2006 v8 low/ cycling idle

[lightemup67]

So only after the engine is fully warmed up, the idle on my v8 drops to around 500 RPMs when I'm in drive with my foot on the brake (at a stop light). It doesn't happen when the engine is cold. It also kind of "cycles" in and out of it. The computer will kind of "click" and the idle will return to normal ~750 RPMs. Then after a few seconds, it'll drop again to 500. (See the video)https://youtu.be/nOg8D-GQ58s

The 4runner has 115,000 miles on it, and is in generally good shape. I've cleaned the MAF sensor and throttle body and unhooked the battery for 30min+ to clear the computer.

It has never thrown any codes or lights, and generally runs really well. It seems different than some of the other threads I've seen on this. Usually there are CELs or codes to check out. Any ideas on what else to try?

 

[Inv4drZm]

Turn off the AC and see if it still does it.

 

[nevada]

is the ac on? or the mode selector set to defrost?

 

[thecole1098]

It’s the AC cycling... mine does the same thing.

 

[mpyle]

Mine does the same thing and picks up enough rpms that it will move the truck if I don't have my foot on the brake.

 

[lightemup67]

Definitely happens when the AC is off as well. It does seem like that sort of "cycling" though.

But now that I think of it, the AC has been blowing warmer lately. I guess it could be related, but its weird that the idle symptoms happen with AC off.

 

[nevada]

Definitely happens when the AC is off as well. It does seem like that sort of "cycling" though.

But now that I think of it, the AC has been blowing warmer lately. I guess it could be related, but its weird that the idle symptoms happen with AC off.

where is the mode selector? if its in any defrost position it will also cycle the compressor.

 

[AuSeeker]

So only after the engine is fully warmed up, the idle on my v8 drops to around 500 RPMs when I'm in drive with my foot on the brake (at a stop light). It doesn't happen when the engine is cold. It also kind of "cycles" in and out of it. The computer will kind of "click" and the idle will return to normal ~750 RPMs. Then after a few seconds, it'll drop again to 500. (See the video)https://youtu.be/nOg8D-GQ58s

The 4runner has 115,000 miles on it, and is in generally good shape. I've cleaned the MAF sensor and throttle body and unhooked the battery for 30min+ to clear the computer.

It has never thrown any codes or lights, and generally runs really well. It seems different than some of the other threads I've seen on this. Usually there are CELs or codes to check out. Any ideas on what else to try?

The blue text is normal, the RPMs will be higher until the engine reaches normal operating temperature and then drops a hundred+ RPMs, the red text is normal when the AC compressor is cycling, either AC is on or defrost is on, RPMs increase when AC compressor engages.

 

[URBUGGED]

So only after the engine is fully warmed up, the idle on my v8 drops to around 500 RPMs when I'm in drive with my foot on the brake (at a stop light). It doesn't happen when the engine is cold. It also kind of "cycles" in and out of it. The computer will kind of "click" and the idle will return to normal ~750 RPMs. Then after a few seconds, it'll drop again to 500. (See the video)https://youtu.be/nOg8D-GQ58s

The 4runner has 115,000 miles on it, and is in generally good shape. I've cleaned the MAF sensor and throttle body and unhooked the battery for 30min+ to clear the computer.

It has never thrown any codes or lights, and generally runs really well. It seems different than some of the other threads I've seen on this. Usually there are CELs or codes to check out. Any ideas on what else to try?

Hi. This situation sounds very familiar to me when I owned my 2002 Camry. I know they are completely different engines but I just want to say there was a multitude of issues which could have caused that. I was able to narrow it down after several months when the engine idled so low it choked and shut down. One of the piston rings broke. You guys think that could be a possible problem lightemup has?

