Air/Fuel Ratio Gauge - Should I have one?

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Rory
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Air/Fuel Ratio Gauge - Should I have one?

Post by Rory »

Im running 15 PSI on my standard Rev 2 tubby. A bloke at my work told me I should also have a Air/Fuel ration gauge. Is this correct?? He was talking about me letting my car run lean etc etc. Obviously I dont want this to happen. How good are the guages? Are they really accurate enogh to let me know if my engine is in danger?

Thanks

Rory
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Re: Air/Fuel Ratio Gauge - Should I have one?

Post by Driftlimits Performance »

He Rory mate

My air/fuel ratio gauge has made no difference to how I drive. They're flashy lights and thats about it! Unless you fork out £300+ for a wideband 02 sensor.

I've got an autometer A/F meter. And I love it! The ecu is constantly changing the ratio, and I mean constantly, it flickers around loads! But, when your foot is flat on the floor, it runs constantly rich. If for instance I stamped my foot down and it ran constantly lean, I'd stop! But the ecu takes great control over the fueling, so monitoring it doesn't do much.

Although, I use it to judge when to start driving the car. ie In the mornings I leave the car running to warm up. But after work, the car is cold. Get in, start up and the A/F reads lean. This slowly goes round to rich whilst it finds the idle, at which point I drive off.

I think a wideband O2 sensor is essential on a highly modded tubby, one with a piggy back/standalone ecu where you adjust the fueling, but stock, no need really. Although If I were you I'd get one, they look so cool!

Get one 8)

HTH
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Re: Air/Fuel Ratio Gauge - Should I have one?

Post by stevecordiner »

You can buy a wideband O2 gauge with sensor these days for around 150 quid. However your car wont be running lean, these cars run pig rich as standard, especially rev 1/2's

A narrow band A/F gauge is useless for anything other than in car bling.
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Re: Air/Fuel Ratio Gauge - Should I have one?

Post by Driftlimits Performance »

Hey Steve

Where can you get a wideband for £150?
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Re: Air/Fuel Ratio Gauge - Should I have one?

Post by JJ »

A narrow band A/F gauge is useless for anything other than in car bling.


Snob ! :wink:

The narrow band o2 probe is a lazy sensor to start off with and doesn't compare with the widebands. Basically the refresh rate is important for tuning.

Apexi do a turbo timer / o2 sensor combo which has a digital a/f ratio readout... you can see fluctuations in the a/f values, but not to be comared with a wideband still !

Still give you a good idea when on load if it goes lean or not.

If your cars stock, then you shouldnt worry about it, even if you've increased the boost. Only when you've change the turbo out for a monster thing and trying to push 20 psi + through the engine when you'd need to consider one !

:)
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Re: Air/Fuel Ratio Gauge - Should I have one?

Post by jonno »

I am currently deciding which gages to use - where can i get a wideband O2 and AFR meter for £150?
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Rory
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Re: Air/Fuel Ratio Gauge - Should I have one?

Post by Rory »

Thanks guys. Looks like I dont have to worry about it then.

Rory
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Re: Air/Fuel Ratio Gauge - Should I have one?

Post by stevecordiner »

Skywalker wrote:Hey Steve

Where can you get a wideband for £150?


I've got an M300 one of these :) $300 is about 150 quid with the current 3rd world dollar values lol

http://www.plxdevices.com/onlinestore_international.htm

It doesnt datalog, but is dead easy to fit if you have a wideband bung on your dp. PLus you get a nice digi LED readout
Last edited by stevecordiner on Tue Dec 21, 2004 3:47 pm, edited 1 time in total.
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Re: Air/Fuel Ratio Gauge - Should I have one?

Post by JJ »

jonno wrote:I am currently deciding which gages to use - where can i get a wideband O2 and AFR meter for £150?


I'm a fan of the AEM type and will probably settle for one of these :

Image

These have a sweeping display and a digital output... works out around £250 circa.
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Re: Air/Fuel Ratio Gauge - Should I have one?

Post by MR2Mania »

Guys, an AFR meter is USELESS unless it's got a wideband giving it the reading. It's not just the refresh rate, as JJ suggests, but the way that it creates it's scale. A narrow band only looks at a "narrow band", ie only the area around 1.0lambda (ie part throttle and idle). It won't read the ratios that you need when on power.

Also, the narrow band oscillates from (I *think*) 0.2v to 0.9v for the same of achieving 1.0 lambda at idle and cruise. A wideband device normally allows you to set the scale for volts versus lambda according to the device that will be displaying the readings, but generally the sensor is 0-5v, and 0-5 lambda.
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Re: Air/Fuel Ratio Gauge - Should I have one?

Post by MR2Mania »

stevecordiner wrote:
Skywalker wrote:Hey Steve

Where can you get a wideband for £150?


