Help with F150 rough idle/hesitation/vibration

[hazmat]

2001 F150 sometimes has rough idle & hesitates under light acceleration, but if you mash the pedal it runs fine. The hesitation is accompianed by a vibration.


Of course the problem is intermittant. Dealer replaced Idle air control valve to the tune of $200. But it didn't solve the problem.

Please help.

I'm going to start another thread on computer code scanners.

 

[Bird]

</font><font color="blue" class="small">( I'm going to start another thread on computer code scanners )</font>

A couple of weeks ago, the "check engine" light came on on my 2001 Windstar. It was running just fine, but I took it to the dealer, they said they got a code indicating it had run a little rich at some time, but not now, so they supposedly checked the fuel pressure, etc., and found nothing wrong at all, so it only cost me $92.77 for them to check it out and find nothing wrong. /forums/images/graemlins/frown.gif But since it took them over 3 hours to do it, they did give me the oil and filter change free. /forums/images/graemlins/wink.gif /forums/images/graemlins/laugh.gif

 

[slowrev]

You can buy an engine code reader for about the same or less than having the dealer dump the codes one time. My vote is on plug wires or a coil pack. EGR...maybe...

 

[jpr62902]

I had a similar problem with my 2000 F150 (5.4L V-8). It was an injector that went bad. Not sure if this applies to you, since my truck went downhill real fast (as in over 2 days) before it would hardly even run. Good luck!

 

[Mark_in_NH]

I had a Very similar problem (no vibration) about 1.5 / 2 months ago with my 2000 F-150 4.6 V8 89,000 miles. The dealer replaced the plugs, which it was due for, and wound up replacing a coil pack to correct the problem.
Long gone are the days of just one coil. My truck has 8 cylinders, 8 plugs and 8 coil packs. /forums/images/graemlins/tongue.gif

 

[goodoleboy]

Easiest cheapest solution plug wires you can test those with a voltmeter.
Also "Check engine lights" can be read at autozones for free.

 

[Kubbruce]

I would tend to lean towards a coil pack myself. These can be ohm tested as well. There should be a test for both the primary and secondary side of the coil. I'm not that familiar with the set up so I don't know which wires you need to hook the ohm meter too. Don't just go with an OE spec, but also check all of them to see if you have one that is weaker then the others.

 

[Rowski]

How many miles on the truck?

 

[JimR]

Check the vacuum hoses also. A leaky hose would cause that same problem. A vacuum gauge will tell you if there is a problem related to air leaks or a bad intake valve. Depending on your mileage, I would then look at the spark plugs, wires and coils.

 

[hazmat]

Thanks for the tips guys.

57,000 miles on the truck. I assume it is still on it's first set of plugs (I bought it at 19,000 miles).

Per advice of another buddy, I cleaned the throttle body today - it was pretty sooted up. Is that normal??

I also bought a new fuel filter - but didn't know I needed a gizmo to get the fuel line un-hooked. /forums/images/graemlins/mad.gif I'll pick that up this week.

Regarding the coils & wires - I don't yet have a service manual. Anybody got the specs for testing those?

Thanks again.