I have a 1997 F150 with 4.6 litre V8 and 96k miles on it. I recently took it into dealer after my check engine light came on. They told me spark plug wires and spark plugs needed to be replaced and recommended cleaning injectors as well.

I replaced the spark plugs and wires myself and then brought it back to them to do the maintenance on the injectors. I just got it back last Thursday (2/27/03) and it still misses(but not always) it will act up when i first start up in morning and when i come to a stoplight (but again, not always) any idea what this could be?

Thanks,
Fred

p.s. they told me orignailly that the check engine light came on becasue the number 8 plug and wire were rusted and recommended replacing them all since they would be in there.....

the check engine light is off now too



anyone have any other ideas? see below




hapynzap: You say you had a check engine light. What were the codes? Do you still have a check engine light?


JMC: Check your plugs and wires. If the wires are not properly seated they may cause a miss. If the plug are not tightened they may also miss or allow the fuel mix to blow past the seal. Dielectric grease on the contacts helps and never seize on the plugs.

Regards
JMC

 

Check to see if any of your coolant hoses are leaking by cylinder #4. Several members have had this problem with an intermitten miss because the spark plug gets immersed in coolant. A lot of times the heater hose just needs new clamps or to be tightened. But it goes over the #4 plug and causes the problem

Brian

 

I have a 97 F-150 with 91,000 miles that had the same problem. Although I changed the plugs and wires around 75,000. Turns out it was the number 8 plug. The wire slipped off a hair makeing it miss in the mornings when it was cold and when it rained. It had been that way for so long it ruined the plug and wire due to carbon build up. Make sure your new plug wire is still snug.

 

Hi
Make sure you put the wires on correctly. I have seen more than once a couple crossed up and things seem fine. Also, the coil packs are a different animal from the single coil of yesteryear. A bad wire or plug can cause the coil for that cylinder to work too hard, poss. damaging it. There are ways to check this out. Most books have a procedure if you have a DVOM( volt meter) Injector cleaning is a scam. Almost ALL modern injectors are coated and some manufactures actually recommend NOT cleaning them for fear of damaging the coating. Hope this helps.

 

I too HAD a rough idle at stop lights.(102,000) Two weeks ago I changed my front two o2 sensors. No more rough idle.

Mike

 

Do you wash the truck often? Do you wash under the hood? Do you go off-road alot? What I'm getting at is if there is water getting sprayed or splashed under the hood it gets in along the boot on the plugwire and causes a "short" at the plug. Alot like the coolant leak described earlier.