please recomend the best Air/fuel ratio meter for the money.

[christopher@cam]

Thank you for the help.

[DRACO A5OG]

Lm1

[ChkbookMechanic]

It really depends on what you want to do. Do you want one that mounts in your cabin or do you want a handheld one? Personally, I like ones that mount inside the car as opposed to ones that are handheld.

The ones offered by PP seem to be good quality (but I can't say since I haven't used them).

[KobaltBlau]

I would go with something from Innovate Motorsports. Their site shows their entire line, and they have both "portable" stuff and permanent mount. For a "portable" I there is a new LM-2 that succeeds the LM-1 which means deals on the LM-1 if it has eveything you want, or new features with the LM-2. I think the LM-2 looks pretty neat.

[beepbeep]

LM1 + auxBox for serious work and LM2 + display for permanent installation just displaying AFR in the car.

[KobaltBlau]

Originally Posted by beepbeep

LM1 + auxBox for serious work and LM2 + display for permanent installation just displaying AFR in the car.

Do you mean:

LM1 + auxBox for serious work and LC-1 + display for permanent installation just displaying AFR in the car.

As I understand the brand new LM-2 replaces the old LM-1 + auxbox deal with some extra features on top of that. The LC-1 is the inline controller that is perfect for permanent installation with one of innovate's gauges.

[fireant911]

Westach... without question. This device has been great. Although the 'other' unit is apparently much more popular, I have never understood the attraction.

[84 911 WideBody]

Originally Posted by KobaltBlau

I would go with something from Innovate Motorsports. Their site shows their entire line, and they have both "portable" stuff and permanent mount. For a "portable" I there is a new LM-2 that succeeds the LM-1 which means deals on the LM-1 if it has eveything you want, or new features with the LM-2. I think the LM-2 looks pretty neat.

+1 here use them work very well.

[mamut]

NGK AFX's.

[christopher@cam]

thanks all for the feedback.

[911pcars]

Stay away from narrow band-type A/F meters. Not accurate except for around 14.7:1

Sherwood

[fireant911]

Originally Posted by 911pcars

Stay away from narrow band-type A/F meters. Not accurate except for around 14.7:1

Sherwood

Sherwood,
This is where I cannot understand the attraction for the LM units... hopefully you can elaborate on this point. Using my car as the basis and assuming that the Lambda system (81 SC) is both hooked up and functioning properly, the Westach gauge, for example, is simply providing a visual display of the electrical signals produced by the O2 sensor. I am assuming that the same input is going to the Lambda unit itself. I realize that the Lambda unit makes several 'corrections' to the A/F ratio per second yet what advantage would having a unit that is purportedly able to display more accurate readings of the A/F ratio if it is measuring a system that operates under the principle of shooting the A/F high and then low to acheive an average A/F ratio of 14.7:1. Would this not be equated to using a micrometer to precisely measure the length of a piece of wood when this wood was cut using a standard tape measure? An explanation of the advantage of a wide-band versus a narrow band would be very much appreciated.

[berettafan]

unless you have doodads on all 6 outlets you are getting an average anyways.

not to mention if your car isn't sending the exact same a/f mixture to each cylinder (webers for example) then you could conceivably have 4 cylinders perfect, 1 way rich and 1 way lean (on the same side) and never find out.

[jonbot]

I like the PLX gauge, easy to install, and expandable to display things like fluid temp, fluid pressure, vacuum/boost, all on one OLED gauge. You can customize gauge faces as well. I also like the installation, everything is sent over 1 serial cable, so all you have to do is run a coax wire up to the front of the car, and you can still expand with more modules in the rear of the car whenever you want. The weak point is the data logging, but as a standalone gauge I love it.

[911pcars]

"This is where I cannot understand the attraction for the LM units... "

O2 Sensors provide feedback to the ECU as to the actual A/F ratio produced by the fuel system. In a factory stock system whose goal is to produce an ideal 14.7:1 for minimum emissions, a sensor having more sensitivity in that mixture region is quite satisfactory.

However, that target A/F ratio is not the mixture required for maximum power. That's where a wide band sensor (often referred to as an A/F sensor) can more accurately measure fuel mixtures on either side of stoichiometric (14.7:1). Too rich or too lean compromises either power or engine longevity, and when the fuel system of choice can be adjusted accordingly or has less accurate fuel metering (i.e. carbs), then a fuel mixture monitoring system using a wide band sensor can be a most helpful tuning tool.

Sherwood

[fireant911]

Therefore, if one is still using the Lambda system, as in my case, there is no additional benefit to using a more accurate system such as the LM series?... The LM meters can not only register the readings in real time it can concurrently log that information though it cannot control the mixture?... Are these two statements correct? I realize that maximum power is slightly to the right of stiochometric but in the CIS systems what can be changed assuming that the Lambda computer is controlling the mixture? Are the LM systems only for the carbureted cars (this would make perfect sense)? Please bear with me here - I am only trying to understand why the wide-band systems are superior.

[MatthewBrum]

I would say the goal of the wide band sensor is to monitor your a/f ratio under all operating conditions and rpovide feedback. Narrow band injection systems are only in feedback mode under steady state part throttle conditions. A wide band injection system will provide feedback under full & part throttle ensuring max performance and economy. The ecu in your SC does richen the mixture under full throttle but does not provide feedback while doing so.

The biggest disadvantage to narrow band sensors is that they only tell you on stoichiometric, rich, or lean.

[KobaltBlau]

Basically a narrowband sensor's output looks like a step function, one side of stoich is very close to 0 volts and the other side is very close to max voltage. the transition is designed to be very sharp around stoich. This makes it easy for an ECU to treat the input as binary, either "too rich" or "too lean". Most production ECUs do exactly this at cruise, and just ping pong the mixture right around stoich. Typically these ECUs ignore the O2 sensor under WOT and go off of other sensors and a preprogrammed map. It is very difficult to measure an AFR much different than stoich with a typical narrow band 02 sensor, and you want richer at WOT, so the narrow band input is not useful to an ECU at WOT.

With a wideband sensor, on the other hand, the response curve is much closer to linear, so you will have a proportionately different output at 12:1 versus 14.7:1, so you can effectively measure 12:1. This comes in handy, if, for example, you have a tuned turbo engine and you want to know you're getting 12 or 13:1 at WOT for power and engine protection, and not 14.5:1. You wouldn't be able to tell this with a narrow band sensor. In fact, a good ECU could use the wideband input under WOT to target you right around a programmed value, instead of ignoring the 02 sensor in conditions other than cruise.

But to answer your question, if your ECU is designed to use a Narrowband sensor a wideband add-on is usually only useful for tuning and diagnostics, and not for hooking up to your ECU. However, there was a guy named klaus (username klatinn) on here a couple of years ago who was using the narrowband simulator output of his lm-1 (intended so you can replace your O2 sensor with a wideband sensor and still have a narrowband output to feed to your ECU) with some tricks so he could customize the AFR under WOT. This is an advanced trick with CIS, but very interesting! I have considered doing it but I now have an early SC without the lambda so it would require more work. More info on CIS hacking:

LM-1 WOT closed loop trick with freq. valve CIS

[KobaltBlau]

forgot to mention that said klaus is also the creator of the lm-1.