2003 LS430 P0011 P0021 P0300 Multiple Random Misfires
 

Symptoms: Car shakes a little bit, has a rough idle, and the throttle feels poor/sluggish.

There are a whole slew of codes

P0011 camshaft timing advanced or retard - system bank 1
P0021 camshaft timing advanced or retard - system bank 2
P0300 multiple/random misfires
P0301 misfire in cyl 1
P0303 misfire in cyl 3
P0305 misfire in cyl 5
P0306 misfire in cyl 6
P0307 misfire in cyl 7
P0308 misfire in cyl 8

I tried replacing the left and right OCV to solve P0011 and P0021 but that didn't really solve the problem. Engine shakes a lot less but it is still misfiring and all the codes are still present.

Somewhat stumped as what to do next... Can anyone please give me some suggestions?

I'd check the timing belt has a proper tension and not skipped.

I would start by checking out the camshaft position sensors. Check that the wires are still good, and measure resistance across both sensors. Resistance spec is 835-1400 Ohms when cold, and 1060-1645 Ohms when hot.

What is the status of your timing belt, very old, recently changed, or in between? Sounds like it might have jumped a tooth.

Aside from the camshaft timing codes, I saw the same thing on a 99-02 Honda Accord V6. Lots of Google searching yielded all kinds of different answers, as these random misfires and failure to start on a hot soak were very common to this generation of Honda V6 engines, and lots of people tried everything and still couldn't solve it.

I eventually solved the random misfires by one of more of the following: new fuel injectors (including diagnosing one faulty "new" injector), new ignition coils, new spark plugs, new fuel pulsation damper (LS430 has 2 of these) and/or fuel pressure regulators, new engine coolant temperature sender, and resetting the ECU and doing a special relearn procedure involving driving around at certain rpms at certain speeds for certain durations. I might have even installed a new battery. Not saying this will help with the LS430, just saying it helped with the Accord V6 engine with the same codes. These items are easy enough to try and not too expensive in parts, and labor is free if you do it yourself :)

Have you got a techstream/vci cable? If so there are a few tests that can be run in isolation - such as fuel injector tests and some VVT oil control valve tests to name a couple form the top of my head.

As for misfires, have you pulled each coil out to look down each of the spark plug wells to see if there is water or oil in there? And/or suggest pulling a sparkplug or two to check the colour of the burn.