3wire heated )2 sensor, my hooker LT have a place for the 02. I thought this thing might help me better dail in my car. Thanks for the replies

ronterry

Don't forget to check out these guys. They've got some good reviews from magizines.

http://www.intellitronix.com/airfuel.html

The one I got was the M7009, for test & tune. If I wanted to mount a looker than the 70140 is cool as hell.

Their O2 sensors are a bit pricey($70), so I got a Bosch 3 wire for 45 bucks @ Checker. Stay clear of the 4 wire, cause the forth wire is a OBD2 thing, and your just going to pay extra for a hanging wire.

If you decide on your own over the counter O2, hook up the two SAME color(normaly white) wires to a switch pos. & neg (dosen't matter which order), and the different color(normaly black) wire goes to the gauge.

I think the gauge manufactures mark up stock heated O2's ????

Good Luck,

Ron

LilJayV10

iTrader: (5)

does the edelbrock one use wideband? how does it know exactly what the a/f is? If it works that way, seems to me that would be better than the rich or lean lights. even though those are cool. thanks.

ronterry

Nope, it uses a standard heated O2.

It doesn't know the exact A/F, thats why it only has like 5 leds.

Sorry 'LilJayV10' your just not going to get a exacting tool unless you dish out a couple grand for a emission analyser.

The wideband deal has more resolution, but mostly on the lean side, and most of it outside the normal max of 18:1.

Ron

LilJayV10

iTrader: (5)

I understand that, I was trying to get a better idea of how they worked and which ones were better.

Grim Reaper

You guys BETTER listen to Morley. The ONLY O2 sensor that you can use for tuning is a Wide Band, plain and simple.

While you are "cruising" in Closed Loop, all the stock O2 sensor does is "switch" above and below 450 mV - attempting to attain an overall average of 14.7:1. But what you see (I have a scan too so I see this ALL the time), is "mV readings above or below 450 mV. This is by GM's design. The O2 sensor used in our cars is simply a "switching device". It was NEVER designed to be used as ANYTHING but a "switching device".

Some people (in the old days when they didn't know better) advocated using the O2 reading while operating in WOT. (I did too, until I learnt more).

We get people on the DIY Prom Board ALL THE TIME, asking "What mVs should I run in WOT with the stock O2 sensor" and the answer is always the same "you cannot rely on the stock O2 sensor - get a WB or read spark plugs, but forget the stock O2 sensor".

Waste your money as you wish, but you are just wasting your money if it's NOT a WB O2 sensor. End of story.

DAVECS1

iTrader: (2)

I understand the concept of O2 being a switching mechanism and the ability of a WB O2 for tuning. I do not think a guage hooked up to a regular switching O2 is a waste. Though you do not know how much lean or rich you are you can make small adjustments inorder to make your switching O2 switch less. The less it switchs the closer you are to stoichemetric. Correct?

Morley

Kind of, it all depends on the computer and its programming and "where" you are tuning.

DAVECS1

iTrader: (2)

Well I am assuming the problem area is within BLM correction range.

Example: While driving around you feel the car bog from 2800-3500. Looking up at the gauge you see it is jumping from stoic to lean.

Couldn't you then go into your tables and ad a little fuel from 2800-3500 and 40-60 KPA and see if the car picks up and the gauge levels out?

JMatlock88

For those of you who have a a/f guage, how are you reading yours? Mine just sits there and bounces back and forth. As far as I'm concerned, Just paid $60 for an interior christmas light. Ignorance is bliss i guess. (BTW mine's a Norskog bar led guage)

DAVECS1

iTrader: (2)

Would a VAC gauge be? more benificial

Steve89GTA

I have a VAC guage hooked up in my car. It's great for conserving fuel..i.e....you can see exactly how much gas you're giving her with your right foot. Other than that, I'm not too keen on it's readings.
It reads 21-22 in Hg at idle which people are impressed with. I'm guessing it's a good thing.

ronterry

My A/F gauge dosn't bounce around, cause of the simple fact that I don't have a computer running the show - Hince why we have the gauge, or at least trying to use it as a crude tuning are CARB tool.

Ron

DAVECS1

iTrader: (2)

Let me explain myself on the VAC gauge statement. I assume most of you have an A/F to help you tune. And some of us are under the impression that it will enable you to view the engines mixture values at different RPMs assuming you have a TACH.

With a VAC gauge you wouldn't know if you were rich or lean, but you would have a good idea were the tuning would need to be done. Take for example the VAC gauge running 30 KPA at idle. This means the cars throttle range is from 30-100Kpa. 100 being full throttle. So your going down the road and you ease into the throttle to speed up and you notice a stumble. I personally would try to recreate the stumble and take note of the TACH and VAC gauge. This will tell exactly were you need to tune. So lets say the TACH was at 3600 and the VAC read 70 KPA. This tells you that at 3600 and 3/4 throttle you need to adjust the mixture. I would start by going rich and if that doesn't help go the other way. This would be easy for prom burners, for carbed guys it will take getting familiar with your carb to findout what changes will correspond to different throttle positions

Apeiron

It sounds like you're talking about absolute manifold pressure, not manifold vacuum.

