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MG MGF Technical - strange emissions

hi , can anyone shed some light on this , took my 96 mgf (jap import)for its mot and went sailing through till it came to the emissions , co2 is reading virtually 0% hydrocarbons are just about 0% but the o2 is reading 4% sometimes more . 3 different garages and nobody has a clue , tried a new lamda sensor , no holes in the exhaust , no air leaks on the induction , new plugs/dizzy cap /rotor arm ,K&N filter cleaned ,cams checked ( to make sure they havent jumped a tooth)nothing,,, everything checks out ok ,,i need to get it sorted the nasty mot man will not let me play in it anymore !!!
stu

Doesn't the Japanese spec MGF have two sensors?

Stu - join the club (it is free) and do an archive search, I am sure you will find information there.
Ted Newman

Normally a high o2 reading is due to the following: Vacuum leaks,ignition problem and possibly a duff catalyst. In your posting most of these have been ruled out by the garages.
Do they measure the lambda value at U.K MoT ? This is a good indicator too on what´s wrong. Probably you have a high lambda in the region of 1,05 or even more..
This means that there is either an air-leak somewhere or the engine is running lean for some other reason.
Also be aware that on the F as on many other 2-outlet cars there can be a diff. in readings depending on wich exthaust outlet that is being used!
If possible come back with a lambda reading. / Carl.
Carl

Yes, Lambda is measured as part of the MoT Carl - and I agree that this would shed significant light on these emissions findings.

I suspect that an exhaust leak is the most likely explanation - and although various garages have failed to find it, it is IMO still the most likely explanation.

Check everywhere from the manifold gasket on the cylinder head to the tail pipe.
Rob Bell

They should stuff the probe in a long way and block the other exhaust with a rag - failure to do this can lead to the exhaust sucking in air as it rumbles and giving a high reading.
Will Munns

Will,that was one of the funniest comments on this board for years !
Noname

is it ?
:-/
Dieter

This thread was discussed between 23/05/2006 and 24/05/2006

MG MGF Technical index

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