Rough Idle RPM?

Mellow77

Mellow77

New member
I'm getting a rough idle/vibration around 650 RPMs when the truck is warm. It's not a horrible rattle but it's enough that it gives a subtle drivetrain vibration I notice when at idle; anyone else have experience with this?

Rough Idle.jpg

Bump up the RPMs at all and it's smooth as butter again. Truck starts/runs great with 122K, no codes, no other symptoms or problems.

Smooth Idle.jpg

I don't have it hooked to a scangauge so I can't provide the actual RPMs this is occurring at but when I'm stopped at a light, in gear, I notice it until I change the RPMs or shift into neutral.
 

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Tell us about your maintenance, fuel filter? plugs/wires? tranny fluid ? Things of that nature.
 
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Truck is running all syntheic fluids except for in the tranny; haven't gotten to that yet. I can't find anywhere in the records (there weren't many) about fuel filter, plugs, wires or coil packs ever being changed.

I drive the truck about 300 miles a week so I'm constantly paying attention to what's going on with it and that's the only "gripe" I have. It's very subtle but it's a minor annoyance I just noticed. None of my passengers even notice it when I've asked.
 
01runner28 said:
My truck was doing that to, I cleaned my maf sensor and it was gone.
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Just cleaned my MAF last weekend along with Seafoaming my engine; no change. Changed the oil this weekend and also no change.

This didn't just pop up recently, it's just something I've noticed and wondered about.
 
Also, Its a good idea to change spark plugsafter you seafoam it. Plugs tend to get fouled up, and you dont want an electrode breaking off and falling into a cylinder.
Don't ask me how I know.
 
Did you ever figure out what caused that issue? I know this is years old but I'm having the same exact problem.
Thanks!
 
kjharper27 said:
Did you ever figure out what caused that issue? I know this is years old but I'm having the same exact problem.
Thanks!
Click to expand...

Having the same problem as well. Has gotten worse for me during my two years of ownership. My gas mileage has gone down as well. Don't know if the worse mileage and rough idle are related though.

The first thing I'm going to do is tear apart and clean the IAC valve. Have had new gaskets for awhile now. I just haven't gotten around to it yet. I've cleaned the MAF sensor before, but may hit it again.
 
Well! Cleaning the IAC valve and MAF sensor didn't change a thing for me. Still idles a little low and runs a little rough sometimes. Inconsistent though. Doesn't happen during every stop, which seems odd to me. Gonna try checking vacuum lines next.

BTW, How do you know if the IAC valve goes bad? Does it throw a code, run really bad or what?
 
A mechanic told me that my rough idle problem was caused by the EGR valve. not closing fully at idle. He told me he fixed it so it closed properly - which I did not know was possible. It idled nicely after that.

For a while. Now it idles poorly again most of the time but occasionally idles properly.
 
Noticed mine does this too.

Per the tach:
600 RPMS no AC, slightly rough idle
650 RPMS AC on- Idle is fine.

What is it supposed to idle off, no AC?
 
Mellow77 said:
Just cleaned my MAF last weekend along with Seafoaming my engine; no change. Changed the oil this weekend and also no change.

This didn't just pop up recently, it's just something I've noticed and wondered about.
Click to expand...

This thread is quite old at this point, but wanted to see if there was a solution to the idling issue?

I have an '04 V8 with 108K and am getting the same rough at idle at around 650 RPMs. Like with you, if RPMs go slightly up or down, the roughness goes away. Thanks in advance for any insights.
 
Same here - idle about 700 RPM in drive. When in neutral idle is smooth.
Also, in drive, if I bump up 100 to 200 RPM it smoothes out.
 
Steinmart said:
This thread is quite old at this point, but wanted to see if there was a solution to the idling issue?

I have an '04 V8 with 108K and am getting the same rough at idle at around 650 RPMs. Like with you, if RPMs go slightly up or down, the roughness goes away. Thanks in advance for any insights.
Click to expand...

[MENTION=212908]Steinmart[/MENTION]

You may want to try in the 4th gen section, you'll probably have better luck (this is the 3rd gen section so no V8's).

Good luck
 
Just wanted to update everyone: Took the 4Runner ('04 V8) to Toyota. They first cleaned the throttle body and the MAF but unfortunately didn't do the trick. I took the car back and they found a rusted heatshield that was apparently rubbing against the exhaust. That got fixed and the problem hasn't returned, knock wood.
 
EvilMole said:
BTW, How do you know if the IAC valve goes bad? Does it throw a code, run really bad or what?
Click to expand...

It’ll run poorly. I did a lot of looking-into this when I owned a Ford Ranger with an idle problem (turned out the problem was using an automatic ECU in a motor swap with a manual transmission). At least for that truck, a bad IAC or removal of it would make the engine stall and die if your vacuum system was not leaking. I don’t really know the ins-and-outs of a 3G Runner since I just bought my first one last month but I’d assume it’s the same. Run the truck, observe the idle, unplug the IAC and try to see if it idles differently.
 
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