86iroctpi

Please clarify this for me. An A/F guage will do no good on a fuel injected vehicle unless it is used with a wide band O2 sensor? And the only place to get a relatively in-expensive WB-O2 sensor is to make your own as described at DIY-WB.com. Is this correct?

Morley

Correct. However a regular O2 sensor/guage can tell you IF your computer is able to maintain the correct A/F raito. If your engine is running VERY rich or lean, the computer won't be able to maintain its programmed A/F raito and this will reflect in an O2 guage, but you won't be able to tell just how rich or lean it is actually running.

DAVECS1

iTrader: (2)

Absolute manifold pressure, vacuume are both just a measure of the difference in pressure in the intake manifold. It is this difference that feeds a signal to your carb or SPEED DENSITY fuel injection.

1 inHg = 3.39 Kpa

fulo

I have th Auto Gage A/F, TACH, Vacuum Gage... I am very satisfied wiht the products.

Ragarding hte A/F meter... they are NOT ACCURATE, and they only measure either extreme of the "Spectrum". When your mix is Stoic, that mean that is on Best possible range...

This happend because you cannot measure conbustion accurately... Cobustion is affected by many variables (temp, Baro. Presssure, Air Flow, Combustion, air/ oxygen ration,etc) Cobustion is a very CHAOTIC PROCESS...

What has been concluded (for sake of measurement) is that combustion happends in a range, were it either goes lean,stoich, rich. I kind like the white, gray and black spectrum.. there is allot in the gray (stoich).

Having said this, I have one, and It HELP me to calibrate my carburetor... its also a great way to keep an eye on mixture.

Besides, if you cannot afford one, they are pretty need.. specially AUTOGAGE

Hope this helps

Apeiron

Absolute pressure and gauge vacuum are subtly different, actually. Gauge vacuum compares pressure with the outside atmosphere, absolute pressure compares pressure with an absolute vacuum.

DAVECS1

iTrader: (2)

Your gauge and MAP sensor both compare the pressure differential between your manifold and the atmosphere. I used KPA because that is the units used when calibrating your Volumetric Effiency tables inside a speed density ECM.

Apeiron

This is getting off topic but no, the MAP sensor doesn't compare to the atmosphere, that's why it's called absolute pressure.

Grim Reaper

Actually it does. At WOT at sea level, you will see around 100 Kpa on the MAP sensor. But at the Pennask Summit on the Coquihalla Connector, you won't even seen 80 Kpa @ WOT on the MAP sensor. This is due to the lower atomospheric pressure caused by the eleveation.

Also, your idle Kpas are affected too. At top of a mountain pass, your Kpas at idle are lower than they are at sea level. I noticed a 10 Kpa drop on my MAP sensor when idling.

Apeiron

That's not comparing with atmospheric pressure, that's being affected by atmospheric pressure.

MAP sensor readings at WOT will vary with altitude because it measures absolute pressure in the manifold. That's why speed-density systems have to have a separate BARO sensor, or use the MAP sensor to read the barometric pressure before the car starts. I've heard stories about problems with early GM speed-density systems being driven over high mountains where the atmospheric pressure changed significantly but the ECM had no way to tell and performance was affected. Newer systems supposedly reset the barometeric pressure at WOT to correct this.

The vacuum gauge will read zero (or close enough) at WOT at any altitude because it reads how much less pressure is the manifold than in the atmosphere.

Grim Reaper

Agreed. And yes, a vacuum guage will always read "near zero" at WOT regardless of elevation. On the issue of the SD system reading the baro on startup, I would have to read the code of the 7730 to see exactly what it does. Winter project.

What would be interesting is what a vacuum guage would read (say at idle) at sea level and then at 6,000 feet. I've always wanted to do a study on it as I suspect it reads less at higher elevation because the air itself is less dense.

DAVECS1

iTrader: (2)

Well I agree with what you all have to say. It is kind of like agruing the pronounciation of tomato. So lets whip this discussion back on track.

1. Would it be more benificial to have a VAC gauge or A/F ratio gauge.

2. Can you tell if it is lean or rich or just when it is switching to correct for the A/F?

3. Maybe exhaust gas temps might be a good indicator of rich lean conditions.

Morley

The easiest and best way to tell a rich or lean condition is the Wide Band O2 sensor/meter.

LilJayV10

iTrader: (5)

we've been through this, those are expensive. we are talking about the basic a/f gauges.

Morley

That may be, but as the old saying goes "You get what you pay for"
None of those others alone will do what you want, maybe with 2 or 3 of them together you'd be able to get a better idea of what your state of tune is.

