Sunday, May 13, 2012

2000 Toyota Avalon: Engine Lean Codes and Knock Sound on Acceleration?

On this vehicle Engine lean codes related to oxygen sensors comes up also the Engine makes loud knocking sound when Accelerated.

What grade or octane fuel are you predominately using?
Its Advisable to use 93 octane fuel.

Its the problem related to ECM( computer),the Knock Sensors,the MAF sensor too.

Also the oxygen sensors needs to be inspected,if faulty then it has to be replaced.There are 4 oxygen sensors.Two are before cat converter and 2 are after cat converter.

What you're going to find is that with the knock sensor for bank two setting a code the computer cannot dial back the ignition timing when there is detonation. You typically will not hear detonation on any Toyota engines due to the efficient knock sensors. However when you lose one the computer can no longer control the ignition timing and you will get detonation even with 93 octane is just less noticeable. Regarding the lean condition code P0171 provided you do not have an air fuel ratio sensor or oxygen sensor that is going out of range but yet not setting a code 90% of the time this ends up being a contaminated mass airflow sensor. If you remove the mass airflow sensor and look down into the tube with a flashlight you'll see two tiny resistors they get coated with grit and dirt and drive the system lean. This is the first place to start. Use mass airflow sensor cleaner or brake cleaner then blow dry. Do not touch these wires with anything you will break them. Remove the negative battery cable to reset the fuel control system that drive the vehicle. If you have a scan tool that monitors live data list monitor the air fuel ratio sensors. They need to be at about 3.3 V and the fuel trim should not exceed more than plus or -5%. Have oxygen sensors depending on your production they will toggle between .1 V and .9 V about eight times in 1 min.

The fuel pressure could be an issue. To confirm this test the voltage,you need to be at about 35 PSI minimum. If the fuel filter is never been replaced that could restrict fuel flow and also cause a lean condition but usually that will be attributed to a cylinder misfire also. It classifies it as P0171 which is just a lean condition code bank one or bank two doesn't matter. They did start isolating bank two with its own lean condition code until later years.

This details will help.

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1 comment:

  1. The engine would be nice if upgraded or enhance to have a better performance.