hesitation, studers

[BIG GREEN FORD]

Help I have a 99 expy with 87,*** miles going around 45, 50 mph it hesitates if I stay in that range if iI go fast its normal or if I go slower.
-new fuel pump
-spark plugs motocraft 6000 miles ago
-fuel filter 400miles ago
-throttle cleaned 10000 miles ago
-Cylinder 7,8 new coils

 

[stamp11127]

Will it throw a code if you hold it in that range?

 

[BIG GREEN FORD]

Will it throw a code if you hold it in that range?

No just jurks the crap out of me. Also if i take overdrive off it won't do it as bad. You can badly feel it

 

[stamp11127]

Check the plug wires, coils and the dielectric grease. If you have a timing light, observe the firing on each cylinder throughout the rpm range.
It may help to watch the plug wires at night, if there is a problem you may be able to see it.

 

[BIG GREEN FORD]

Check the plug wires, coils and the dielectric grease. If you have a timing light, observe the firing on each cylinder throughout the rpm range.
It may help to watch the plug wires at night, if there is a problem you may be able to see it.

How does the timing light work? What does it tell me? Or in other worlds what is it suppose to say. Will get one tomorrow. Thanks again for the reply

 

[stamp11127]

Borrow / rent one from an autoparts store. The changes in engines today will make it a one time use tool since you only use it on plug wires.

It will flash every time the coil fires a spark plug. You move the pickup from one plug wire to the next observing how it flashes. Checking at idle, there should be a rhythm to the flashing on each cylinder. You will see if there is something wrong once you hook up. I cup my hand and point the gun at my hand to watch the flash.

I've had double flashes, no flashes and flashes that come and go. It is an older type tool that will only work with coil packs. Doesn't work with COPs.

 

[BIG GREEN FORD]

Borrow / rent one from an autoparts store. The changes in engines today will make it a one time use tool since you only use it on plug wires.

It will flash every time the coil fires a spark plug. You move the pickup from one plug wire to the next observing how it flashes. Checking at idle, there should be a rhythm to the flashing on each cylinder. You will see if there is something wrong once you hook up. I cup my hand and point the gun at my hand to watch the flash.

I've had double flashes, no flashes and flashes that come and go. It is an older type tool that will only work with coil packs. Doesn't work with COPs.

Okay I will let you know what happens. I'm going to run it in the dark see what happens. Thanks again. I had this proplom since i bought it

 

[stamp11127]

If any of the wires are arching you will see a small blue spark and hear a snapping sound. If you don't, check them with the timing light.

This may not find your problem but at least you will know whether or not it is spark related.

How old is the wire set?

 

[BIG GREEN FORD]

If any of the wires are arching you will see a small blue spark and hear a snapping sound. If you don't, check them with the timing light.

This may not find your problem but at least you will know whether or not it is spark related.

How old is the wire set?

Probably from factory besides the two new coils