Engine shaking at idle

[stang1986gt]

I have an 05 Explorer, 90,000 miles, 4.0 engine. The engine shakes at idle and I can't figure it out. Not missing when you listen at the rear of the truck, but the engine is shaking noticeably. Smooths out when you accelerate. I have changed the plugs and wires (initially had a code of #6 misfire, but I now have no codes after clearing the computer).

I would think that if it was the balancer, it would get worse with acceleration, correct? What could it be? The idle itself seems to be ok as the RPMS aren't jumping up and down any at all. It's hard to tell if it's just idling really rough and causing the engine to shake or not. I haven't tried cleaning the IAC yet and plan to do so soon. Any other suggestions?

 

[jmorristn]

take off the rubber intake hose at the throttle valve and clean it with spray cleaner and a rag. You will need to hold it open with your hand and clean it. mine would idle real low and I cleaned the throttle valve and now it's fine. throttle valve is operated by the electric motor and wireless throttle.

 

[Fox Fader]

Nature of the beast, you ain't fixing that.

jmorristn, you mean a "cableless" throttle... Because it is drive-by-wire, which I don't like the lag and it dosen't have to be that much of a lag. I used to sell Mazda's and their DBW was virtualy lag free. This is like driving a Benz.
lil rant there.

 

[jmorristn]

yep drive by wire, the lag time with mine improved after i cleaned it but it still has some. I agree it should be much better. I used SeaFoam spray cleaner and an old sock to clean it and that really helped. Mine was giving the P0506 low idle code. Now when it starts it idles up higher and then will steady out, before it would drop back down to about 450 and surge up an down. I had already put new plugs and a throttle position sensor on before cleaning and new fuel filter. if you do the fuel filter get the metal line tool, no plastic ones.

 

[shadowless127]

Fuel Filter, and possible a dirty IAC.

 

[jrford]

i would assume you checked for Vacume leaks? Cracked vacum line? one poster a while back found one of the hoses with a hole in it. It was also very hard to find and at first it was over looked.

 

[Hitchhikingmike]

I would take off your IAC (idle are control) unit and visually inspect it for carbon. Even after I sprayed out my valve body with carb cleaner there was still lots of Carbon jammed up in the IAC that I could only get out with a pic. After that my ex started and idled better.

The IAC is shiny aluminum and is located on top of the valve body.

 

[stang1986gt]

Thanks for all the responses. I did check for vacuum leaks with starting fluid and visual inspection and found nothing. I wish I could explain the problem better, as it is running extremely smooth when you listen at the tail pipe.

I have not cleaned the throttle body or the IAC yet, so I will try that this weekend and report back.

 

[Fox Fader]

All these 4.0's, 4.6's, 5.0's shake a little at idle, that's just the way they are, if it's not shaking the truck then you are ok.

 

[stang1986gt]

No, it's shaking the truck. I always did feel vibration from idle, as is normal. But it's shaking the truck like it has a dead miss on one cylinder, but when you listen through the tail pipe, it is smooth.

I've pulled one plug wire off at a time and nothing changes, so it's not a miss. At the beginning of this I had a code of misfire on #6, but the plugs were worn down and I replaced them. Shaking is still there. I cleared the computer by pulling the battery cable over night (this was about a month ago) and I now have no codes that come up.

 

[Fox Fader]

Well if it's shaking like that then there is a problem. Clean the IAC first. Stock air box right? then air flow sensor should be clean, check it but be VERY careful with it.

 

[stang1986gt]

It has a new air filter in it, and I cleaned the MAF sensor as well (yes, carefully...lol). It was a little dirty, but not too bad.

If the IAC was dirty and not operating correctly, wouldn't it sound rough through the exhaust as well? I'm going to clean it anyway as has been recommended because I know it's never been cleaned.

 

[Fox Fader]

That I don't know, I've never listened to the exhaust

 

[NC FX4 Scab]

Hey guys...new member here, although I've been a member at f150online for years...

the 04-05 4.0 Explorers don't have an IAC...I ran into this problem a few weeks ago with wife's Ex. Had the same problems with rough idle, idle rpms dropping, and even stalling as the problem got worse. The PCM finally threw a code last week, after the dealership had looked at it and couldn't find anything. If there are no vacuum leaks, and the obvious stuff has been changed/checked, then one of your O2 sensors is going bad. Mine dragged on for a few months, progressively getting worse, with no trouble code, until last week. Installed 4 new O2 sensors this week, and it's running like a champ again...

Hope this helps...it was driving me crazy for weeks!

 

[Fox Fader]

I had the opposite happen with an S-10 before. It was idling too high. I worked at the dealer then, we tried PCM flash and checked everything we could think of. I bought new O2's from oxygensensors.com and that was the fix.

 

[NOPSTNS]

Did you get the latest PCM flash for the 4.0? There was one brought out at the end of 2008. This fixed some idling issues on my truck. However, where yours sound worse at idle, it may not hurt to do it but probably won't solve the issue.

 

[alexk]

I have roughly 95000 on mine. It does the same thing and on mine its the ignition coils. I eventually will need all 8 replaced but Im just getting them done as they go (my mechanic only charged me $10 to put them in so its not like I would save by doing them all at once.) Check for them. Right now my service engine light is off but it was on, on sunday. Took it to my mechanic he hooked it up to his reader hit the gas and it went off. So now I have no check engine light but a vibration like you.

 

[tonydp]

did you ever figure this out? My 02 does the same thing. The idle doesn't skip a beat but there is a good shake going one. It drives great but just when it's not rolling the thing shakes. Maybe the idle is to low? Once again, it doesn't surge or search for idle, it's dead on.

 

[jmorristn]

i cleaned the throttle valve.

 

[dvalot03]

I just took mine into the shop for this same problem. It has been doing this for about 2 years now, gas mileage 18mpg highway, i have changed the plugs wires fuel filter, cleaned the TB, nothing seemed to help. Well they smoked tested it and here to find out the intake manifold gasket and the O rings on all injectors are bad. haven't fixed it yet, just put $300 into a wheel bearing so the other stuff has to wait.