wideband lambda sensor options

[kwklein]

I've always used a bosch lsu 4.9 sensor but just realized that I'm limited to a maximum rich mixture reading of 0.65
This is for a racing application and I don't plan to tune this rich but if for some unknown reason my fuel does run richer than this setting I'll have no idea how rich the mixture may have gotten.

I've looked high and low and haven't been able to find a sensor that will indicate a mixture lower than 0.65

Can anyone point me in the right direction? Is it possible to tweek the resistance in the sensor to capture a richer mixer? I don't need to be any where near a value above 1.0 so I don't mind loosing capabilites on the lean side.

 

[mattsooty]

Why would you want to measure that rich anyway?

MS

 

[MacGyverS2000]

'twas thinkin' the same thing... above a certain point, who cares how rich you are, you just need to know it's time to cut waaaaay back on fuel.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[kwklein]

I understand what you guys are saying. I feel the sme way. Below 0.65 is excessively fat/rich. If I don't know roughly how fat it is then I'm guessing at how much to trim from the fuel. Granted I wouldn't trim out a huge amount and end up lean right away, but I also don't want to keep guessing at home much needs to be trimmed until I finaly start getting an accurate reading.

I guess I was just a little surprised that the sensors can't produce a reading below that point. One answer I got was since their meant for OE apps that they never needd to be designed for a lower reading.

 

[MacGyverS2000]

If you're so far into that rich region that you don't know how far, some more map tweaking needs to be done. Even if you do go into it, you should be able to figure out roughly how far and be able to back off a certain amount to put you back within measurement range (where you can then tweak appropriately).

Dan - Owner

http://www.Hi-TecDesigns.com

 

[mattsooty]

When you are talking about lambda values as low as this you have, I assume, moved far away from performance enrichment and well into component protection fuelling.

In which case you are controlling lambda for temp control which then becomes your feedback loop (and the lambda value, per se, become irrelevant. All of which has to be taken with a pretty hefty boundary condition of rich misfire.

MS

 

[JonathanK]

My NGK AFX reads 9-16:1 AFR (gasoline). Honestly, if its leaner than 16:1 or richer than 9:1 I don't care, because its way too rich. The more you need to read, the less resolution you will have. Remember, you have a 5 volt scale with probably an 8 bit or 10 bit ADC to work with. If you wanted to read from 6 - 25:1 AFR then you'd have very poor resolution as a whole unless of course your controller had a non linear output which would be terrible.