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[UrbanRunner651]

My 08 v6 just started doing the same thing. AC on or not, it didn't do it for the first 2+ years of ownership. Idle is more jumpy than consistent in the low ranges . I haven't dug into it yet but I would check you vac lines and air control valve. Had a similar issue in another vehicle and replacing the vac lines did the trick

 

[lightemup67]

My 08 v6 just started doing the same thing. AC on or not, it didn't do it for the first 2+ years of ownership. Idle is more jumpy than consistent in the low ranges . I haven't dug into it yet but I would check you vac lines and air control valve. Had a similar issue in another vehicle and replacing the vac lines did the trick

Do the 4th Gens have idle air control valves? I thought it just uses MAF sensor (which I already cleaned and it looks amazingly clean).

Where is the idle air control valve located on the engine? Is is cleanable? or just replace.

 

[lightemup67]

The blue text is normal, the RPMs will be higher until the engine reaches normal operating temperature and then drops a hundred+ RPMs, the red text is normal when the AC compressor is cycling, either AC is on or defrost is on, RPMs increase when AC compressor engages.

Blue text is definitely not normal. I've owned this 4runner for about 6 years and it consistently idled at 750 RPMs in gear with my foot on the brake at stop lights. 500 RPMs is too low and vibrates the whole car.

I definitely agree that RPMs increase when the AC cycles on, but its usually a jump from 750 to like 900, not 500 to 600 as mine does currently.

The idle is definitely low on the car all the sudden.

 

[DZNUTS]

The rpm in my v8 4Runner is 500rpm and 750rpm with the compressor on


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[lightemup67]

The rpm in my v8 4Runner is 500rpm and 750rpm with the compressor on


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Does it vibrate the truck? If I come to a stop, the idle will dip low, recover to ~500rpms, and you can feel the vibration throughout the truck. With a little gas, it will smooth out at 750rpms. While its warming up it sits exactly at 750rpms, with no vibration.

 

[AuSeeker]

Blue text is definitely not normal. I've owned this 4runner for about 6 years and it consistently idled at 750 RPMs in gear with my foot on the brake at stop lights. 500 RPMs is too low and vibrates the whole car.

I definitely agree that RPMs increase when the AC cycles on, but its usually a jump from 750 to like 900, not 500 to 600 as mine does currently.

The idle is definitely low on the car all the sudden.

It's normal for my T4R, no vibrations either.

That being said your idle/throttle control sensor maybe going bad.

 

[lightemup67]

It's normal for my T4R, no vibrations either.

That being said your idle/throttle control sensor maybe going bad.

Hm so maybe I should be checking motor and trans mounts. Although I believe 500 rpms is low, maybe the vibration is the problem. If it just sat at 500 at stop lights and didn’t vibrate the truck I’d be fine.

 

[DZNUTS]

Does it vibrate the truck? If I come to a stop, the idle will dip low, recover to ~500rpms, and you can feel the vibration throughout the truck. With a little gas, it will smooth out at 750rpms. While its warming up it sits exactly at 750rpms, with no vibration.

My idle does not cause any vibrations at all. Do you know how the check engine mounts?

First chock the wheels. Then, with the car in gear, hold the brakes and slowly bring up the engine RPMs and see if there is excessive engine movement. Also do a visual inspection of the rubber part of the engine mounts.


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[lightemup67]

Yeah, motor mounts look okay and there isn't excessive movement from the engine when revving it up. Have to look into the trans mount and exhaust hangars and stuff next. Thanks for the help!

 

[lightemup67]

Ended up doing spark plugs (stock ones from the dealer), and cleaned the MAF and TB again. Helped out the idle a tiny bit.

Finally got the wife to help me out and hold the truck in gear up on the ramps, while I got underneath. I noticed a broken exhaust hanger causing the exhaust to contact the trans mount/ cross member. Weird that it only really happens in gear, or maybe the decreased idle vibrated it just right to feel it in the cabin.

I'm going to have that hanger welded up, and hopefully that cures it!

 

[UrbanRunner651]

Yeah you are right its the electric MAF/TB my mistake.