A/F/R gauge for tuning

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Dave999 said:
ive got an AEM uego in summary useful as hell...like it.. been in ten years, still like it.

bung in exhaust/ mine is at the junction of the headers, needs to be in the right position
i.e 10* or more north of a horizonatal diameter-line of the pipe cross section. i.e at 10, 11 12, 1, 2 o'clock not 9 not 3 and not anywhere else.
so the thing can't fill up with condensation and burn out.
In some cases the sender and its plug are a calibrated part you can't just stick another sender into the plug the plug had a resistor etched away by a laser as they tuned the sensor during manufacture... this is a feature of some 3 and 4 wire wide band sensors and not a feature of some others. if it looks like 2 plugs, it is.... one of them stays with the sender. AEM will say in the intructions what you got... probably Bosch 4 wire.

They will die quick if you use AVGAS or leaded race fuel.

i agree with what has been said if your tune is miles out the thing will confuse the hell out of you.

sender too close to the head will read rich on overlap at some rpm or other and you risk over heating it or drownng it in fuel.
too far away leads to signal delay and if you have no muffler at all, air can be drawn in and it will read lean at some rpm or other
somewhere between the front foot well and the rear footwell on a car with mufflers works ok. its a compromise its not ideal.

OEMs put them up front closer to the head... but they know what they are doing... its an ecu controlled car and the chances of flames lapping at the sensor due to seroiusly wrong timeing or serious over fueling are low.

misfire/flat spot what caused it? wet plugs too rich the thing reads rich
misfire/flat spot what caused it? too lean, or marginal ignition system/plugs well the thing will read rich bceause you didn't burn any of the charge and it will continue to read rich until you drive through the flat spot. it may or may not go lean after that . It depends on if your mixture is now correct for your current RPM and igntion advance. but you will think its rich and lean it out even though it was a lean flat spot and it will then pig pong between rich and lean like you would not believe over a much wider rpm... :)

you just have to get your ears in tune...... and you nose.....

the wrong heat range of plugs will have you chasing your tail.

the car needs to run and drive for it to be of use

The AEM has an inteface on the back the can outpout a voltage that can be used in place of a lambda sensor output into an ECU of any type that has a user defined or lambda table provided you can customise range. or you can connect it to a data logger thats plumbed into igntion


if you tune to 14.7
your car won't run well at all it might if it was a heart shaped, pent roof 4 valve combsution chamber in an ally headed four pot withn VVT but not a chunky old v8

aim for 12.5 to 13.5 with foot down
no probs if it goes north of 14.7 up to 15-16 or so on cruise or when you lift off. your advance curve or ideally vacuum advance or MAP should cater for that.

a wheel nut off a vintage rover makes a good bung for the exhaust :) robust weldable and same thread but most gauges come with one. :)

set idle then check guage, should be 13.5 13.7 14 or some such
move onto progression WOT then check cruise

any issues you have will probably stem from plugs or ingition curve. an Igntion system that just can't cut it, once the car's tune gets into the good place is often a problem. previously you were running around rich all over putting out the flame slightly as it were

i.e better mixture = more power = faster exhaust gas speed= more extraction effect= bigger inlet charge= higher combustion chamber pressure at some rpm just as it gets on cam = intermittent failure of igntion system in some way, that maybe you can feel or hear or maybe not. but your lambda guage is going suddenly rich for 200-500 rpm

resulting in
Daft lambda gauge readings = doing the wrong thing to fix the problem= having to stop and have a beer and try again tomorrow

I found i suddenly had more valuble information and i was easily lead by the erroneous crap that is also shown..becasue i never knew about it before.

they are a great and a useful tool once you know about the stumbling blocks
and of course the output when used by an ECU is sampled and filtered and processed to cater for anomolous results when everything is badly out of bounds....

your eyes can't do that,

So you tune it as you always did and use this to check results, not the other way around. this is for the last 20% the tweaking. and a useful warning system on track or at dyno.. if the gauge is all red half way through a pull.........ssssssstttttttop before you melt a piston

Dave
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The old pump gasoline that was 100% gasoline or new non oxygenated fuels are stoichiometric at about 14.7:1. Now we add ethanol to the gasoline and we add O2 molecules to the mix. Watch Matt with GT350 Garage videos on fuel as he does a good job of explaining the whole deal. E100 is stiochiometric around 10:1. So an E10 fuel is stiochiometric about 14.1:1. This is commonly available pump gas these days. Power fuel ratio should be 11.5:1 to 12:1.
When I looked at the Edelbrock AVS2 650 calibration (jets and metering rods) as compared to the older Performer 600 calibration, they appear to be much richer. It was after watching Matt explain fuel ratios and alcohols that my understanding came. Edelbrock is setting the factory calibration with oxygenated fuels in mind. Edelbrock tech recommended that when installing the AVS2 annular boosters in the primaries of my Performer 600, to start with the AVS2 factory calibration and tune from there.
 
