TimYang

Folks,

I have a 2000 Lexus ES300 that my daughter drives to school and on mostly short trips around town. It has 201k miles on it and it had the timing belt and plugs changed about a year ago along with some motor mounts and suspension hardware. Since that time I have nad a radiator changed but no other maintenance except and oil change. It hesitates during acceleration and the fuel mileage is around 10-12 mpg. I've changed 3 ignition coils and the rear bank OCT valve. I have a little oil (a few drops) in the upper intake manifold and a little coolant (a few tables spoons) Today I cleared the CEL codes and tomorrow will recheck them. I hope to no long have misfire codes on the cylinders where I changed the coils and I hope the P1349 code is gone too. There used to be a rough idle but that seems to have cleared up.

At this point I am wondering about a crack in a vacuum hose or one of the intake hoses, how big of a crack does it take to leak enough air to cause problems? I don't think it is transmission related but I am thinking about changing the ATF to see if that makes a difference. I have read about a vacuum canister leak issue but I have to admit that I don't know much about that system. I can add more details if anyone has questions that could help me diagnose this. I will list the codes tomorrow but I wanted to at least get these thoughts out tonight.

Thanks in advance for any help,

-Tim

Richardsr

If you have oil and coolant puddled up on topside, it sounds like a head gasket. Maybe drain your oil and check for water there.

Coldax

Have you ever cleaned or replaced the Mass Air Flow (MAF) sensor? What about the fuel filter - has that ever been replaced?

TimYang

Cleaning the MAF sensor and throttle body helped a ton. I need to think about the fuel filter but for now I will let my daughter drive it for a week or two and see what happens. I did clean the linkage for the throttle cable and probably shouldn't have. I think i clean lubricant off areas that need lubrication because the throttle feels stiff coming out of a stop at a traffic light etc....

Cpthaddock

We need to know what codes are popping up. A rough idle can have endless possibilities.

Try spraying some brake cleaner around intake and vacuum hoses while the engine is running. If the engine rpm changes then you have a hose problem.

a bad vvt solenoid will also give you a rough idle. I would wait until the engine is running poorly and I would unplug the vvt solenoid to see if there’s a change. No change could mean that solenoid is failing.


lots of other possibilities.