engine probs egr ?

[scottishstu]

hi guys not a nova question my othe car vectra as i know a lot of you change the engines so hopefully use can help? its a 2.0 16v ecotec its running like a cow the now ive replaced the coil pack mass air flow and another sensor cant remeber the name the one next to exhaust manifold anyway i replaced the plugs and oil about a week ago and it ran ok for a day or two,then started again took the plugs out and there blk sometimes get a back fire to any ideas?
thanks
stuart

[scottishstu]

or do you think the cat knacked or egr valve?

[jimbob-mcgrew]

black sooty plugs probably means its over-fueling.
if youve changed the air flow meter recently with no joy, maybe look into checking the connection on the lamda sensor (exhaust downpipe). the airflow meter measures whats going in and the lamda measures it out, and both sets of info get sent to the ecu and it calculates the fueling acordingly. check that sensors plugged in allright and doesnt have corroded contacts or anything. maybe if still no luck, unscrew it from the exhaust pipe and give it a good clean up, might help. vectra's are loaded in sensors, and they often die, can be tricky to find which ones causing the prob. friend of mine ran a test on his a while back it came up with 3 dead sensors, cam, crank, and something else. didnt run too bad tho considering, tis a shame his clutch was burnt out to crap and slipping all over the road like an old morris minor trying to haul a piano up a hill.

[AlexW]

Is the EML on?

Plus may appear black due to overfueling when cold.

May be worth changing the CTS too.

Altho you havnt really told us the fault.