Lambda Signal Wire Help

[Matt-T]

Hi all, i own a Mk4 Golf unfortunately it is not the GTi, so hope you don't mind me posting.

What colour is the lambda signal wire?

Im guessing the two white ones are for heated element, which leaves me grey and black.
I need to tap into one to put an Air/Fuel Ratio gauge in.

Thanks in advance

[tshirt2k]

An air fuel gauge wont tell you much. Especially if its a narrow band sensor

[Matt-T]

Yeah i know,
Just gives me Lean, Rich, Optimal on a narrow band, where as a wide-band would be more accurate.

It was an impulse buy as i had a gauge holder for 3 gauges, and only had 2, so rather than buy and oil temp/pressure i just bought the A/F one.

[tshirt2k]

oil pressure would have been better. 

[Hoggy]

Im thinking that grey should be signal, about 90% sure

[danny_p]

i would advise against tapping into the signal wire from the lambda that the ecu is reading. 

the output from a narrow band sensor is very high inpedance or to put it another way the signal is very weack  adding something extra to system can distort the output from the sensor so the ecu ends up with an incorrect reading and ends up trimming the fuel incorrectly.

if you want the gadge even tho there next to useless as tshirt2k said.    fit another lambda for it idealy or just read the live data off the ecu before and after to make sure its not distorted the readings