MOT Fail on high emissions


Speed_Freak

Speed_Freak

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Feb 8, 2012
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I'm trying to solve a Puzzle why my Ej8 coupé failed on emissions. But I have fitted a new Denso manifold Oxygen sensor and new spark plugs and put some CataClean in the fuel tank.

Also to note the car has been sitting since march but I try and get the engine up to temperature twice a month. Only thing with out getting a code reader I suspect it could be is the Air Temp sensor which looked like it was warn around the rubber. Any insight that fix the issue would be great.
Also to note Lambda reading was at 1.066, HC 70 and CO 0.30
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Considering its been sat for 4 months, the first thing I would do is go on the motorway and sit around 4000 rpm for about 20 mins and then get a retest. Do that before you start spending money on parts you may not need.
 
Ryan-EK9 said:
Considering its been sat for 4 months, the first thing I would do is go on the motorway and sit around 4000 rpm for about 20 mins and then get a retest. Do that before you start spending money on parts you may not need.
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True it's worth trying a motorway run. And someone I know also suggested giving the engine a oil change is that worth trying too? I thinks it's been a while since the last owner did an oil change.
 
I wouldn't say it's necessary but it also won't do any harm doing an oil change. Your call really.
 
Also one thing I will mention as I'm not sure if it's applicable or not? I had an advisory on the MOT test quote "Rear Exhaust has minor leak of exhaust gases". Could this effect the results of emissions test?
 
Yes and no. If the leak is behind the lamba sensor then it won't affect the readings, but it does if it's the other way round.
 
i dont think its anything to do with the IAT

did you properly heat up the cat before you went into the MOT centre?
 
I had the same thing with my impreza (i no its not a honda) once even tho it was run for 20 mins the cat still was not hot enough to start working correctly, i had to give a hard blast up the bypass and back then it went straght through the emissions test.
 
Ryan-EK9 said:
Considering its been sat for 4 months, the first thing I would do is go on the motorway and sit around 4000 rpm for about 20 mins and then get a retest. Do that before you start spending money on parts you may not need.
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X2

Older diesels and ones that are driven around town are the same too just need a good blast before testing :)
 
you need to give your car a good roasting before the test to heat up the cat
 
Thank you all for your advice.
But the back box will need to be replaced because it was effecting the emissions test due it leaking so no pass on the MOT test.
Also I suspect the head gasket may have gone. Four things lead me to suspect this
1. Brown looking coolant.
2. Bubbles in radiator filler cap.
3. Temperature gauge climbs when going over 4k rpm on high speed run, and goes back to normal once I go below that rpm range. Yet this does not happen during low speed normal driving.
4. Unable to get Oil dip stick out, Not sure this is due to gasket build up?

I will confirm gasket failure once I get my hands on a Combustion leak tester. Before deciding the fate of my Ej8.
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Ryan-EK9 said:
Yes and no. If the leak is behind the lamba sensor then it won't affect the readings, but it does if it's the other way round.
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i dont think so mate!, if there is a leak then it can suck in tiny amounts of air and mess the lambda reading up which is picked up by the probe of the gas analyser and not the lambda sensor on the car. again it can pass and sometimes not pass, it all dependes on the size of the leak.
 
Just get it sorted better to be safe than sorry. As far as an mot test is concerned depends on the tester and how the garage. Sometimes it is better to get a car service and mot
 
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