Hello all. This is my first post. I am hoping to get some feed back in hopes that I can figure out whats gooing on with my daughters car.

I'm am not a car technician. I try and keep the family cars running as best I can using YouTube and forums. I am a telecommunications technician so I have the ability to logically troubleshoot a lot of the troubles I find with our cars. I'm not very familiar with Lexus products so I am here asking for some assistance. Thank you in advance for any and all help you guys can offer!

My daughter said her car was acting funny. Took it for a test drive and the car was hesitating, sputtering and had a small backfire. Pulled the codes and got a P0171, 174, 300, 306. I originally thought that it was an air/fuel problem and since I had the P0300/306 I started by getting the throttle body out the way so I can look at the spark plugs. Once I pulled the throttle body I noticed coolant buildup on the engine on the passenger side to the right of the exhaust manifold. Once I saw that I started looking for coolant in the more obvious places. I noticed coolant buildup around the top side radiator hose and it looks like the coolant fill reservoir is filling up and coolant is seeping from the fill reservoir cap as there is dried coolant on top of the fill tank and down the side and rear of the tank. I will include the pictures. Her car does not overheat. The gauge stays in the middle but before I start chasing air/fuel trouble, I felt like maybe the cooling system should be addressed, so I turned to this forum. Any suggestions?

Thanks again for any help!

Passenger side exhaust manifold

Closer view

Better view

Radiator hose and coolant reservoir

 

Maybe just needs new spark plugs. At least that's the first thing that came to mind, I don't know if you actually looked at them or not. I had a similar problem relating to the leaking coolant though, turned out to be the water pump itself(I also changed the radiator since it had never been replaced as well when I got the the car as well). I'd also check the water bypass outlet of the water pump, tends leak from there if the seals never been changed. Hope this helps, best of luck

 

The upper hose could use a clean up and re-clamp. Use a hose clamp rather than the old spring tension one. It's weak and no good anymore. The first pics are of a block drain. Not sure why there is build up there. But you may need to find a plug with the same threads and loc-tight and cap it off. Maybe the drain has rusted out.

P0171 and P0174 are related to the system running lean, and they are likely the cause of the misfire codes. Not to say it doesn't need plugs and a good tube up. The majority of the time it is a vacuum leak or un-metered air leak around or past the MAF. Inspect the airbox, intake tubes, and resonator box for any cracks, holes, missing clamps, or disconnected hoses or any cracks/ holes in them as well. Also use some MAF cleaner to clean the MAF. You will want to clean the gunk and carbon build up out of the throttle as well while you have it off.

Now that yo have it apart, I'd do the plugs and wires. And go back together with a clean throttle and MAF, then do the battery disconnect and computer reset method. Fix any problems you find along the way. Will be running way better once these things are replaced and cleaned up I'm sure. But if you don't find a problem in the intake, you will have to check for vacuum leaks past the throttle and to the engine, and you need it running to do that. But check the intake system first and clean two items mentioned well. Let us know if it solves the problem.

 

That one on the block is to drain the coolant from the block. snug it up a little. The overflow bottles always leak especially if aftermarket. Changing spark plug a PIA on your engine. People throw out guesses, check the muffler bearings also while your at it.