My 94 f150 is giving me a bit of hassel. it was skipping when traveling at a constant speed. i replace plugs, wires, cap and rotor, coil. seemed to cure the skip at constant speed for a while but now its skipping at idle, especially when at a stop sign with the transmission in gear.(auto) I checked the timing with a light( unplugged the spout short bar)#1 plug wire. . The timing mark was not even visible on the scale. Funny thing is, when i put the timing light inductor on # 4 spark plug wire, the timing mark is just about perfect!? I know its a skip because you can visibly see it with the timing light on the wires. any ideas where to go from here?

 

Which timing marks were you looking at? Ignore the ones cast into the timing cover. There's a small metal sector at 9:00 that is the correct timing reference. Also the notch in the damper pulley is not the timing mark. There are a pair of very faint lines marked 0° and 10° on the damper pulley. You need to highlight those with a paint stick and use them in conjunction with the sector.

Have you pulled your plugs and looked at them? If one of them is not firing cleanly, it will be obvious which one. Run a wet/dry compression test on all cylinders to rule out a mechanical problem.

 

I found the sector and the mark on the dampner, it only had one on it. hooked up the timing light, pulled the spout short bar and the mark appeared right in the large notch on the sector. now im not sure if thats where the 10 degrees before top dead center is? if you look at the sector from right to left there are a number of small notches, then the large notch, followed by some more small notches, and then a large protruding circle which i assume is used for something? One other thing i noticed is that when i felt it skip, the timing mark would appear way to the left of the scale. so now i have replaced plugs, wires , cap and rotor, ignition coil, ignition modual(fender mounted). I was wondering if the stator(pip) in the distributer could be causing it to do this? thanks so much for the assistance! my repair manual is sorrily lacking in the right imformation!

 

If you have only one mark on the damper, it is 0° BUT check carefully, there should be two marks. Bump the timing mark down to 6:00 and slide underneath and look carefully. you do not want to use the wrong mark.

The marks on the sector are confusing if you cannot read the numbers. The "points" are in 4° increments. The first one is 14° BTDC, the next is 10° which is the one to which you set the timing, then 6°, then 2°. 0° is at the bottom of the tooth followed by 2° ATDC and 6° ATDC.

You can usually bump the timing by 2-4° over the 10 ° BTDC stock setting

 

there are at least ten teeth( moving from left to right) on the scale before the large notch and 4-5 after the notch. im assuming the large notch is tdc. yes its very rusty and hard to see, and its under all the accessory drives(alt. emissions pump, etc.if i do find another line, it would be the 10 degree line? would i place the first in tdc? or the second?

 

As you describe it, the large notch should be TDC. There should be a faint marking next to the line on the damper indicating whether it is 10° or 0°.

If you cannot see anything assume it's 0° and set the timing at the 10° mark on the sector if you can figure it out. I have a dial-back timing light so I just use the zero marks and dial the advance into the light. Much easier than trying to read corroded numbers off a scale.

 

If the timing is jumping around, you could have worn distributor shaft bushings/bearings.

 

... or a worn/damaged drive gear

 

Only one mark on the dampner. did find out through a friend that the large notch is the 10 degrees btdc. the large circular protrusion on the scale is tdc. anyway, its right on. still got the miss and looking for more clues! how much play should there be in the distributer shaft? Im starting to wonder if another sensor( map, egr, etc) could be causing the computer to miscalculate the timing advance etc. only thing i havnt changed is the actual distributer or the pip sensor.

 

Figured out the problem, decided to do a resistance check on the new plugs. # 3 was real fishy on the multimeter, replaced it and runnin like a champ!Thanks for all the help!