92b said:
Not exactly ABA testing going on there. Might be hard to sort out what caused what. Are you saying that overlap caused the o2 sensor th read rich?
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That is correct. Now remember that sensor was an input fuel trim to an ECM. This was an early step in better fuel management that was only used for a year or two. Then we had TBI for a bit longer.
What was happening was the overlap allowed raw fuel to escape out the exhaust valve. Whatever happened to the chemistry of the exhaust the fuel displaced O2 at the sensor. This article is from the latter '80's so understanding of electronic controls was not as well understood as today.
 
gtxdude said:
Any one use a Air Fuel gauge for tuning at home? And if so, is it worth it? Last question, is there one that you recommend that's not super expensive that works?
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My answer is yes and no, yes and no, can't answer without knowing your definition of super expensive.
  • Yes but its a logger not a gage.
  • Yes it was worth it, but now I've learned that a lot of tuning can be done without it.
  • Depending on your needs or interest, it may be more economical to spend a 1/2 day or at least an hour two on a dyno, o go to a drag strip. Advantage of the dyno will be that even a tail pipe sniffer can be used to see if AFR is drifting due to over emulsion or incorrect HSAB to jet relationship. The scale may need to be expanded a but the trend will be there.
Lots of discussion on the gages which should provide some insight into the uses and issues.

The real question is what do you want it to do?
If you are aiming for air fuel ratios, then you've been misled.
What a WBO2 does is give you references points to observe changes.
Then those readings can be compared with changes in performance that can be compared with a particular change in fuel to air intake.

A gage allows observation of steady conditions.
A logger allows observation of both steady and changing conditions in conjunction with other inputs such as rpm, vacuum (MAP), throttle position, etc.

In addition to the learning curve on the tuning side, there is learning curve for the hardware setup, and for a logger, the software.

Drag strip examples of using a WBO2 and logger starting at this post:
Proform 850 dialing it in closer

Some Dyno and street examples first cpouple of pages here
100 cfm more with anular and downleg boosters can't beat AFR

Finally, whatever you chose to do, Tune for Performance.
Wideband UEGO Air/Fuel Sensor
 
Dale Davies said:
That is correct. Now remember that sensor was an input fuel trim to an ECM. This was an early step in better fuel management that was only used for a year or two. Then we had TBI for a bit longer.
What was happening was the overlap allowed raw fuel to escape out the exhaust valve. Whatever happened to the chemistry of the exhaust the fuel displaced O2 at the sensor. This article is from the latter '80's so understanding of electronic controls was not as well understood as today.
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I'm not going to say that is impossible but I think with the information provided that conclusion could be a bit of a leap. Unless you have more data to support that conclusion that wasn't in the post. How was it determined that the motor was lean to begin with? On the first carb did they try unpluging the mixture control solenoid and jetting the carb up to confirm that the motor was lean? Were they using et as their measuring stick for improvement? More details on this test please.
 
92b said:
I'm not going to say that is impossible but I think with the information provided that conclusion could be a bit of a leap. Unless you have more data to support that conclusion that wasn't in the post. How was it determined that the motor was lean to begin with? On the first carb did they try unpluging the mixture control solenoid and jetting the carb up to confirm that the motor was lean? Were they using et as their measuring stick for improvement? More details on this test please.
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I can not remember all the details, but the engine would lay over like it was lean and the plugs confirmed. Jetting, drilling air bleeds or whatever they did had no effect due to the computer correction. Unplugging the fuel solenoid; I have no idea if it would go rich or lean. This was all in the articles documenting the build.
I would have had the articles if my ex weapon had not tossed a bunch of my books and magzines during separation.
My understanding of the Holley replacement was that it was like the Edelbrock Q Jet knockoffs, but it had the feedback feature built in like the original. If they had not modified crap out of the original Q Jet, it probably would have functioned with the shorter Engle cam. Remember that the early EFI systems all had PROM chips which had to be replaced with another with a tune burned on it. PROM; Programmable Read Only Memory. Later came the EEPROM chips; Electronically Eraseable .... These did not perform anywhere like the current flash programmable ECU's in use today.
 
