Hi all,
I have a concern with my lexus rx 450h 2010 model. I drove it a lot and raised it to 325k. Recently it start showing random misfiring and then it shows cylinder 6 misfiring. Hence, i cahnged cy, 8 spark plug and it worked well but in a day or two it shows cylinder 2 and i changed that too. But it behaves same even after all the trouble.
when i start it all seems ok but after few min it idle and then it start shaking the engine and change sound and seems misfiring but if i press gas it stops and gets normal. Additionally, its good while the rpm are higher and not idle no loos of power ir anything.
Does anyone experienced it? please help.

 

I don't know much about these newer vehicles but if you changing one plug you should be changing them all.
I would change all the plugs and all the coils. Of course you have already changed a couple of plugs so they shouldn't need changing.
I did find a video that shows just how intensive such simple job is.

 

How is it that you changed #8 spark plug in a 6 cylinder engine? Surely that's a typo? Anyhow, as mentioned by Dave, all six spark plugs should have been changed out. And do not use spark plugs purchased from eBay or other online stores as there are tons of fake spark plugs out there.

If it's not the spark plugs then it's the fuel injectors. They have a tendency to get covered in carbon due to the EGR system recycling exhaust gases back through the intake manifold.

Given that the engine runs fine at higher revs, I suspect the injectors are the culprit, not the spark plugs.

Check out this discussion thread: https://www.clublexus.com/forums/hyb...anty-work.html