G60 Co-Pot and exhaust gas hydro carbons

[P3rks 11]

I've been trying to set up my car since the headgasket was replaced and I'm struggling with the Co-Pot. I know it's meant to be between 500-600 ohms on idle across the two outer pins.

 

Can someone clarify this? Is it with the blue temp plugged in or unplugged? Also what setting on my multimeter do I use? I have 200, 2000, 20k, 200k and 2000k.

 

Anyway I was struggling to get it accurately between 500-600 ohms. So I took it to a local garage who put it on the gas tester.

 

CO2 was 0.5% and hydro carbons was 30. The MOT guy said it's running cleaner than a new car and suspected it running lean.

 

No amount of screwing of the Co-Pot made a difference on the screen. Until I unplugged the blue temp and tried. I got the CO2 at 1.5% plugged the blue temp back in and it dropped to 0.5% again.

 

Any ideas what's going on?

[steveo29 0]

for what its worth i found the procedure somewhere...i think its blue sender off and rev 3x times , anyway i played around with it and the meter didnt change at all

 

if yours is about right which it sounds like it is , set the pot to 450 or whatver they reccomend with the engine off and leave it

[andycowuk 0]

blue temp sender, lambda probe and co pot all adjust whats going on as conditions change; blue temp send for enging temp, CO pot for air intake changes and O2 probe gives feedback on how its all working. (Wide and closed throttle switches, MAP sensor in ecu, knock sensor etc all add to this mix too)

 

lambda probe controls the co2 etc when your not asking for power and CO pot is reletively redundant, so i'd expect not to see much in the above scenario. Once you ask for power, the lambda gets ignored and it chucks petrol in reletive (in part) to the CO pot position; so the right mix or A/F could be at 450 ohms or could be at 650 - you cant tell unless you have a wideband sensor on there; best you can do is listen for pinking, make it richer to see if that stops it otherwise wind the advance back a bit and lean it off again to see what its like.

 

You'll need to set the co pot to the correct resisitance with the engine off and the co pot disconnected. if the resistance doesnt move with the screw, it may be shot. You set your multimeter based on the maximum reading you expect; expect more than 200, and less than 2000 so its the 2000 setting you want.

Edited August 5, 2011 by andycowuk