2006 Toyota RAV4 with 4-cyl 2.4L Camry engine, 138k miles. I have four problems. They may be related.
P0171 code – lean mixture. I have checked for the intake air leaks under the hood, and can’t find any. I have introduced Sea Foam into the intake twice. I have replaced the oxygen sensor, air filter, PCV valve and hose, MAF sensor, maybe something else. Didn’t help. The code is still there, and comes back after reset consistently.
The car starts badly in the morning. This problem has developed slowly over many months. It turns and turns but does not start. Then I wait a little, try again. After some coughing, it starts. I have replaced the battery and spark plugs (were worn out badly, running better now!), used Techron a lot in the gas. Didn’t help.
After long fast drive on the highways the car won’t start. Cranks and cranks, but it won’t start for up to half an hour no matter what in hot weather, maybe 15 or 20 min. in cool weather.
Almost always, after it is fully warmed, the engine hesitates quite a bit at the stop lights clearly due to the idle RPM too low, well under 500. It feels as if it is about to die; however, it never did. If I shift into neutral, the RPM rises to 600-700, and it idles perfectly. This hesitation slightly improved after I have replaced the spark plugs, but it is still bad.
What do you think can cause these things?