I was looking at one of those Air/Fuel ratio gauge kits you can buy now. Does anyone know how theyre fitted? I always thought they where a sensor in the exhaust at some point and if thats the case i wont bother, dont fancy making any holes like.

Cheers

Some use the cars OEM Lambda sensor - if you car doesnt have one, then one will need fitting to the exhaust.

They are only as accurate as the sensor, and if they use the OEM sensor - thats not very accurate....

The expensive ones use a wideband lambda - these are accurate enough to tune with, but the price difference is huge...

One using a wideband lambda is £200+, one using a std lamdba £30ish.

TBH Id only use one if you planning on using it to tune the car, in which case spend out on a good one, if your checking for problems, compromise and get an EGT gauge instead at £80-£100

Yeah, basic ones don't really tell you anything. If you know you've got bad fuelling, it's not going to tell you much!

I think the cheap one gets you a probe as well, I have one in my garage, I will get a pic.

I dug these out:

The Air/Fuel gauge has four wires (going to the ECU) and an exhaust probe!



The one on the right is a 'lean' gauge, which goes red/green depending on the fuelling (for turbo engines).