This problem started happening a month ago. It only happens sometimes. I'll start driving and after 10 or 15 minutes I'll come to a stop light or I'll be driving at low speed. The checkengine light will then come on and I'll notice the engine is idling rough with lower RPM. The VSC and Trac Off lights also come on. It usually goes away after a few minutes of idle or when the engine has cooled off and that is an important clue.
The misfire OBD codes are all on the same side of the engine (cylinder 2,4,6). The codes are: P0021 (Bank 2 camshaft position), P0300 (multiple misfire), P302, 304, 306 (misfires for cylinder 2 4 and 6). Yesterday when this issue was active, I disconnected all the spark plug connections on that side for cylinder 2,4,6 and there was no difference. This means all those 3 cylinders were inactive.
So its a binary problem that comes on and off again. That rules out certain things such as spark plugs and coils going bad at the same time. It has to be something else. For one side of the engine being inactive, from what I've learnt by reading online, here are some possibilities:
- Vacuum related valves, PCV, EGR valve clogged/blocked, Distributor, Compression tests, ignition checks, crankshaft position sensor, Valve adjustments, fuel issues (check fuel trims for both banks)
- Ruled out: Wires to O2 sensors

What is it that triggers in the engine after 15 minutes of idle and becomes inactive when the engine has cooled off?

Does anyone know what could be wrong? If it matters, this is for a Lexus ES300 2002.

 

How many miles? I've said this many times #1 suspect is the oil control valves also the screens get clogged.

 

+1 For oil control valve.
And for the future yea please include year make model.

 

Thanks guys! You're right, I searched about that now and yes that might be it, although I havent seen a P1349 code on it. I assume this issue can happen without the code being triggered. Its a Lexus ES300 2002 as I mentioned in my first post. It has 142K miles on it. I bought it at 99K.

 

That is correct. I actually had this problem on my 99 around 170k First it was bank 2 then bank 1 followed about 10k miles later just showing the misfire codes.

 

I usually change my oil at 7K miles but this time I got lazy and it had been 8400 miles and almost 2 years since the last oil change. I checked the oil yesterday and it was below the low mark. So I got the oil changed yesterday and the mechanic said that might fix it. The issue is still there. I wonder if the oil got so low that the sludge came up and blocked the oil control valves. I also expected the oil light to come on if the level was low but it didnt. From now on I should check my oil at least once every 6 months.
I'll wait a few days and if the problem is still there, I should get both valves replaced and the screens cleaned.
I wish I could do this on my own but I dont have enough stamina or the right tools to do stuff like this. From what I saw, this is one of the easier things to fix as everything is near the top. This weekend I might attempt to pull out bank 2's valve and see its condition. I think the valve for bank 1 is harder to get to.
Is this easy to do or should I get it done at the auto shop?

 

Indeed that was the problem. The auto shop replaced the OCV's and that fixed the problem. Thanks all.
He should also have checked/cleaned the OCV's screens/filters but he didnt know they existed. Works for now.