2006 4Runner V8 slight rough idle/sputtering

P

paweliania

Member
Hello all,
Ive searched to no avail. My truck has been sputtering at idle while stopped in gear. It eventually threw a P0101 code which is the Mass Air Flow sensor. I first cleaned it then finally replaced it. I then cleaned the Throttle Body and it is still doing it. Seems to do it after its been warmed up and only in gear. AC is can be on or off and it still does it. It hovers at just over 5K RPMs and will raise and lower when its happening. first you'll feel a slight sputter and then maybe a few in a row. Ive inspected the intake hose for cracks and was not able to find anything. Should I replace the spark plugs? What can this be?
 
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paweliania said:
Hello all,
Ive searched to no avail. My truck has been sputtering at idle while stopped in gear. It eventually threw a P0101 code which is the Mass Air Flow sensor. I first cleaned it then finally replaced it. I then cleaned the Throttle Body and it is still doing it. Seems to do it after its been warmed up and only in gear. AC is can be on or off and it still does it. It hovers at just over 5K RPMs and will raise and lower when its happening. first you'll feel a slight sputter and then maybe a few in a row. Ive inspected the intake hose for cracks and was not able to find anything. Should I replace the spark plugs? What can this be?
Click to expand...

Have you tried disconnecting battery for about 10-30 mins (or whatever time it needs to lose memory) and letting it relearn the idle?
 
How many miles, has it ever been tuned up before? Has the pcv valve been changed etc.....

If not it should be done. Toyota recommends plugs at 100k. Since its 14 years old I would change all vacuum lines. I did this last month and even though they looked good, it ran much better when they got changed. Got them all from toyota.

Also check O2 sensors. Even though they aren't throwing a code they could still be failing.
 
It has roughly 225,000 miles. PCV valve has never been replaced as far as I know. What are the symptoms of a bad PCV valve? Im ordering one from amazon now...

Ill look into the vacuum lines. Which O2 sensor could be causing these symptoms?
 
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A bad pcv can cause the issues you are having or worse, stalling, blow by, oil consumption etc...

It would be the upstream sensors, get the DENSO ones only. They are OEM toyota and my opinion are the ones to use.

You could use aftermarket vacuum lines but some of them are preformed and the aftermarket lines will kink unless they are made longer. The toyota ones are the exact correct length and are preformed.

Also there is a vacuum line that is tough to get to so its often overlooked. It is attached to the bottom of the front of the intake manifold plenum. Its on the rt side front. It might be cracked or fell off.
 
inscarguy said:
How many miles, has it ever been tuned up before? Has the pcv valve been changed etc.....

If not it should be done. Toyota recommends plugs at 100k. Since its 14 years old I would change all vacuum lines. I did this last month and even though they looked good, it ran much better when they got changed. Got them all from toyota.

Also check O2 sensors. Even though they aren't throwing a code they could still be failing.
Click to expand...

Any chance you have part numbers of all the lines you replaced?
 
Don't forget to clean the throttle body as well. Brake cleaner on a rag and open the butterfly by hand and clean as much of the shit outta there you can get, top and bottom.

Oops, missed that you had cleaned it already, sorry about that.
 
Did the spark plugs yesterday and truck seems to be running great. Drove it yesterday for quite a bit and hasn’t done the sputtering yet. Still planning on replacing the PCV valve. Thank you all for your responses. I’ll report back if it does it again otherwise cleaning the throttle body, replacing the air filter, replacing The MAF, and spark plugs seemed to fix the issue.
 
paweliania said:
Did the spark plugs yesterday and truck seems to be running great. Drove it yesterday for quite a bit and hasn’t done the sputtering yet. Still planning on replacing the PCV valve. Thank you all for your responses. I’ll report back if it does it again otherwise cleaning the throttle body, replacing the air filter, replacing The MAF, and spark plugs seemed to fix the issue.
Click to expand...

Were all the old plugs the same brand or 2 different brands?
 
The PCV is a simple valve with a round ball and a spring. It can easily be cleaned using brake parts cleaner by shooting some cleaner into it. After a while you should be able to shake the thing and hear the ball rattle. That's it, it's clean. This is a five min job at most.

Do replace the vac hoses as the ends become hardened and split over time. You can also snip the end off then slip it back on to the device it was connected to. But, if the hoses feel hard then it should be replaced.
 
See you got it fixed... nice.

I was going to mention too that the ignition coils seem to deteriorate and crack/split with age, been a couple reports on the forum.
Causing idle issues.
 
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