Dale Davies said:
The old pump gasoline that was 100% gasoline or new non oxygenated fuels are stoichiometric at about 14.7:1. Now we add ethanol to the gasoline and we add O2 molecules to the mix. Watch Matt with GT350 Garage videos on fuel as he does a good job of explaining the whole deal. E100 is stiochiometric around 10:1. So an E10 fuel is stiochiometric about 14.1:1. This is commonly available pump gas these days. Power fuel ratio should be 11.5:1 to 12:1.
When I looked at the Edelbrock AVS2 650 calibration (jets and metering rods) as compared to the older Performer 600 calibration, they appear to be much richer. It was after watching Matt explain fuel ratios and alcohols that my understanding came. Edelbrock is setting the factory calibration with oxygenated fuels in mind. Edelbrock tech recommended that when installing the AVS2 annular boosters in the primaries of my Performer 600, to start with the AVS2 factory calibration and tune from there.
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That’s why using Lambda is a better option than A/F ratio. It doesn’t care what fuel you are using.
 
Dale Davies said:
I can not remember all the details, but the engine would lay over like it was lean and the plugs confirmed. Jetting, drilling air bleeds or whatever they did had no effect due to the computer correction. Unplugging the fuel solenoid; I have no idea if it would go rich or lean. This was all in the articles documenting the build.
I would have had the articles if my ex weapon had not tossed a bunch of my books and magzines during separation.
My understanding of the Holley replacement was that it was like the Edelbrock Q Jet knockoffs, but it had the feedback feature built in like the original. If they had not modified crap out of the original Q Jet, it probably would have functioned with the shorter Engle cam. Remember that the early EFI systems all had PROM chips which had to be replaced with another with a tune burned on it. PROM; Programmable Read Only Memory. Later came the EEPROM chips; Electronically Eraseable .... These did not perform anywhere like the current flash programmable ECU's in use today.
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I'm might not be thinking correctly but here is how I see it.
For this example there is no reversion. Air (oxygen) and fuel are drawn into the cylinder as a rich mixture. Enough to cause a misfire. During this cycle what would be left over is unburned fuel and oxygen. Of the two the o2 sensor only detects oxygen. Oxygen in a higher proportion than if normal combustion had occurred. I think the o2 sensor will read that as lean.
In order for reversion to cause the o2 sensor to read this as a rich mixture it would have to selectively reverse only the unburned fuel past the o2 sensor and none of the unburned oxygen. Diluting the left over oxygen to the point of reading rich.
Again I'm not saying this is right.
 
92b said:
I'm might not be thinking correctly but here is how I see it.
For this example there is no reversion. Air (oxygen) and fuel are drawn into the cylinder as a rich mixture. Enough to cause a misfire. During this cycle what would be left over is unburned fuel and oxygen. Of the two the o2 sensor only detects oxygen. Oxygen in a higher proportion than if normal combustion had occurred. I think the o2 sensor will read that as lean.
In order for reversion to cause the o2 sensor to read this as a rich mixture it would have to selectively reverse only the unburned fuel past the o2 sensor and none of the unburned oxygen. Diluting the left over oxygen to the point of reading rich.
Again I'm not saying this is right.
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Rich in, rich out. A missfire pushes out the air molecules as well as the complex of HC molecules. The air is only composed of 21.9% O2 molecules which is displaced by the HCs, still reading rich.
Remember that liquids change phase when going to the gaseous state and increase in volumn tremendously during that phase change, displacing the air/nitrogen. This is how the mixture reads rich when air/fuel passes out the exhaust valve during the critical scavenge cycle if EVC is a bit late for the head flows available. To compensate the exhaust valves could be recessed or sunk into the head a bit, allowing the fresh charge to pass over the almost closed exhaust valve.
Water when changing phase from liquid to steam expands 1,600 times. This phase change requires huge amounts of heat taken from the air when using water injection in an ICE, which elps control detonation. The huge expansion also aids cylinder pressure.
 
Dale Davies said:
Rich in, rich out. A missfire pushes out the air molecules as well as the complex of HC molecules. The air is only composed of 21.9% O2 molecules which is displaced by the HCs, still reading rich.
Remember that liquids change phase when going to the gaseous state and increase in volumn tremendously during that phase change, displacing the air/nitrogen. This is how the mixture reads rich when air/fuel passes out the exhaust valve during the critical scavenge cycle if EVC is a bit late for the head flows available. To compensate the exhaust valves could be recessed or sunk into the head a bit, allowing the fresh charge to pass over the almost closed exhaust valve.
Water when changing phase from liquid to steam expands 1,600 times. This phase change requires huge amounts of heat taken from the air when using water injection in an ICE, which elps control detonation. The huge expansion also aids cylinder pressure.
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Im starting to change my thinking about EVO and EVC. Not so much as it relates to overlap but more in general terms how EVC and EVO are affected by rod to stroke ratio and the time that the piston spends around TDC and BDC.

