Espace Emissions Failure

[carmadgaz]

My neighbour has a 1999 2.0 Auto Renault Espace that needed an MOT after being stood for a while.

Had a few little niggles (bonnet wouldn't catch and temp fuel cap) and failed on the emissions (CO reading). Dead cat was our guess so we have changed the cat and sent it for a retest. Now the CO readings are higher than ever! The cat on the replacement part is a little smaller but the pipe appears to be the right size.

Any ideas on what we can do to get it through?

[davepoth]

CO means it's running rich. Look at the lambda sensor, MAF sensor etc. May be worth hooking it up to a fault code reader to see if anything gets thrown up.

[carmadgaz]

MAF sensor? Someone suggested the Lambda but I had dismissed it as the Lambda reading on the test was fine on the original MOT.

[ringram]

Has he taken it for a jolly good thrashing? Could be all coked up causing incomplete burn etc.
Give it a hiding and see what happens. If its misfiring or dodgy spark etc that might also be the cause.
If its been sat a while, check plugs, leads etc. Ideally check the o2 sensors are switching in closed loop etc.
(ie) Do a healthcheck and tune up on it. Go for a 2nd and 3rd gear blast up the motorway.