it´s a P38 with 4.6l and jsut 100k miles. GEMS-Ecu

CO levels are too high. At idle and raised RPM.
Engine does sound,well, not nice. It idles nicely, not rough, but just sounds not like other 4.6

OBD showed no! error, except something with O2-sensor initializing. The sensors have been changed (this system only has 2 sensors, instead of 2 additional sensors behind the cats). This reduced CO significantly (from 6% to 1%) but it´s still too high for the MOT test (0.3% asked).

Also changed were TPS and AMM.

Any idea ??

dirty air filter?
exhaust leak before the o2 sensors?

not trying to be a smart ass but you might want to check out the BB at rangerovers.net for this question. Gordo

Hi Gordo, this one ? http://www.rangerovers.net/forum/viewforum.php?f=3

Kyle, exhaust leak doesn´t seem to be there - as far as looking and feeling and watching could detect.

could camshaft wear cause sth. like this ? Would be somewhat premature in this case I guess. Spark plugs all do look similar, no fouling or glazing.
? if a camshaft is faulty, would a compression test reveal it ? That would fit my theory in that low RPM are no problem, while higher RPMs are.

The only definitive way to determine camshaft wear is to measure it either at the lifter bore or the rocker arm.

Everything else is indirect and subject to error.

Catalytic converter? They can break up inside or just stop working with age.

Catalytic converter? They can break up inside or just stop working with age.

I would expect this to also be accompanied by excess HC from the impaired efficiency of the cats.

I'm not well enough educated on exhaust gas analysis to say much more on the subject.

HC levels go through the roof when your cats are shot. Can make a disco’s exhaust smell like a Series I’s!