check compression low compression can cause a miss fire code if pressure is within specs get your self a hydrocarbon tester you suck antifreeze into it and if it changes color you have a bad head gasket,
BTW, I see this is an older thread don't you just love it when the original poster wants to pick brains but never replies as to what the final outcome was!!!!!

 

Is your check engine light on? If yes, what are the error codes?

Salim

 

i have same problem with 2001 rx300 but only on Bank 1, 1,3,5 cylinders misfire under load. idle is great Reste ecu, new fuel pump, new MAF new a/f and o2 sensors. Maybe i recently loss compression and will check it this weekend. to see if valve or cylinder is a problem. My gut tells me that it is a electronic control issue or vacuum problem. iwas driving for a year with rare misfire codes. but now I no longer have acceleration and cant get above 30 mph.

nick

 

OCV for bank one may need to checked.

Salim

 

1,3,5 misfire:....both OCV have been replaced, compression in 1,3,5 is 165-175 psi new fuel pump and new injectors.. unburned soot seen on spark plugs and in intake manifold. Since front 2,4,6 cylinder fire well I am moving theses coils to the back to see if misfire moves to the front (and front coils are simple to change. Will valve adjustment help?... Compression isnt bad. but not over 200 PSI either. Any suggestions Salim?

 

First going overt the basics .. 1,3,5 are the cylinders next to the firewall.

Two options come to mind.
1. Check the timing on the cams. Use a a phone camera to take the pictures of the cam marking as it is hard to get your head in position to verify the marks.

2. You can try swapping the OCV from one bank to the other.

Indications are that the issue is bank based and not individual cylinders so swapping coil packs will most likely not help. But if all three are bad then maybe.

Salim

 

replaced upstream cat converter and problem resolved. Never had bad milage until car had no more energy in higher gears. No just occasionally get evap codes. 0440s. Will tackle a leaking differential seal AWD next.