My 04 Fx4 had an idle prob and wasn't throwing any codes...was shaking excessively.....I cleaned MAF, IAC....changed plugs, pcv and fuel fliter ....tightened intake manifold and throttle body to no avail. I was stumped so I took it to Ford today............................................. ..it was the Harmonic Crank balancer....it was broke. $578 later and she runs like she was brand new.
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Rough Idle Fixed
- Thread starter fitn217
- Start date
firefighter525
Well-Known Member
Can you explain what it was doing a little better? Shaking excessivly when? All the time or certain rpms?
I ask because I recently swapped another 4.0 in my truck and it has a wierd vibration. It idles very smooth and only vibrates @ 1500 rpm. Also, it will vibrate when in gear and just starting to move around the same rpm. The vibration won't rattle your teeth or anything, but it is noticable and can be felt throughout the whole truck. Above 1500 rpm, it smooths out and is not present.
I ask because I recently swapped another 4.0 in my truck and it has a wierd vibration. It idles very smooth and only vibrates @ 1500 rpm. Also, it will vibrate when in gear and just starting to move around the same rpm. The vibration won't rattle your teeth or anything, but it is noticable and can be felt throughout the whole truck. Above 1500 rpm, it smooths out and is not present.
My 4.0 excessively shook at idle....specifically low idle...800 rpms. On high idle it vibrated as well but not as noticeable. Going through the gears ...or when driving at all ....at all rpms.....she felt normal.
turbotaguy
Member
- Joined
- Nov 28, 2009
- Messages
- 23
- Transmission
- Automatic
fitn217 - I just bought an 04 Ranger with the 4.0 and it has exactly the same rough idle you describe (no codes, idle only, smooths out through the gears). I tried a bunch of things just as you did but no help.
How did they diagnose the harmonic balancer? Did you get the part back? What did it look like, just a crack or a chunk missing? I'd hate to replace something like that just to have it NOT be the issue.
How did they diagnose the harmonic balancer? Did you get the part back? What did it look like, just a crack or a chunk missing? I'd hate to replace something like that just to have it NOT be the issue.
turbotaguy
Member
- Joined
- Nov 28, 2009
- Messages
- 23
- Transmission
- Automatic
I decided to take mine to the dealer too so I didn't go through replacing a bunch of parts and guessing what the issue was. They diagnosed a bad harmonic balancer too. $400 later it runs like a champ and idles perfect.
I've never heard of a failed harmonic balancer. Must have been a crap design.
I've never heard of a failed harmonic balancer. Must have been a crap design.
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