Hey guys I currently just purchased a 2006 f150 with a 4.2. The problem is I have a rough idle/vibration when in drive at a light. When I got the truck first thing I did was a tune up, fuel filter, cleaned throttle body, cleaned MAF and fixed some oil leaks. I also have no codes. Can anyone give me some ideas on where I should look next?

 

Please be more specific with "tuneup". Off idle, does it run smooth and have normal power? How many miles are on it?

 

plugs and wires. It seems to run fine when driving its just sitting in drive it has a vibration and sometimes the vibration seems to lobe. Its worse with the A/C on. 160k miles

 

Did the problem start immediately after the "tuneup"?

Over the years a few 4.2L owners have had the keyway on the harmonic balancer wear enough that the balancer slips and it throws off the valve timing. May be worth looking at.

 

No it had the vibration when I purchased it.

 

Check the compression just to make sure the engine is okay.

 

I did a relative compression on the IDS at Ford and the worst was down 5% I was planning on doing a full compression test but the worst being 5% on something with 160k on it isn't that bad. I'll probably do a full compression test soon but the way it runs when driving doesn't doesn't indicate a half dead hole or anything like that. Just at idle when in gear with A/C on

 

I would pull the coil pack, clean it up and inspect it carefully for cracks and carbon tracks.

Pull the serpentine belt and see if the vibration goes away.

Note that the 4.2 is not really a smooth engine, it's a 90 degree V6 which is not naturally balanced, that's why it has a balance shaft.

 

glc is correct. The 4.2l v6 is what I'd call a "hand shaker" if you had a standard shift. It's not the smoothest engine out there, but it does it's job.

What you'll want to look, smell, and listen for is detonation/misfiring under load, any unburnt fuel odors, burning coolant/oil odors, low idle/erratic idle, jerking while accelerating, squeaking from the harmonic balancer, and check engine lights.

If it you don't have any of those, then chances are the engine is running OK.

 

Its an automatic. I know normal vibration is ok but it is erratic it lobes up and down sometimes to the point of rattling the entire truck. No coolant leak no fuel smell. Finally fixed all the oil leaks. No misfire or detonation. Also my fuel economy is horrible i thought it being a v6 i would do better than the 10 I'm getting

 

That sounds like a vacuum leak. I'd go over all vacuum lines with an UNLIT propane torch and see if there is any change in idle.

 

No lean codes and running 18 hg in vacuum if there is a leak its very small

 

Did you look at the keyway on the harmonic balancer?

 

No I haven't pulled it off yet. I ordered a new one cause I might as well replace it while I have it off

 

Ok started throwing parts at it for the normal issues these trucks have. New harmonic balancer, new motorcraft coil, lower intake manifold gaskets and cleaned all the crap out of thin intake including runners while it was off. Did a off car injector cleaning as well. Its all back together and seems the vibration got alot better. Now it seems like I lost power with no miss or stumble it just doesnt want to seem to get out of its own way. I decided to invest into forscan since i own 2 f150s. i took a screensot of a few pids. The fuel trims seem low to me can anyone give me insite on that