help misfiring at idle tried some stuff

[singlecamslam]

I have a completely unabused 240sx with a twin cam that i just bought from the original owner. The car has been sitting for a while. The problem is the car runs perfectly driving, but at idle its misfiring and the whole car shakes. I changed spark plugs, cap, rotor changed the spark plug well gasket because oil was pooling up on the plugs.

This did absolutely nothing, car runs like a dream driving, no stumbles no misfiring, at idle it shakes and misfires. No vacum leaks, timing is dead on 20 degrees.

Things i havent done:
new coil, o2 sensor, injectors? I'm not that good at trouble shooting, give me some ideas guys and i'll start checking. The car is in immaculate condition, so i'm kinda lost on what it can be. No check engine codes.

[singlecamslam]

Just checked the plugs, they look brand new, no discoloration or nothing. I will try putting each plug to the block and checking for irregular spark, give me som ideas please.

[CrimsonRockett]

Try replacing the spark plug wires by any chance?

Had an old 97 Altima(DOHC KA) that also stumbled at idle. Swapped out the spark plug wires with NGK's and the problem went away.

[singlecamslam]

Put new wires from a known good running car, next will try replacing the coil with known good one, than i run out of ideas.

[smbonn2005]

Had close to same problem. Should be a stuck open injector or intermittently stuck open injector that is semi flooding the engine

[singlecamslam]

Gonna try the injectors next than, just put new gas, new coil, new wires, did nothing. The misfiring is very random and i cant tell what cylinder it is, and it is also a slight misfire, since i have a spare car i'm going to just pull the rail and see what happens, will report later.

[army240]

IAC/AAC Valve? If you press gently on the throttle plate, like rpm going up 500rpm, does it still do that? I'm really not a kingpin with KA, but if the problem is with the idle, i'll check the idle valve...

Frank

[singlecamslam]

Had close to same problem. Should be a stuck open injector or intermittently stuck open injector that is semi flooding the engine

owe you a beer. One of the injector seals was torn causing extra air to get into the combustion chamber, replaced, bam, runs smooth. Thank you!

[SoguRacing]

haha so it was a vacuum leak

[steve shadows]

Its always a vacuum leak or timing

timing timing timing timing timing

[doomviillain]

owe you a beer. One of the injector seals was torn causing extra air to get into the combustion chamber, replaced, bam, runs smooth. Thank you!

hmmm. i have sort of the same problem with my single cam. a little rumbly at idle but runs smooth. i may have to do that. did you buy them new or used and how much