I am getting desperate, my 95 WRX failed the MOT on emissions, and i need to get it re tested by the end of tomorrow. The CO is 10%!!!!!!

So far i have changed the Lambda sensor, the sirflow sensor and tried a different ECU, but so far it has not improved at all.

Has anyone got anymore ideas that i can try, i am running out of ideas, has anyone else had this problem with there Subaru.

Thanks very much.

 

There was a post on here a couple of weeks ago about "Friendly" MOT Stations?

Have a look on search.

Regards

Alan MaC

 

Has the car been decatted as if it has get the cat put back on for the MOT.

 

Jeees thats high!!!

Mine was 0.6 % and a new cat took it to 0.04%

What was the rest of the emission readings like hydrocarbons.

 

It is usually decatted but i have put both of the cats back on. I am thinking that is is not the cat as i don't think that it would make 10% of difference.

The figures from the test are;

CO Level 10.67%vol
HC Level 216ppm
CO2 Level 8.10%vol
O2 Level 0.37% vol
LAMBDA 0.73

I just can't think what else to try, could it be the engine coolant temp sensor. Could it be that the sensor is telling the ecu that its cold and its overfuelling for that reason?? Or am i clutching at straws.

Thanks

 

Obviously its overfuelling. Check out the fuel pressure regulator and the coolant temp sensor. I assume all the basics have been looked at (ignition side, air filter etc)?

 

Well, its passed the MOT now.....

The final diagnosis was, the Lambda was buggered, but it was only buggered because there was something wrong with the ECU. When on the gas analyser, the CO was low but then kept going sky high. When the ECU was changed the CO then went down to 0.38%-0.45%, So close but not quite there.

So then i changed the Centre cat for another one and went back on the machine with fingers crossed. This time the CO was 0.06%. At last the problem is cured, and it runs much better. I am just glad that the MOT Station was helpful and let me keep taking it back to check the Emissions, with no retest fee.

Thanks for all the helpful ideas anyway.

 

Hi mate if you can prove that your car was manufactured before September 95 it doesnt need to undergo the strict cat test for the mot. All scoobs that are pre-sept 95 are exempt because they don't exactly match the DOT register. My car was the same but I pointed out it was a 94 and they did the non-cat test for emmissions which is far easier to pass!