Apeiron

I get somewhere around 2-4 inHg more vacuum at cruise in Kelowna than I did in Calgary.

drive it

iTrader: (1)

What would be interesting is what a vacuum guage would read (say at idle) at sea level and then at 6,000 feet. I've always wanted to do a study on it as I suspect it reads less at higher elevation because the air itself is less dense. [/B][/QUOTE]
I get 11 to 12 at home (7000ft elevation) and at near sea level it's 17 to 18 at idle-so yup, does make a big diff! I kept looking for a vac leak at first after the new engine....

LilJayV10

iTrader: (5)

how close are the a/f gauges any idea? are they close, well maybe, or why even bother?

Grim Reaper

End of story.

Inwo

So basically a 3 wire 02 sensor connected to an autometer gauge is simply switching back and forth and that whole "measuring the resistance" or whatever is just bs? Man, someone better tell autometer that they're selling junk and that all of those morons with non-cc carbs should get a clue because it's not helpful at all! I mean obviously the stock three wire heated oxygen sensors on the non-cc carbs that came on all the thirdgens are worthless, and the way the gauge reacts appropriately to changes in jetting is just bs, BS!!!!!!!! Geez, someone buy these guys a clue! Geez their fuel injected carbeurated cars with the stock headers and stock 3" catback sans cat obviously doesn't need any worthless tuning help, the best way is to check plugs because as we all know plugs are the only way to tune and all others are worthless and any assistance from something that will tell you what your mixture is doing is just a pointless act of futility.
Obviously because it's no good in fuel injected applications it's totally worthless for everyone in every circumstance.

Grim Reaper

Yes, that's exactly right. In spite of your apparent sarcasm, I will reply. People keep forgetting that the stock O2 sensor was derived for one and only one purpose, for the ECM to alternate between "rich and lean" to arrive at 14.7:1. Nothing else.

Along the way, in the 1980s, people with scan tools noticed the volt readings and started to use it for tuning purposes. However, guys noticed that there was "no magic number". People would say .88-.92 volts, but some would find themselves rich and other lean at those values. They just didn't seem to hold true universally. Also, it only measures one side of the engine.

Then some engineering types pointed out the "graph" of how a stock "switching type" O2 sensor worked and operated and then it is REALLY apparant why a "switching type" O2 sensor is worthless for WOT tuning.

As for Autometer (and others) selling worthless products. Well, surprise, surprise, surprise. Gee, it's just like the "relocated MAT" sensor for a MAF car...another completely useless product because the MAT sensor does NOTHING on a MAF car other than trigger the EGR....air temp is measured by the MAF itself.

Better yet, what about a Tornado?

No their are alternatives to "plug readings", it's called a WB O2 sensor. Now THAT can do basically ALL your tuning. In fact, a few guys have found that even though their stock O2 sensor and ECM says they are running at 14.7:1 on their scan tool (and in closed loop), they found they were runnign at 16:1.

They had to reprogram the eprom to make the ECM run richer so they could get it to run at 14.7:1...and it solved a lot of driveability problems.

Kevin G

An A/F gauge is a good thing to have to make sure there is not anything major wrong with your car. I ran a blower and had it tuned using a wideband on a dyno. Once I had it tuned properly, I used a digital A/F meter in the car to make sure i was not running way lean or rich on the street. It can work well for that reason. It saved my motor once when my fuel filter clogged, and i started hittin lean. Sensor let me know to take the car home and not run it.

A Wideband setup is much more accurate than a conventional o2 sensor in a GM car. But I sure would not call it useles either. It is just another tool to keep an eye on whats going on for me. Back in the day when I ran a junk FMU, the stock sensor on my 94 Z-28 actually was pretty accurate, when comparing my tuning to the wide band dyno tune. For tuning though, you cannot beat a WB.

DAVECS1

iTrader: (2)

I have to agree with KevinG. It is a great way to keep an eye on things. I have a SD TPI and I run one but I do not use the O2 sensor the computer is using. This will cause the guage to fluctuate erratically as the ECM switches from rich to lean all the time. I used a heated one from a ZR1 in my y-pipe. Just for yucks I tried thre different chips I had burned. I new they each had a lean or rich spot in them and sure enough the gauge would reflect this. I am using the Nordskog gauge. Like Kevin said you can't really tune by it but it is a good indicator something may be wrong.

LilJayV10

iTrader: (5)

ok question, if an a/f gauge is inaccurate because all it does is switch from lean/rich, why do they use them for emmisions purposes if they are that innacurate, and why dont all vehicle manufacturs use WB O2? is it because the a/f gauge is measuring one thing, and an O2 sensor for emmisions is measuring a different one? But isnt efficency efficency? This might have already been answered but I might have missed it. I apperciate all the replys.