I've got an M300 one of these :) $300 is about 150 quid with the current 3rd world dollar values lol


And then there's shipping, duty and VAT on top! ;)
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Re: Air/Fuel Ratio Gauge - Should I have one?

Post by Driftlimits Performance »

Guys, an AFR meter is USELESS


Unless you want one :? In which case its not!
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Re: Air/Fuel Ratio Gauge - Should I have one?

Post by MR2Mania »

Skywalker wrote:
Guys, an AFR meter is USELESS


Unless you want one :? In which case its not!


Sure, it might *look* nice, but it's USELESS! Trust me! ;)
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Re: Air/Fuel Ratio Gauge - Should I have one?

Post by stevecordiner »

MR2Mania wrote:

And then there's shipping, duty and VAT on top! ;)


The shipping of 17 quid is a real painful one and IIRC I had to pay about £25 duties and VAT.

So thats up around £200 for the basic and around 330 for one that interfaces with a laptop and datalogs. Still compared to the price of a motec lamda meter (850 + VAT + delivery from fennies ... PMSL) its a bargain :)

Actually it was ideal for me, because the plx one has 2 outputs, wideband and narrow band. In theory I can feed the narrow band output back to my power fc and feed the wideband output to my datalogit. That way I am getting the O2 signal to the power FC was a wideband reading whilst also being able to datalog my air fuel ratios. That seems a good deal to me for the price
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Re: Air/Fuel Ratio Gauge - Should I have one?

Post by MR2Mania »

stevecordiner wrote:
MR2Mania wrote:

And then there's shipping, duty and VAT on top! ;)


The shipping of 17 quid is a real painful one and IIRC I had to pay about £25 duties and VAT.

So thats up around £200 for the basic and around 330 for one that interfaces with a laptop and datalogs. Still compared to the price of a motec lamda meter (850 + VAT + delivery from fennies ... PMSL) its a bargain :)


I bought myself an Innovate Motorsports LM1 (http://www.innovatemotorsports.com/products/lm1.php). They also do a "gauge and sensor" kit. I bought it in the UK though, and organised a GB - we got it for £245 with all taxes paid for.

I'm semi-permanently installed it in my car, but I could take it out and put it into another person's car.

It works VERY well, but it's not as good as the MoTeC one, or other more expensive items. You get what you pay for...
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Re: Air/Fuel Ratio Gauge - Should I have one?

Post by jonno »

MR2Mania wrote:Guys, an AFR meter is USELESS unless it's got a wideband giving it the reading. It's not just the refresh rate, as JJ suggests, but the way that it creates it's scale. A narrow band only looks at a "narrow band", ie only the area around 1.0lambda (ie part throttle and idle). It won't read the ratios that you need when on power.

Also, the narrow band oscillates from (I *think*) 0.2v to 0.9v for the same of achieving 1.0 lambda at idle and cruise. A wideband device normally allows you to set the scale for volts versus lambda according to the device that will be displaying the readings, but generally the sensor is 0-5v, and 0-5 lambda.


So what should i get mate? Bear in mind I dont really envisage doing much fuel mapping myself and I just want to spot a potential problem while on track etc and be able to back off and avoid any damage?

Neil.
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Re: Air/Fuel Ratio Gauge - Should I have one?

Post by stevecordiner »

I've seen one of those before, has in built datalogging doesnt it? Always looked a nice bit of kit :)
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Re: Air/Fuel Ratio Gauge - Should I have one?

Post by jonno »

http://www.rpmoutlet.com/aemgauge.htm

Is that good enough for my needs?
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Re: Air/Fuel Ratio Gauge - Should I have one?

Post by stevecordiner »

If I were you I'd try and get a cheap wideband gauge - something like the basic plx. Datalogs would be more for tuning purposes. But a gauge could be handy to highlight if say your fuel pressure dropped for some unknown reason when you when boosting.

Depends what you want to use it for, I mainly got mine as I was playing around with fitting my power fc - had I plugged it in as it was when I first recieved it I would've destoyed my engine, the wideband showed me the map on the FC was for much larger injectors.
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Re: Air/Fuel Ratio Gauge - Should I have one?

Post by MR2Mania »

stevecordiner wrote:I've seen one of those before, has in built datalogging doesnt it? Always looked a nice bit of kit :)


Yeah, it's pretty cool! I was put off buying it by a tuner, but then he admitted that I wouldn't get a professional wideband kit without spending a fair bit more money.

I don't use the LM1's internal datalogging, because I've got full datalogging in my MoTeC M800. I simply had to program the LM1 to output in the scale that my MoTeC wanted. It wasn't as simple as that though, as there seems to be a slight voltage shift, so I basically had to work out what that offset was, and build it into my formula for the output. Works damn well now, in the MoTeC it's within 0.01lambda of what the LM1 displays.
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