scenic mot failure -emissions & brakes

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Thu 25 Jan 2007 20:14
scenic mot failure -emissions & brakes - damfine
today my renualt scenic 1.6 1998 failed it's mot,
on front brake imbalance 26% and exhaust co3 content failed after 2nd fast idle (excessive) along with lambda reading outside limits after 2nd fast idle test...
results .....
1st test co 2.144%
2nd test co 1.756%

lambda :
1st test .953
2nd test .963

i have been told by the garge to replace the cat but other people have just said it needs a good run and a bit of a service.. and for the brakes just strip the pads off and give the calipers a good clean!!!
if any body has a few pointers that would be great
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Thu 25 Jan 2007 20:27
scenic mot failure -emissions & brakes - Screwloose
damfine

It's interesting that the second fast idle test was so much lower than the first. How hot was the cat at this point? Had the car been sitting outside in the cold? A CO reading alone is not enough evidence to safely condemn a cat. A temperature differential and thorough live-data scan is needed too.

26% is a big difference in the front brake efficiency; had you noticed any pull to one side under braking? It could well be a seized component that will respond to a good strip and clean.
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Fri 26 Jan 2007 22:04
scenic mot failure -emissions & brakes - mark999
If a cat has failed there is usually some other fault that has caused it, so dont be tempted to change it untill you are sure.
Quite often the cat is ok but a faulty lambda sensor causes high emissions. It may be worth a visit to a dealer or specialist who can read any fault codes stored on the ECU.
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Sat 27 Jan 2007 09:57
scenic mot failure -emissions & brakes - Altea Ego
Damfine you are right, it does just need a damn good blow out out.

Just before the MOT, take it for a run on a dual carriageway, get it hot, then rev it hard a few times till the rev limiter cuts in to blow it out, then run it again on the dual cariageway at 4,500 rev MINIMUM. for at least 1 minute.


that will clean it out. and your co and lambda will be fine

The brakes however sound shot, you need them looked at by a garage

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TourVanMan TM < Ex RF >
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