Rough Idle..... No CEL/Wrench

[batesfusion]

I read and read posts on here and got a bunch of great suggestions. Tried them all.... None worked lol

06 Explorer 4.0.
At 650 RPM it idles rough. You can feel the whole vehicle shake lightly and you can see the engine shaking too....
But when you drive it, it runs perfectly fine above idle.....

No Check engine light or wrench has came on. Only showed a code for the IAT being outta range....

So far Ive done....
Cleaned throttle body, it was filthy
Replaced the mass air after the code reader said that the IAT sensor was showing high input
Serviced air filter
Checked for vacuum leaks
Checked all plugs and plug wires
Tried different gas
Reset the computer multiple times

Any suggestions would be great

 

[Flag Gibby]

The 4.0 idles a little rough at 650 RPM, that's just the way all the ones I have come across are. I was never able to fully get mine to idle smoothly, but changing to a fine wire NGK double platinum plug did help smooth it out some. I think that it has to do with the waste spark setup on them, but I could be completely wrong on that.

 

[batesfusion]

I understand the rough idle part but I mean it just started noticeably shaking. No explorer would idle like this and be considered normal

 

[GFish]

Rough Idle

My 06 EB 4.0 with 150,000 miles idles so smoothly and quietly you can't tell if it is running while sitting inside.

 

[batesfusion]

My 06 EB 4.0 with 150,000 miles idles so smoothly and quietly you can't tell if it is running while sitting inside.

And that's how mine was till recently...

Ive read about possible harmonic balancer problems... Any insight?

 

[batesfusion]

Bump this up

 

[Flag Gibby]

If you say the wires and plugs are good then how many miles on the vehicle? The only other things I can think that might make a difference at idle would be the coil pack and maybe the O2 sensors, but that depends on how many miles on the engine.

 

[batesfusion]

112,000....

All the plugs looked good. The wires have 0 corrosion in either end. Checked the plug to the coil pack, that's all good.
I guess I just thought if it was anything to do with spark it would be noticeable even with the slightest bit of throttle, but this completely disappears about 1000 rpm...

 

[Rcflyer330]

here is what the Haynes repair manual for 2002 to 2010 ford explorers for "engine 'lopes' while idling or idles erratically."

1. vacuum leaks
2. leaking EGR valve or plugged PCV valve
3. air filter clogged
4. fuel pump not delivering sufficient fuel
5. leaking head gasket
6. timing chain(s) worn
7. camshaft lobes worn
8. valves burned or otherwise leaking
9. ignition system not operating properly
10. fuel injection or engine control systems malfunction

i am not a mechanic but we know its not number 3 for sure

 

[Flag Gibby]

112,000.... QUOTE]

If you have 112,000 on the original plugs, wires, and coil pack it is time to replace them. The shielding on the wires/coil pack break down over time allowing more and more of the voltage to leak out resulting in a less efficient spark that can be noticeable at idle. Also, if the plugs are the OEM platinums, they are only good for 100k miles IIRC and they may look good but like the wires they just wear out internally resulting in less voltage making it to the electrode tips.

Also, per the previous post, the PCV valve is a maintenance item that should be replaced at 100k or 125k miles (I don't recall exactly which one).

 

[batesfusion]

112,000.... QUOTE]

If you have 112,000 on the original plugs, wires, and coil pack it is time to replace them. The shielding on the wires/coil pack break down over time allowing more and more of the voltage to leak out resulting in a less efficient spark that can be noticeable at idle. Also, if the plugs are the OEM platinums, they are only good for 100k miles IIRC and they may look good but like the wires they just wear out internally resulting in less voltage making it to the electrode tips.

Also, per the previous post, the PCV valve is a maintenance item that should be replaced at 100k or 125k miles (I don't recall exactly which one).

Im at my wits end i think lol....

Replaced the plugs, coil pack, wires, fuel filter, pcv valve. Ran sea foam through the system and guess what...

STILL NO CHANGE.... FML

There is a lot of black soot around the back of the engine near the pcv valve. Possible egr problems?

Still no codes showing either by the way

 

[Flag Gibby]

With the car running try to track down where it is coming from. It could be an EGR leak (see item 2 on post 9). Also, sea foam in the engine can blow oil, etc. out of really unusual areas too, so it may be nothing if you noticed it after you did the whole sea foam thing.

 

[batesfusion]

With the car running try to track down where it is coming from. It could be an EGR leak (see item 2 on post 9). Also, sea foam in the engine can blow oil, etc. out of really unusual areas too, so it may be nothing if you noticed it after you did the whole sea foam thing.

Sea foam in the gas. Not sure I coukd ever talk myself into running it through the oil

 

[Markaprice73]

I see no mention of you doing a the throttle body relearn procedure. Very important after any repair. Also, was your new MAF a n OEM Motorcraft?

http://youtube.com/watch?v=hZAsoqmqhdM

 

[batesfusion]

I see no mention of you doing a the throttle body relearn procedure. Very important after any repair. Also, was your new MAF a n OEM Motorcraft?

http://youtube.com/watch?v=hZAsoqmqhdM

Aftermarket maf but it cleared the code that the factory one was showing.

 

[Markaprice73]

We'll assume the MAF is good to go. Definitely do the steps in the video. Especially the relearned idle values(2:25 in the video) The procedure is in your owners manual aswell.

 

[batesfusion]

We'll assume the MAF is good to go. Definitely do the steps in the video. Especially the relearned idle values(2:25 in the video) The procedure is in your owners manual aswell.

Check. Got it done. Still got the vibration. Wish this thing would show some more codes!
The harmonic balancer appears to be in good condition though.

 

[Markaprice73]

Hmm. Hoped that would do the trick. Give it a day or two of driving though. Maybe check the egr system next.

 

[batesfusion]

Here's the tach after the idle reset... Not sure if you can here the miss in the video or not...

http://youtu.be/FyD0JqdBYfg

And one of the engine...

: http://youtu.be/WL35LOItCiU

 

[batesfusion]

If it means anything.. My gas mileage went up a little over 1 mpg on the highway after these parts lol... Still missing /shaking at idle up to roughly 1700 rpm