hicks1023

Im new to the forum so, and Im sure this thread has already been started somewhere but i cannot find it. so here is my problem, i just bought a 93 f150 5.0l and i have a slight miss, and shutter once the truck warms up. Ive gone through the entire truck with a full tune up, and more. New plugs, wires, cap, rotor button, coil, coil pickup, fuel filter, and speed sensor(to fix a jumpy speedo). i am still having this miss even after replacing all these things. Ive looked over the wire routing to make sure im not getting any crossfire. ive also checked and rechecked all the vacuum lines and i have no leaks. ive also looked at the injectors and all seem to be working as they should. good fuel pressure all the way up to the injectors. please someone help, im tired of putting new parts on and not being able to correct the issue. anyone else had this problem?

mikeaj92

Well, so far you sound like me.

I have same year and engine. Just bought the truck and 'wants' to run good but had a miss. I did a plug check, and noticed one plug did not make the truck idle change. Looked further and did a pressure check. No pressure.

Now, a week later; I got the engine in pieces and the same cylinder (7) had a warped exhaust valve. It was way out, you could spin it and you can easily see the wobble (once it was out)

I am doing a head/valve job and noticed a few other things that caused her to run rough, including a gummed injector that caused a extra lean (and white valve) cylinder. There was over 1/16th" of rock hard carbon built on some of the intake valves and don't get me started on the incorrect valley silicone seal installation- which caused a oil leak since I bought her.



LLLOOONNNGGG story short-- do a compression check.

hicks1023

Thanks for your input on this man, but i have done a compression test already on the motor, and on a slightly warmed up motor i was getting about 140psi on each cylinder. From what ive seen, and know this isn't to bad for a motor with 200,000 original miles. im at such a lost right now with this thing because all the ignition system checks out, the vacuum lines are all good, and the fuel system check out as well. I feel like if it was something major a code would have been thrown by now but nothing yet, thats why i think its just something really simple stupid.

fomoco998

A long shot but I have had a-zone wires that when motor was warm they lose resistance . 2 wires checked bad when hot . Pulled my hair out Guess you get what you pay for. If I remember they were Bosch brand .

hicks1023

The brand wires that are on the truck now are pace setter wires that i got from rockauto for like $10. I had bought them for my other truck but never put them on so when i did the tune up on my current truck i just used them. They seem to be working fine but maybe they are losing resistance like yours did once warm.

seschenburg

How would one know what is a good resistance for plug wires?

Energized

When i got my 93 5.8 l it had a bit of a stumble, got about 7 MPG and smelled badly of fuel, i changed out the Injectors and it runs great now, gets between 12 and 13 MPG now too, all city driving.

I know that's expensive so i took a chance and bought some refurbished ones, i'm glad i did, made all the difference to this old girl and didn't break my wallet either.

http://www.ebay.com/itm/Bosch-Flow-M...-/200902253767

seschenburg

Or you could rebuild your injectors for around the cost of one replacement.

http://www.mrinjectorparts.com/

And here's one video about how to clean them -

hicks1023

So lastnight i replaced those junky pace setter wires with Motorcraft wires thinking that the pace setter ones were just causing crossfire, and not making good contact. Well sure enough just like everything else that ive done to this truck to get rid of the miss, the new wires didn't fix a thing. Ive listened to my injectors several different times, and they sound like they are hitting just fine. Even though they sound good is the chance still there that they are not jetting, and atomizing the fuel into the cylinder good?

seschenburg

I suppose that's possible, but I make no claims to be an expert at any of this. Have you tried running a can or two of Seafoam (or your favorite brand of injector cleaner) through it?

I have a similar issue with my 94. It runs, and runs well much of the time, but at other random times it's just not smooth. This is after an engine swap so I'm still gathering clues and hoping to see what you find out about yours.