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.

[madhornet]

i had a bad intake pipe on a couple of vehicles from the MAF sensor to the intake when the engine shifts the broken pipe was sucking air around the break instead of through the MAF so the ECU was confussed

[m0nkeyprince]

hmm, and that can cause the super rough idling? but the problem goes away after i put it into D gear, and after that the symptom wont show when i put it back into R or P. The problem only shows up sometimes after i start the engine and reverse

[pathfounder]

When you put it in drive, the engine shifts to one side, and when you put it in reverse, it shifts to the other. madhornet's suggestion makes a lot of sense. You could be closing a crack in a pipe by putting it in drive.

 

I would start it up, and jump out and start bending/flexing the inlet pipes and hoses that connect to it to see if any of them cause the engine to misbehave.

[m0nkeyprince]

When you put it in drive, the engine shifts to one side, and when you put it in reverse, it shifts to the other. madhornet's suggestion makes a lot of sense. You could be closing a crack in a pipe by putting it in drive.

 

I would start it up, and jump out and start bending/flexing the inlet pipes and hoses that connect to it to see if any of them cause the engine to misbehave.

 

thanks

 

ill check for any leaks, hmm im guessing soapy water wont work for vacuum leaks

[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?

[XPLORx4]

When was the last time your distributor cap/rotor, plug wires, and plugs were replaced?

 

BTW, check your PM's.

[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

[pathfounder]

The engine only has one knock sensor, so it can't throw a code for a specific cylinder. There's a good chance it has to do with #5's fuel injector because that is one of the only things that are detectable for a cylinder-specific misfire code.

[m0nkeyprince]

The engine only has one knock sensor, so it can't throw a code for a specific cylinder. There's a good chance it has to do with #5's fuel injector because that is one of the only things that are detectable for a cylinder-specific misfire code.

 

a P03XX is the general code for specific cylinder misfire, so since youre saying the 3.3's only knock sensor cannot detect cylinder specific misfires, that its most likely detecting a fuel injector problem? im a bit confused because if it's the fuel injectors, wouldnt the code be for that instead of a specific cylinder code?

 

anyways, ill throw in a bottle of techron fuel injector cleaner

 

and if youre right, would a fuel injector be hard to replace?

[ahardb0dy]

if you can get to the injector plug for the # 5 cylinder, next time it starts running rough try to listen to the injector using a long extension and see if you can hear it clicking

[Towncivilian]

Are you going to use the "Chevron Fuel Injector Cleaner" or "Chevron Techron Fuel System Cleaner"? Only the latter has PEA in it, which is what you want for good cleaning.

[pathfounder]

The #5 injector is in plain sight if I recall correctly. Not so on the other side of the engine (cyls 2,4,6).

 

The knock sensor isn't directional, so it can't "know" which cylinder had a misfire. I think it throws the "multiple cyl misfire" code, whatever code number that is.

 

The ECU will throw a specific cylinder misfire code for a (detectable) bad injector, along with a couple other things.

[m0nkeyprince]

The #5 injector is in plain sight if I recall correctly. Not so on the other side of the engine (cyls 2,4,6).

 

The knock sensor isn't directional, so it can't "know" which cylinder had a misfire. I think it throws the "multiple cyl misfire" code, whatever code number that is.

 

The ECU will throw a specific cylinder misfire code for a (detectable) bad injector, along with a couple other things.

 

thnk you

 

and thanks for the PEA tip towncivilian, i just got the fuel injector cleaner, ill look for the fuel system cleaner

[m0nkeyprince]

Just a thought, since the misfire code is for specifically cylinder #5, its not really a vacuum leak problem right? as a vacuum leak would affect all cylinders?