MOT Failure, Emmissions....

My V8 has failed hurrendusly on emmisions (and brakes but i can fix that), they recon it has a miss fire. I know nothing of petrol engines. Where should i start, spark plugs and leads?

Rich.

service the injun.Oil, filters etc and you should get through.Also use good petrol(ie not from super markets) for the test.Maybe a bit of injector clear will help too.

Do the basics first. Plugs and leads. If you have a missfire unburnt fuel will get thrown down the exhaust hence your high emmisions. What vehicle are we talking about here?

Another thing vould be one of the HEGO sensors. Thats the things screwed into your exhausts just before the cats. Dear to buy new but I got a pair from a breakers for a fraction. Sorted it right away. (Still have to fix a misfire on the other P38 though).

Thanks guys just doing the online order now. There are two different sets of leads depending on age, and my engine isnt origional to the chassis, so cant go by the chassis number. Any ideas how to tell which set ive got?

Edit: Sorted now.

The newer of the two engines (1998 on) has a pair of small water pipes going to the throttle housing. The Gems engine (94-98) doesn't! There are other differences but that's the quickest to spot. Another point is that the newer one has less space down the back to stick your hand when changing the leads.