Trying to help a buddy diagnose a "skip" in his '98 F-150 4x4 with the 4.6/automatic (78k miles). It is very consistent on when it does this. It happens under very light load when in Overdrive, such as cruising along on gently rolling hills or up a very slight grade. If more throttle is applied, it will kick into 3rd and the "skip" goes away. So far we have changed the fuel filter and the plugs, but the problem is still there. There is no CHECK ENGINE light on, and when it "skips" the tach does not bobble at all. Has anyone got any ideas on where to go from here? Is this a common issue with the 4.6? TIA for any help!

 

I have the same problem on my 01 Expy with the 4.6l. I have not found the source of the problem yet either. I have also changed plugs, fuel filter, throttle postion sensor and checked the resistance on the coils. I am going to try and replace the boots on the coils before I purchase 8 new coils. I have also cleaned the throttle body and the egr ports which were almost clogged with carbon. I wish I could find the answer too. Its getting real annoying.
Btw: 78K on the engine.
And changed fluid and filter and added Lucas Trans Fix to it also.

 

are you sure its not a trans/tc problem. when was the last time the trans was serviced?

 

I had the same problem with my 2001 Expy 4.6. It was a bad coil pack. Buy 1 new coil pack from Autozone. Cost about $47.00. Replace it one at a time then test drive the vehicle. Keep swapping the pack until you find the bad one. It's a very easy fix. Just takes time. I guarantee it will fix it.

 

I have had the same problem in the past. I assure you if you have not changed your spark plugs, that is your problem. Allow lots of time, back 2 plugs are pain in the rear to replace. Also use plenty of dielectric grease. Water tends to foul out this engine. Changing plug wires may aslo be a good idea. This is a job you only want to do once. trust me!

 

Already changed the plugs, and you are right... Don't want to do that any more often than absolutely needed!! Problem is still there, though, so I guess we are leaning toward plug wires and/or coil pack? There are only two coil packs, so buying one and trying it out would be a real simple guess and check game. Trouble is, you waste the $50 if neither one turns up bad... Is there any way to test them on a bench?

As for the trans, it was serviced at 25k, but is probably due again. I don't think that's the problem, but it's sure worth a shot and it never hurts to service the tranny anyways.

 

I had the same problem a while back.

After the transmission was serviced, my 'skip' went away.

I would also like to point out that in my experience, the transmission skip and the skip caused by a plug going bad are VERY similar and hard to tell apart.

I had a plug go bad this past weekend and at first I thought it was the transmission acting up.

 

Plug wires - you don't have the Coil over Plug System (COPS) - others call it direct ignition.

Mine did the same thing, but got worse and worse. Changed the plugs, got worse still. CE light said misfire on #3 & #4, changed #3 wire and now runs slicker than owl poop. Changed the rest of the wires to prevent a recurrance.

If that doesn't fix it, then the next step is the coil module(s).

Also, change the tranny fluid & filter (including the T/C) - it's due, and fairly inexpensive - good insurance.

Good Luck,

Jamie D.

 

hey, I also have a 98f150,4.6 but 5 spd and I have had the same problem for a couple of weeks now and my check engine light finally came on and showed up as a misfire on cyl 8.

when i pulled this plug i found what i can only describe as a carbon track on the top of the plug from one end to the other (top to bottom)porcelain. I cleaned it off and replaced it.

Then I found a post that said that if any harness wires are touching the a/c condenser it will cause a simaler problem, well idont know what one did it but i woul move away those wires because it seems to work for a lot of people