earnest13

It mainly does it when it's warming up, when the RPM's are at ~1K while coming back down to idle speed. It's more like a shimmy than a shake, like something is out of balance in the engine at that RPM but I know thats not the case(well I think I know) and it's driving me crazy!

I've replaced the plugs with new MC SP479's, replaced the COP's with new SMP/BWD's from Advance since they have a lifetime warranty, new MC fuel filter, replaced the fuel injectors with a known good set of MC CM5081's, cleaned MAF and TB, and checked the engine vacuum at idle (rock steady at 21 in vacuum).

I'm running out of ideals, nothing I've done so far has made any difference and I'm not sure what to check next.

Please help, all comments and recommendations are welcome.

Oh and the truck is an 03(made after 1/15/03) F150 FX4 Screw Lariat w/ 5.4L engine, 4R70W trans and 249K mi on the odometer.

Thanks,
Earnest

ibd2328

iTrader: (2)

Well I'd like to congratulate you on your truck being built on my birthday. Also you have my fathers name.

As far as your problem. I have no clue hopefully someone smart will chime in.

Z7What

The engine could show vacuum at 21, even with a vacuum leak!

Any codes?

Is it make this issues after reving and the RPMs fall back down? IAC? Did you gap the plugs, only other suggestion is try Motorcraft COPs maybe. Does it use oil, is coolant clean(possible head gasket)? Really hard to tell my man, wish I was of more help.

Wayne

w0lvez

If the Mounts are not damage you just need to Neutralize the Engine and Tranny mount. You need to lift the vehicle loosen all bolts holding the engine and tranny. Lower the vehicle move 3 feet forward and 3 feet Reverse. Lift it and tighten the all the bolts. Check if there is a bolt holding the exhaust pipe near the tranny support. Try loosening the bolt and tightening it.

earnest13

No codes, if there is a miss of some sort it's to faint for the computer to pick up. I have a code scan tool, wish I had a better one so I could see current fuel trims.

Yes if I rev the engine as the rpms fall back past the 1K mark the engine will shake a little, not as much once the engine is warmed up.

Yes plugs where gaped at 54 thou.

uses ~1/2 qt oil between 5K mi changes(M1 EP 5W-30)

coolant is clean, no leaks, no bubbles, nothing else I've noticed to make me thing a head gasket is leaking.

Changing to the new cops didn't really change anything, it had motorcraft cops on it. It does start faster and pick up speed better with the new cops but the engine shaking was not affected.

Thanks for your help.

earnest13

If all else fails I may just try this, if I had access to a lift I would go ahead and do it.

Thanks,
Earnest

jstockert

ibd, you are the most knowledgable 11 year I know. I know you meant the month and day but could not resist.