I've read nearly all of the rough idle posts pertaining to my year 4runner and similar year Tacoma. All to conclude that no one really knows the cause. The motor was just swapped over (just the block) did end up needing a new knock sensor wire but feel that's unrelated. My question is what electrical component controls the idle? I hate to shoot in the dark and just start replacing crap if um
unecesary, yes the motor is elec. Components are older 245k ish (what hasn't already been replaced). Anyone actually fix this rough idle? The last code I got was for the front o2 sensor (replaced 12/9) and a missfire on cyl 1&5 (a coil pack perhaps?). Help as always will be greatly appreciated.

A

 

No one?

 

Not sure on the 3.4L, but I do know that the IAC (Idle Air Control Valve) can be the culprit for Chevy's with the problem you are describing. Are you sure its cleaned and functioning properly? It controls idle electronically. It also could be dead if the AC is causing a higher load and not adjusting idle correctly...

A misfire on two adjoining cylinders would say a coil pack... but 1 and 5 wouldn't make much sense...

 

First thing to keep in mind is you are posting at 9:30 and 11:00am on a work day - it may be tonight before a lot of people are able to come on the board and post.
Just to keep that in perspective.

Have you done a full tune-up recently? Clean the MAF? TB? Replace plugs? How long as it been having the problem? Tried higher octane fuel? Etc...

Fink

 

I have a front O2 to swap in but waiting because they cannot be returned, I spritzed the MAF but should look at throttle body.
Recent motor swap has left me with a rough idle, it was just the block that was swapped (of course).
Air filter cleaned and lightly oiled every 30k
Fuel filter 20k
Plugs OE 20K
Wires OE 20K
Front O2 Dec of 2009 likely 20k
Rear O2 controlled by simulator
Knock sensor 245K
Knock sensor wiring OE NEW
MAF 245K
PCV within the last year
EGR NFK? No freakin clue if replaced or exists
Have checked and rechecked vac. hoses and found one with a crack but not near where the hose inserts, (the tube inserts well past the cracked hose portion).

What else is there?

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I would try running some fuel injector cleaner through it and maybe try a higher octane fuel to see if it gets better/worse.

Have you replaced the fuel filter?

Fink

 

Updated the list!

 

Mine was doing this a couple days ago. The RPM's would drop down to about 400-500 @ stop lights, and if I turned the A/C on at a light it would surge up and down, up and down. This thread and this thread helped me the most. Pull apart your IAC and you'll see it will be all gummed up with black stuff. Clean it out with brake cleaner. You may need to wiggle the plate around to get everything. I didn't need to pull the sensor off, just the 4 screws that hold the part to the intake. Worked for me, idling smoothly again . All in all, 45 min. job taking your time.

I will be doing this to any 3.4L I get in the future during my cleaning regimen.

 

Gentlemen thank you for your thoughts and ideas but this may en up being a cam not zeroed during the initial setup. I will keep you posted!

 

In fact it was a un zeroed cam, the pass. side was off by one tooth and caused crazy timing.

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EDIT!!! I found it on the thread connected to a couple others!


Is that on the intake tube?

 

Really? No since the 5VZFE is a twin cam the cam pulley (insert technical term here) are set to dead center (both of them and the fly wheel thing on the bottom is also set to zero) there is no timing adjustment to be made. I recently had a motor rebuilt and during the swap of parts from one block to the next the cam was not aligned properly.

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