99 F-150 Lariat Supercab 4X4, 5.4L

Sometimes when accelerating, the truck shakes, but when I let off the accelerator, it stops. It only does this on occasion, and I have been unable to determine a set of circumstances under which it happens.

Any thoughts about causes and fixes?

Also, the "silver" is gone from the side mirrors (heated, signal mirrors). I have seen this on other trucks; I assume it is common with these mirrors.

Can the lenses alone be replaced, or will I have to replace the whole assembly? If you have had this problem, did you replace with heated, signal mirrors, or did you use other kinds of mirrors?

Thanks for the replies!

 

Hi and welcome to FTE

Does the shaking feel like it's coming from the engine or elsewhere? If it's from the engine it could be a bad spark plug or COP (Coil On Plug).
How many miles on the plugs? Does the Check Engine light ever come on?
If it's not from the engine you may have a bad U-joint.
Usually a U-joint will do it consistently though.

I believe that you can get the mirror lenses separately from Ford.

 

Maybe a U joint going bad. Try accelerating from a stop while turning left.

I don't think the glass is available by itself. If it were mine, I'd remove the cover ( painted or chrome piece on the front). It's held on by 4 tabs. You tilt the glass and use a long thin flat head screw driver to pry the clips lose from inside the mirror, and after a few minutes of swearing at it, the cover pops off. I would then drill or cut a couple small holes where the cover was (careful not to hit any of the workings inside ), tape off the face and housing of the mirror and try spraying the backside with maybe some chrome paint, and if that works maybe top it off with either some clear coat or maybe even some undercoat type spray to protect it.

I've never tried this, and it's just a thought, but with the cost of replacing those mirrors, what have you got to lose.

 

Could always try rebalancing your tires? Sounds like if it quits after you stop accelerating, it is probably engine related though.

 

Thakns for the replies! The truck has 100,000 miles on it; I'm not sure how many miles the plugs and cils have. It may be time to change those.

My mechanic seems to think it may be vibration from the transmission. He described it fairly well, and it only happens when the truck has warmed up fully.

I thought it might be a u-joint, but it seemed that would continue to shake even after letting off the accelerator.

It goes in Friday. We'll see.

Thanks, again!

 

Check on Muth Signal mirrors. I'm pretty sure they make what you are looking for. I've heard from others these guys are actually the original makers for the F150. They had some mirror problems from the beginning and replaced some. So who knows, maybe call them up direct and they might give you a deal.

But yes, you can replace just the glass. I had my Screw upgraded from standard mirrors to signal mirrors.

 

My 97 5.4 had an engine shake only in overdrive while lugging slightly. It would go away after letting of but come back at the same rpm range. I chased the problem, thought trans, torque converter, u-joints, had it scaned with no results. Turned out to be an 8$ boot between coil and plug that had a verry small crack in it. If this sounds like your problem dont over looke them like I did

 

Usually vibrations caused by the transmission are really rare.
I've seen transmissions replaced and rebuilt because of misfires.
I've also seen tune ups done because of transmission problems though too. A common one is what feels like a misfire but is actually the torque converter clutch shuddering as it locks and unlocks. Usually you'll feel that at a fairly steady throttle at roughly 40 mph and then accelerating slightly.

 

Mechanic said the codes indicated the truck was running extremely lean. Changing fuel filter and maybe carb clean. We'll see what happens.

I need to have the coils checked and plugs and wires replaced sometime soon.

Thanks for the info on Muth mirrors!