gtxdude
Well-Known Member
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?
A/F/R gauge for tuning
- Thread starter gtxdude
- Start date
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AEM I like it to get me in the ball park. Being that my engines can vary from stock-ish to pretty modified, each engine likes a little something different. Once you get a base line in on what’s said to be the perfect A/F for driving and W.O.T., you can adjust it quick and easy for best results on mileage and/or strip E.T.
I tried the Inovative dual 02, junk! Just junk. Waste of money.
I tried the Inovative dual 02, junk! Just junk. Waste of money.
I have the Innovative Dual 02 setup on my bench awaiting installation. Specifically, what issues did you have with yours?
dave ellis
Well-Known Member
My deadhead be sure to get one with a wideband sensor or you may be wasting your time or you may be wasting your time
I use an old Innovate LM1 to tune my carb. I think I paid $250 many years ago so not cheap. I weld an O2 bung into the pipe near the header and run the cable out through the passenger window 
. Its a temporary install.
. Its a temporary install.
MidnightSwinger
Well-Known Member
I have always had good success with this AEM.
AEM Electronics 30-4110 AEM Electronics Wideband Air/Fuel UEGO Gauge Kits | Summit Racing
AEM Electronics 30-4110 AEM Electronics Wideband Air/Fuel UEGO Gauge Kits | Summit Racing
gtxdude
Well-Known Member
I use an old Innovate LM1 to tune my carb. I think I paid $250 many years ago so not cheap. I weld an O2 bung into the pipe near the header and run the cable out through the passenger window
Have a 02 bung already from earlier. Don't want a permanent one in car just for test and tune then throw it in the drawer till next time.
Is the cable long enough to run from under the car through window?
MidnightSwinger
Well-Known Member
It’s 8 ft long
dave ellis
Well-Known Member
Spell check! Sheesh!
Gasoline Air/Fuel Meter (Dual Sensor)
Used it to tune every car I have, especially the dual carb dart 225.
Used it to tune every car I have, especially the dual carb dart 225.
Rat Bastid
Dunamis Metron
An O2 sensor is really a combustion efficiency meter. It can lie to you. And it will if you let it.
When the O2 sensor and the plugs agree the you can tune from there. When they don’t agree the plugs are right and as a tuner you have to figure out why the O2 sensor is saying what it is saying.
When the O2 sensor and the plugs agree the you can tune from there. When they don’t agree the plugs are right and as a tuner you have to figure out why the O2 sensor is saying what it is saying.
Cuda416
Well-Known Member
What would a person look for should this happen? I do see this as a way to get things "close" before a pull or running down a track for plug reading. Your input is appreciated.
ir3333
Well-Known Member
i've had mine so long i forget who made it but i just keep transferring it to each new build.
An excellent tool for tuning with no guesswork!
An excellent tool for tuning with no guesswork!
MidnightSwinger
Well-Known Member
Bad sensor, is the most common reason in my experience. You can also have issues with EGT(exhaust gas temp) messing with your O2 readings.
I have an AEM mounted in my van, along with a vacuum gauge. Immensely helpful being able to monitor what is going on at every throttle position, especially if there is some sort of circuit issue, transitions etc. Allows you to zero in on things rapidly. I never was good at checking plugs which I attribute to laziness.
I can rely on those two gauges along with feel, listening, seat of the pants and have gotten pretty good at dialing what I have in. It’s quicker than pulling the doghouse and checking plugs in my case that’s for sure. And then at the track I just use MPH as the other gauge.
I can rely on those two gauges along with feel, listening, seat of the pants and have gotten pretty good at dialing what I have in. It’s quicker than pulling the doghouse and checking plugs in my case that’s for sure. And then at the track I just use MPH as the other gauge.
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Rat Bastid
Dunamis Metron
What happens when you get a lean miss????? What do you think the O2 sensor will say?
That’s one quick example of how an O2 sensor can lie to you. It’s a dumb tool. It can’t think. You have to think for it and not take everything it says as gospel.
Also, you can run into reversion issues which will make the O2 sensor tell you fibs.
I think It will read lean if you have a lean misfire. The 02 sensor measures the oxygen left over from combustion. In the case of a lean misfire there will be more unburned oxygen left over due to incomplete combustion caused by a lean mixture.
Cuda416
Well-Known Member
Thanks, I completely agree it's a "dumb" tool, but still a tool and like every tool, it's use needs to be understood. I still think it's a decent way to get a ballpark but it's not a crutch either.
Cuda416
Well-Known Member
To this point, I watched a guy diagnose a rough idle one a newer car using some fancy gizmo. Easy to see in the wrong hands it would be a disaster but this guy understood how the O2 sensor worked and the tool had was able to tell him the duty cycle of the sensor. Turned out to be just on the fair edge of tolerance from age. As I recall, all the signs pointed to something else (don't remember what) but knowing the tool AND the proper operation/operating characteristics was key.
So again, to your point, a person still needs to know some stuff and not rely on the tool to tell them what's wrong. It's an indicator in a pile of other indicators.
Dave999
Well-Known Member
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
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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Can you explain this. If the charge is unburned then more oxygen is present in the exhaust. The sensor reads the presence of oxygen not unburned hydrocarbons. An HC meter could do that if you had a 4 gas analyzer hooked up.
When I see lean misfire on the dyno my o2 sensors show lean.
AFR meters are great for tuning but as with many diagnostic tools you have to know what to do with the information. Does the AFR reading line up with the drivability issue, exhaust smell, plug condition, etc?
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