ford f150

[Anonymous-0]

i have a ford truck 85 4.9 l have developed a miss after running 30 miles . like some thing electrical breaking down when it gets warm . intermittent miss.no vacuum leaks no fuel problem could this be the square coil warming and causing problem ?i know this is a tractor forum . but i know one of you have run in to this problem before. thanks for your help in advance .

 

[ericlb]

its a 1985? if so id be more likely to suspect a plug wire or a bad sparkplug there should be only 1 coil on a '85 model, if it was bad the whole engine would shut down, not just 1 cylinder, when was the last set of wires installed? if 85 was a mistype i dont know as i refuse to own newer cars, if i cant fix em, i dont own em lol

 

[ericlb]

forgot to add, if the wires are good, there is the electronic control module, although fords problems with those would have been fixed by 1985, and if bad, again the whole engine would shut down, then fire back up when cool, also check for a cracked distributor cap, look for a blue/black area where the voltage is jumping inside the cap

 

[wickedsix]

Have you pulled any codes?

 

[souNdguy]

ditto what the others said. I think I'd look at cap, plugs and wires first. a single cyl miss, once it starts, if it is constant can be found by pulling and replacing 1 wire at a time till you find a cyl that don't effect anything..

soundguy

 

[souNdguy]

ditto what the others said. I think I'd look at cap, plugs and wires first. a single cyl miss, once it starts, if it is constant can be found by pulling and replacing 1 wire at a time till you find a cyl that don't effect anything..

soundguy

 

[DanH01]

Chances are the other posters are right and the source of the miss is in the Dist, plug wires, or even a plug itself. I"ve got a 1989 F150 with a 4.9. It was old when I got it and had over 125000 miles on it. Ran ok but had a miss. Which didn't bother me so much as I thought it was a wire or plug. And I always change those when I buy an old vehicle. I went over it many times. Tuned it up, changed oil, filters, plugs and wires, and cap and rotor button. Ran better, got better gas mileage, more power but still had that miss.

Turns out it wasn"t a miss so much as it was a leak that sounded like a miss. The very last cold air injection tube that went into the #6 cylinder was broken and and leaking. It"s the one way in the back and hard to get to. It was kind of hard to tell cause it was still standing in place and muffling the sound and not allowing the head/motor to build up much pressure. I had some difficulty getting the tube out as it was heat welded to the head. I ended up just welding the end of the main tube and putting a plug in the head. But I had to pull the head to be able to weld that darn tube up. But any way it solved the problem.

 

[working dog 7]

thank you all have found problem. there is a magnetic pick up attached to the distributor which retards timing and advances it under no or little load it had no idea what to do. so it went back and forth .smooth as a top now . till later merry christmas to you all.....

 

[working dog 7]

problem solved magnetic pick up in dist. was going haywire with no load bottom end thank you all .