o2 sensor help on my 91 golf

[steveo3002]

while messing with my 91 golf g60 a while back i noticed it was a fair bit faster and crisper with the o2 sensor unplugged

this made me assume the sensor was dud/worn out so i replaced it with a proper bosch jobbie(no i didnt get copper slip on it ) ...still the same , drives nicer with it undone

any ideas ..its like its giving out the wrong signal to dull the performance? or maybe i bought a dud one ?

[daverapid]

:)Go to a friendly MOT garage and get an emmisions test carried out.

[steveo3002]

doesnt really prove anything ...it passes the mot emmisions

[tctech]

i think you are looking in the wrong place the lamba sensor only reads gasses going past it and the ecu does the adjustments if disconnected the ecu will put in a nominal value for the sensor so it dosent melt a piston etc but the lambda is only a narrow band sensor on road cars1500rpm to 3000 rpm usually . if the car goes better as you say .its better to look at the coolant temp sensor values or air mass 1st .unless a sensor is faulty and going to ground or giving a very inaccurate reading not within the safe parameters of the ecu program it may not cause a fault code but will restrict the engines performance .hope this helps

[steveo3002]

^^ not really sure what you are suggesting

the way i understand the ecu has a basic map thats near enough , the o2 chimes in and fine tunes that map for supposedly perfect running

I'm sure it should be better with it all connected?

[retrowagen1234]

on the g40 forums theres a basic guide to tuning the 02 sensor ... you need to measure the ohms accross the pins (cant remember how many there are) and tweak the screw untill it reads as it should... i had to do it on my old g40 and it worked a treat...