nissan misfire?

Question

i have a 94 nissan maxima 3.0 dohc that has a weird low rpm misfire. it seems to go away above 2000rpms.
when you disconnect the fuel injector the idle gets rougher.
but when connect back in the roughness goes away a lilttle bit.

but when you removed the coil (on top of sparkplug) the idle does'nt change.

the coil is fine. it sparks and my spark plug is black. and there seems to be a rich smell from the exhaust.....

anyone have any suggestions??

t.i.a

update to all yall answers...thanks btw,
has new plugs, filter, mass air flow, fpr, a few injectors.

i moved the coil to see if the missfire follwed it did'nt it stayed in the same cylinder.

Answer 1

You should definately try replacing the coil, they are different from front head to rear head, if it is a rear cyl. head coil make sure the coil extender is not leaking, coils are common on this engine.

There no ignition wires on this engine, no disrespect Polkan47, if there were you would have a very valid point though, thx.

if the misfire stayed in the same cyl. then you must have either a bad spark plug, low compression on that cyl., intake air leak on that cyl., faulty injector on that cyl.., or a cam or valve problem, I doubt any mechanical problem(internal that is), I am sure the answer is probably simple.

probably a bad plug!
these engines are very moody when it comes to the spark plugs, I hope that you are using the proper spark plug!, not some Bosch platinum AZ garbage!

Answer 2

At first i was going to agree with one of the others answers. But if you are smelling gas from the exhaust then it sounds like it is running rich. Could be that you need new spark plugs since of the misfire you would smell a rich smell from the exhaust. Or maybe a spark plug wire.

Answer 3

replace air filter

replace spark plugs

replace spark plug wires

replace cap and rotor

replace mass air flow sensor

replace fuel pressure regulator

Answer 4

I would change ignition wires to.