High Lambda reading,182 Exhaust.

[gilmour182]

HI,

Just like to see if anyone out there has any views on this.
My 182 just failed MOT for high "Lambda Reading" = too much Oxygen in my exhaust.
CO and HC passed by miles. Car is standard.
Going to have a good look for leaks in the exhaust.

Is there any chance that the twin tail pipe Exhaust "Blueflame"could cause this failure?
Seen on a ford forum of someone who had the same problem that was cured by covering up part of his big bore tail pipe.

Its getting a new upstream Lambda as soon as it arrives from northwest. Has had previous intermittant Upstream Lambda sensor circuit fault logged, but been clear for a while.
After looking in to it discovered the MOT lambda reading is not a true check on the sensor.

Any Ideas or Opinions?

Thanks.

 

[Grancio28]

hi mate ive come across this quite a few problems like this on mot failures, 9/10 its an air leak in the exhaust the lambda sensor can affect it but normally the c.o reading too. if there was a fault code stored for the lambda sensor dont assume its at fault without testing it, and that sometimes a fault code can be a symptom of another fault. alot of aftermarket exhausts have air leaks that can be repaired easily! i have heard of blanking off a tail pipe but it doesnt do alot! good luck.

 

[sideways danny]

block one of the tailpipes with a wet cloth. Perfectly legitimate, as you're just allowing the sensor to see un disturbed gases. Large tailpipes allow air to be sucked in from outside which gives a false reading

 

[gilmour182]

Thanks for the advice guys, working 12hr nights just now so hope to get a chance to have a proper look soon.
I didnt mention the HC value was Zero :-? Whats that all about?
And the exhaust system had a load of oil down it when the last engine chucked a rod.

 

[gilmour182]

Put a new upstream lambda sensor on and fixed the little blows at exhaust joints.
3 mpg better at 70mph and now passed with lambda reading = 1.003.
The exhaust would probably have sorted it out but , passed so happy days.