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Toyota Repair/2001 4Runner misfire code


QUESTION: I am getting a misfire code on cylinders 1, 2 and 5. The engine runs smooth.  I don't notice any change in power.  After resetting, same codes will pop up.  The mechanic can't find anything wrong.  What could it be?

ANSWER: Hello, the #2 and 5 cylinders are both fired by the coil on #5, #1 also fires #4 but there is no code for #4.
Have you tried replacing the spark plugs and the plug wires? these are very common failures on these engines other than the coils.  

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QUESTION: I tried replacing the plugs and wires before taking to a mechanic.  If 3 cylinders are misfiring shouldn't I notice?  The check engine light starts flashing at highway speeds.  It  won't stop flashing until I am at idle for a period of time.  If the misfiring is significant enough to cause the light to flash, I would expect it to be noticeable.

ANSWER: yes that makes sense, do you feel any vibration at that speed, like a tire balance issue that is bad enough to shake the steering wheel?
A misfire at higher speeds may not be noticeable but the computer may pick it up, try revving the engine to about 2000 rpm for a few minutes, sustain this for about 5 minutes and see if the check engine light turns on.

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QUESTION: I tried running the engine at 2000 rpm for 5 minutes.  There was no light.  There has been a few times that the light flashed at about 45 mph.  This has happened on some colder mornings after the car sat overnight.  I don't feel any vibration.  I did have the issue with tire balance in the past.  When that was the problem, the codes would change.  I am consistently getting cylinders 1, 2 and 5.  How does the ECM check for a misfire?

It checks via the crank angle sensor, a misfire will cause a deviation of the speed of the crankshaft, a misfiring cylinder will slow the crankshaft down maybe only  few rpm the computer  and matches this deviation with the cylinder that is firing and sets the code number. A vibration caused by something other than that can be picked up by the sensor and the interpreted as a misfire.

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Ted Ritter


I have more than 28 years experience as toyota technician, I will be able to answer most questions related to the Toyota product line up to the present year models,I am located in the US but welcome questions from other regions of the world. When asking a question please provide specific information: year,model, engine,transmission information. Provide as much information as possible including a brief repair history if possible. I have been a volunteer here for more ten years an have answered over 16,000 questions helping Toyota owners with their problems and save thousands of dollars without any compensation, some of my answers are published on many other websites including google and various automotive forums. DONATIONS ARE VERY MUCH APPRECIATED, IF YOU HAVE RECIEVED HELPFUL INFORMATION PLEASE MAKE A DONATION. AS OF TODAY (JULY 22, 2014) ALL REQUESTED GRAPHICS, ILLUSTRATIONS, DIAGRAMS, PHOTOS, WILL REQUIRE THE MINUMUM DONATION UP FRONT.


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