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CAN THE CAT CONVERTER BE USED TO ASSESS THE HEALTH OF THE ENGINE ?

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CAN THE CAT CONVERTER BE USED TO ASSESS THE HEALTH OF THE ENGINE ?

 
Old 03-09-2011, 03:50 PM
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964enthus
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Default CAN THE CAT CONVERTER BE USED TO ASSESS THE HEALTH OF THE ENGINE ?

from your experience ,could you tell a good engine from a not so good one by reading the results of an emissions 'test (CO/HC at idle speed in the UK)?
Or is it that even a bad engine will still show good emissions' results if the converter is in good shape ?
will a good converter eat whatever amount of oil going through it?
NB:Of course ,even a good engine will show bad results if the cat is dead !!
Peter
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Old 03-10-2011, 10:39 PM
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are you trying to asses a car from an emissions test?

i don't think you will be able to get relevent data to make that kind of determiniation.

A failed emission test could mean a number of things
a) the motor is bad
b) the valves need adjusting
c) the cat is dead
d) it was overfill with oil recently
e).....
hundreds of other things most are realtively minor

i don't know what you would classisfy as a bad engine?
- down on power
- top end
- etc.....

you can't tell conpression and cylinder leakage from an emissions test alone (good or bad)

but generally speaking if you have to do emissions the car should pass as a minimium otherwise you are inherting what ever repairs are need to get it to pass (same goes for the MOT)
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Old 03-11-2011, 04:41 AM
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Many thanks for your response :completely agree with what you say about failed emissions test and its numerous possible causes !!
What I am trying to get at ,is if by using the results of a "passed " test ,one could assess the health of an engine -or at least some parts of it
For example :
-would a worn cylinder ,or worn valve guides make it impossible to get below x% CO or x% HC?.
-would pollution by oil create a different pattern of test results than pollution by unburnt petrol?
If the methodology would work ,one could have sort of "threshold indicators"
just an idea to be shot at !
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Old 03-11-2011, 10:01 AM
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You can ruin a cat with something as simple as a bad O2 sensor.

Compression & Leak Down testing will give you the best idea of what is going on with an engine, that, along with a spirited test drive.
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Old 03-11-2011, 10:28 AM
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There is a lack of empirical data to to draw conclusions from.
No substitute for a good PPI.
By a well respected shop.
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