armystrong928

ok when i let my suburban idle for a few min it throws a ses light and it comes up as p0305(misfire cylinder 5) ive been fighting this code for a while it use to stay on all the time. i have done plugs, wires, cap, rotor, fuel filter, and MFI coversion on the injectors. i know when i hit the gas hard while moving the light goes off. when it is setting still like parked it comes back on. I was thinking it could be the o2 sensor on the driver side but not sure. does anyone have any ideas?

kevinkpk

could be the injector

armystrong928

injectors are brand new

shamrock246

whats the compression on that cyl and the other ones next to it?

armystrong928

not sure but it wouldn't be just throwing the code only when idles if its from a valve. only ideas i can think of are the o2 sensors and the egr.

MDTAHOE

You need to compression check it . O2 sensor or EGR will not cause a single cylinder misfire.

armystrong928

last i checked about a month ago on compression it was all within 5-10 psi difference which is good which is why im leaning toward o2 sensors and egr cause at higher rpms they work harder.

bdburb

Could be intake gaskets. Was the plug out of #5 all gunked up with carbon or a whitish substance?

MDTAHOE

Again o2 and EGR will NOT cause a single cylinder misfire!

kevinkpk

What does the plug look like? Single cylinder misfire is something specific to that cylinder, i.e plug, injector.