182 Failed MOT due to HC

[Carbon-Rain]

My 182 just failed the mot due to high HCs, it has a after market air intake and a ktec exhaust system the ecu is running a rs tuner 98 Ron map.

What do I need to do to get it through the emissions test?

 

[Fred@BTM]

new lambda probably

 

[Carbon-Rain]

new lambda probably

I recently replaced the Pre Cat Lambda, I must admit it was a bit of a sod to do so there is always the chance that I made a hash of it. Time to get the Garage to check it then. I can feel some expense coming on now.

 

[Fred@BTM]

oh, in that case then no idea, maybe a new set of plugs might help it, OR the thermostat is goosed (can cause over fueling)

 

[leesclio]

Re hc mot fail

Hi with regard your mot failure. I don't think its the lambda sensor as this measure s oxygen and would have failed the test on this as well. Hc is hydrocarbon which is generally unburnt fuel. This is generally because of an inefficient catalyst ie the mot tester is not getting it hot enough. My advice as an mot tester would be to give her a proper drive get her nice and hot then retest. Also try adding a good quality fuel additive. Hope this helps.

 

[KevF182]

Re: Re hc mot fail

Would be good to have the three types of gas measurement posted up (Lambda, HC and CO) to get a better idea of what going on, and if its only failing on idle, fast idle or both. If Lambda is OK it could still relate to incomplete combustion, which could be poor quality ignition/slight missfire. have you had a flashing dash light recently?

The Catalyst's primary function is to reduce the CO content, not HC.

 

[plymcl172]

Would say take it to another mot place but would be naughty to drive it after a fail.....

 

[ben lee]

if the cat wasnt up to temp then co reading would be out too.
if the tester did the mot test correctly after doing a BET test and failing he would have to do a full cat test and 95% the time the car will be up to temp by the time he gets to the 2nd fast idle test.

was it only the hc high?
hc means its not burning the fuel i would try changing the plugs/leads or poss the rstuner map is wrong if you still have your original map i would put it back on for your retest..

 

[Dan@SJM]

Could also be an air leak...

 

[Carbon-Rain]

The guy at the garage thinks it could be the cat that is the problem, I am not sure if it's an original cat or an aftermarket one.

Where the best place to get another cat from?

 

[bmh.01]

Re: Re hc mot fail

Hi with regard your mot failure. I don't think its the lambda sensor as this measure s oxygen and would have failed the test on this as well. Hc is hydrocarbon which is generally unburnt fuel. This is generally because of an inefficient catalyst ie the mot tester is not getting it hot enough. My advice as an mot tester would be to give her a proper drive get her nice and hot then retest. Also try adding a good quality fuel additive. Hope this helps.

Yes it measures oxygen content in the exhaust to determine combustion completeness and the adjust fuelling to suit. Unless he's done something daft like starting it from cold and testing it should be ok.

 

[bmh.01]

The guy at the garage thinks it could be the cat that is the problem, I am not sure if it's an original cat or an aftermarket one.

Where the best place to get another cat from?

Do you do a lot of short trips?

 

[ben lee]

if it passed the co. part of test the cat will be fine.

 

[Carbon-Rain]

Do you do a lot of short trips?

The trip to work is only 7 miles.

I have noticed that the mpg has dropped from 32 to 27 over the last week too.

 

[lighty]

What was the out come on this?

 

[Carbon-Rain]

It turns out the cat was not getting warm enough as I have a sports cat. So a drive of a few miles at 50-60 warmed it up enough and when tested again the car passed.