O2 Sensor

[Pilot25dmc]

Right, where to begin???

You will all remember the small fire I had in the engine bay a few weeks back that melted the wiring of the o2 sensor, well since then my car has been hunting like crazy, and I mean REALY bad, I had totaly forgotten about the o2 sensor and thought that it was just down to the cold weater but tonight I decided to test my mixture as the car seemed really really rich. I had only passed my MOT about 4 days before the fire and the car was sitting at 3% and it idled and drove perfectly, since the fire which must have damaged the o2 sensor the car has felt lumpy, the engine was noisy and had a really bad hunt and the whole car shook. I take it that if the o2 sensor is damaged or not working the car computer auto adjusts the mixture to make the car richer??

I decided to adjust the mixture to see if I could solve the hunting and I had to lean the car back atleast half a turn of the screw untill the hunting stopped and the car idled perfectly. I have let the car cool down and from cold it starts first turn of the key and the idle is smooth with no hunting, all I want to know is should I fit a new o2 sensor? I have the stainless exhaust and no cat and isnt the whole purpose of the o2 sensor to monitor the cat?

I have ordered a new one to be on the safe side but since the car seems to be ok I am not sure if I want the hastle of adjusting the mixture again for the 6th time this year.

[Glen & Sam]

hi alister

best one for this would be nick t or Rich matey if ant got a flux in it i,m no good

[stunned_monkey]

Al, your mixture is running too high if it's at 3% with lambda working. The lambda system will be leaning it off as much as possible to get it down to 1% but it only has a "window" af adjustment of a certain size.

With a failed lambda sensor (the ECU "sees" an open circuit), it defaults to a fixed duty which under normal circumstances, would be "slightly rich".

A lambda sensor/system is required if the exhaust has a cat. The metering system is designed to use it and won't work properly without it, even if you have no cat.

[NickT]

You can use a universal Zirconia 0-1.0v 18mm Spark plug thread lambda sensor like:

http://www.gendan.co.uk/product_O21WIRE.html

This single wire connects to the blue cable to the fuel computer (behind passenger seat in your RHD car)

If you disconnect the oxygen sensor electrically via the blade connector that is behind the rear near side tyre then the fuel computer will default to 50% duty cycle and you should hear the bleed off (frequency) valve buzz. This is located on the right hand cylinder head cover near the coil cover.

The emissions should now drop to between 1 to 1.5%.

If you need any help give me a ring.

Hope this helps.

NickT

[Rottbott]

Glen & Sam Wrote:hi alister

best one for this would be nick t or Rich matey if ant got a flux in it i,m no good

Why post then?