Emisions

Hi I have a 1995 p38 gems 4.6 and have had a complete new exhaust system replaced lamda sensors and it still won't get through emissions on a mot any ideas please

Air leaks between the maf and the lambda. Dodgy maf. Correct lambda sensors( Titania) early ones have a different plug. Are they switching? To rich to lean, misfires. Reset adaptive values?

Do you need to reset the adaptive values yourself or does the becm learn them after some journeys

The becm has no role in engine management it's the ecm behind the battery on a gems. It will adjust without any input over a few miles. Nano will reset all values but with test book I think it's possible to reset individual parameters. For example if your engine fueling has adapted to failing lambdas you only need to reset the fuel trims resetting the idle is unnecessary because you haven't changed anything connected with this( tps stepper etc) gems can be quite slow to adapt on its own to new realities. Reset is a good start.

Oh ok cheers I didn't know that still learning something new every day on these cars I just rembered they learnt some of the values and Mabey peterestart was taking the car back for mot before they had re set themselves

Peterestart said:

Hi I have a 1995 p38 gems 4.6 and have had a complete new exhaust system replaced lamda sensors and it still won't get through emissions on a mot any ideas please

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Air filter?

Four years on the trot I had emission trouble but I discovered sticky buns invariably compelled them to probe someone else's exhaust when I uttered "I'm going out for a smoke, don't expect me back for 15 minutes"
(That and whoring myself for the high altitude handbrake and steering shuffle!!) Worth it.