BiPolar r50

[m0nkeyprince]

Sometimes when I start my qx4, it idles really rough, feels like the engine is shaking like mad (could even feel it in the low gear shifter), RPM stable though. This happens on P and R, then when i put it into drive, it's smooth again like nothing happened, even if i go back into P or R.

What could be the problem? Ive had a distributor problem not too long ago, but i replaced the distributor.

[fueler]

ever change ur fuel filter? check plug wires? last time u changed the plugs?

[Chuck Tribolet]

It's unlikely to be the fuel filter. Fuel filter problems show up at high fuel flow raters, that is when you stand on the gas,
esp. at high RPMs, not at idle.

I'd start by pulling codes right after it happens, to see if there's a first failure code stored (which won't turn on the SES
light unit the second failure).

Does it happen hot? cold? both?

Chuck

[m0nkeyprince]

thanks for the replies!

my fuel filter is new, so is sparkplugs and wires

the problem only happens sometimes when i start up the car, and keeps on happening even on R then when I put it into D, it goes away, and afterwards, even when i put it back into R or P, it's completely normal

apparantly, I might have a vacuum leak

and i checked the for any codes, im green.

[m0nkeyprince]

So today it happened again, this time, even when i went onto D, the engine was still rough, though the RPM looked stable and i finally got a code

a P0305, a cylinder 5 misfire.

I doubt a leaking vacuum hose would cause that, am I right?

[Buzzman]

Just curious: is number 5 the spark plug that needs the special tool to get out?
Did you replace the plugs yourself?
I remember seeing a post or two on here where people supposedly had all the plugs changed (by someone else), only to discover that only five of them were actually replaced because they didn't have the tool, or were unaware of the existence of the tool (or were just plain lazy).
Might be something worth checking.

[m0nkeyprince]

I changed the sparkplugs myself not too long ago, and yes, even the infamous #6 plug, I changed it all with NGK Laser iridiums and NGK spark plug wires, which i checked yesterday all seem to be perfect, even the #5 sparkplug

After i cleared the code, and started the car, the problem was gone, so it's only a matter of time before the engine starts shaking hard when i start it