Help me troubleshoot. Just bought an 01 Screw 5.4, 138,000 miles. Runs perfect with no miss. In OD running 60 or better its OK. If you fall below that and ease into the gas it will stumble. You can push the throttle down and make it downshift and its fine. Also with OD off it has no problems and runs strong. Engine or Tranny?

 

misfire or fuel system problem.

 

Runs like a scalded dog till it kicks into OD. Seems like it won't kick down right or it wants to be goin 60 or 70 in OD. If speed drops to 55 it lugs in OD. This truck will hit 60 a lot faster than my 07. Think somebody left a tune in it?

 

Low grade misfire. Happens usually after the shift into OD about 45-50 mph when driven normally. Does that sound like it?

That's a coil.

 

Sounds like it. How to find which one? Idles perfect. No codes. Checked with scan tool this evening. Replace em all? and find the culprit.

 

do you have service records on the vehicle?

if not, probably not a bad idea to change plugs and coils anyway. if the truck was serviced properly its about time anyway. if the truck was not serviced properly then its time.

the truck may run perfectly, but under load things sometimes don't operate as they should, especially if the parts are worn.

 

Yea those are b^tch to find. You have to take it in so they can Mode 6 it / look at cylinder history.

As cheap as coils are, you can replace them all and do the work yourself for what it cost at the dealership to find and replace one.

But the first thing you want to do is eliminate the possibility that you may have a fuel problem. It's possible, but more likely a coil with your symptoms.

 

Don't know the service history. Gonna get my dealer to run VIN and see how much info they might have. But I doubt they will have anything after warranty expired. So DG508's right? What plugs? Will get them on order from Ebay. What to check with fuel system while I wait for tune up besides filter? Should I do that motor vac service before the tune up?

 

Yea, 508's from Global or Uneek.

Motorcraft Plugs. - On the internet. you can get a good deal at Rock Auto, but allot of times you can find them locally cheaper.

Replace fuel filter , then check pressure at the rail, then regulator/w/applied vac. - If you have a Mighty Vac tool that is, - their cheap.

I would get the Motor-vac done first. It probably doesn't matter, but there will be foreign cleaners run thru motor that the plugs will get a taste of.

 

Great. Found most thru search but just wanted to be sure.Thanks a bushel.

 

No problem - Good Luck

 

If you're still on I was thinking about changing the tranny fluid and filter with Amsoil. If its never been changed would it clean it out too much?

 

You have a missing condition due to a bad coil with shorted turns.
It's a lengthy explanation to tell you why.
Either replace all and hope one of the new ones is not faulty or have a stress test done at a dealer shop to pick out which one it is.
It won't set any code to tell you which cylinder it is.

 

Yeah I just ordered the COP's. Can't find Motorcraft Plugs yet tho. Just Autolite. Part # might help. I'm sure it needs the tune up. If I get a bad 1 I'll do the test.

 

Yea Bluegrass is right, I don't know what's involved in the stress test tho.

Still it costs either way. I'll look up the plugs at Rock Auto. Hang on.

MOTORCRAFT Part # SP479 {#AGSF22WM, AGSF22WMF4}

Their 3 bucks apiece for the 01. "SP479" Is the numbers you want.