To that end, a higher R/S ratio may want an earlier EVO so that when the piston reaches BDC you are at or near atmospheric pressure to reduce pumping losses. Since the piston is moving around BDC quicker (and I’m assuming faster) if you delay EVO you increase the pumping loss.

Which makes me assume (at least at this point) that when the cam is advanced and the power goes up that it is more likely due to the earlier EVO and reduced pumping losses (even though you may and probably do give up some of the expansion) and not so much to the earlier IVC.

And if that’s the case then a high(re) R/S ratio and a late EVO may be hurting power.

Ive always been of the opinion to delay EVO so that you get as much out of the expansion stroke as you can. But now I’m questioning that philosophy.

I also think that header sizing is impacted by this, as the sound/pressure waves would have to be different with different EVO’s.

The more I learn the more I learn I don’t know much.
 
Rat Bastid said:
Im starting to change my thinking about EVO and EVC. Not so much as it relates to overlap but more in general terms how EVC and EVO are affected by rod to stroke ratio and the time that the piston spends around TDC and BDC.

To that end, a higher R/S ratio may want an earlier EVO so that when the piston reaches BDC you are at or near atmospheric pressure to reduce pumping losses. Since the piston is moving around BDC quicker (and I’m assuming faster) if you delay EVO you increase the pumping loss.

Which makes me assume (at least at this point) that when the cam is advanced and the power goes up that it is more likely due to the earlier EVO and reduced pumping losses (even though you may and probably do give up some of the expansion) and not so much to the earlier IVC.

And if that’s the case then a high(re) R/S ratio and a late EVO may be hurting power.

Ive always been of the opinion to delay EVO so that you get as much out of the expansion stroke as you can. But now I’m questioning that philosophy.

I also think that header sizing is impacted by this, as the sound/pressure waves would have to be different with different EVO’s.

The more I learn the more I learn I don’t know much.
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A lot of things go on in a running engine and most are interacting with eachother. Change one factor and it can affect another.
Delay EVO does function to get as much energy from the expanding combustion gases. This likely comes at the expense of scavenging during overlap with the piston close to TDC. The entire package is to be considered and the best combination comes at the expense of a lot of dyno testing of combinations where minimal output changes can be noted.
 
And there you have it… 3 plus pages worth of a pissing contest chock full of more than enough misinformation to make you head hurt.
 
I’ll simply just add this for the benefit of the OP, as to not get dragged into the mess of much of what has been put out here so far. My advice would be to find a reliable A/F or dual band O2 sensor and gauge to install and do some research into the ACTUAL way O2 and A/F sensors REALLY work, to gain an understanding and then find someone locally who can help hands on who is familiar with turning with them. A/F gauge is not the be all end all of engine tuning but can give you a window into what is going on during a run or cruising etc.
 
The spark plug is the ultimate witness to the burn. Widebands read what the mixture is after it has left chamber and continued to burn in the exhaust pipe. Its funny when people claim unleaded fuels don't colour plugs but somehow manage to blacken exhaust pipes and the underside of air cleaner lids.
 
Lonewolf3165 said:
A/F gauge is not the be all end all of engine tuning but can give you a window into what is going on during a run or cruising etc.
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I agree with that.
All these methods of 'reading' have a learning curve and none are perfect.
It is why I asked the OP to post his goals for the AFR gage.

Gages and loggers are not neccessary for most tuning.
Tune for Best Performance.
Mattax said:
Finally, whatever you chose to do, Tune for Performance.
Wideband UEGO Air/Fuel Sensor
Click to expand...
 
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Lonewolf3165 said:
I’ll simply just add this for the benefit of the OP, as to not get dragged into the mess of much of what has been put out here so far. My advice would be to find a reliable A/F or dual band O2 sensor and gauge to install and do some research into the ACTUAL way O2 and A/F sensors REALLY work, to gain an understanding and then find someone locally who can help hands on who is familiar with turning with them. A/F gauge is not the be all end all of engine tuning but can give you a window into what is going on during a run or cruising etc.
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Sounds like you are in consensus with most on this thread.
 
Lonewolf3165 said:
My advice would be to find a reliable A/F or dual band O2 sensor and gauge to install
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That’s exactly what the op asked. He’s asking for experience with what afr gauges are inexpensive and reliable. To which you added nothing.
 
I bought an AEM gauge. It works pretty good. Good enough for the type of tuning that I do. (Street and occasional pass down the track) I have it rigged up temporarily with the long cable thru the vent window. I like being able to see how a metering rod change directly affects the afr. I’m about average when it comes to tuning carbs and it’s a handy tool to have. I feel like I have become more adept at tuning after adding this tool
 
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