Forevernew

Just registered, been reading on it for years (as a guest), Great Site!

My '03 F150 has been a great vehicle for me, 122,000 miles and hoping many more.

First time I have had an issue with it.

Started to misfire a week ago and check popped a code that Cylinder 1 misfire. Changed the coil pack and the spark plug and everything ran great for 2 days. Third day misfire when giving it gas. Ordered a full 8 pack of coils from ebay for $115.00 and just swapped out the remaining 7 coils and plugs. Ran great for about 10 miles and started to misfire again. This time I no check engine light, watching for it I noticed that the theft light occasionally flickers on. Playing / testing at any speed if I let off the gas completely and tap the gas pedal the theft light will flicker every time and it will misfire at roughly the same time. Watching closely the theft light does flicker when the engine misfires. PAT module bad? Thought the jerking when it misfires causing theft light to flicker but ruled that out by traveling rough road and not getting a flicker. Has to be PAT module occasionally cutting me off?

Thank you in advance, I do appreciate any help / advice.

Thanks!

Russell8833

I have the same problem, Mine occurs after about 5-10 minutes of driving, and when it's cold.

I took it to the dealer and the weather was so much warmer the week that they had it and it ran great. They found no issues with it. I thought it was bad gas so I topped off with a tank of good stuff and fuel treatment. No issues until the weather got cold again.

The Check engine light comes and goes, but the engine will sputter from time to time after about 5 minutes of driving at lower RPMs.

If this sounds like your truck and you figure it out please anyone let me know whats up.

The truck had a Full tune up (replaced all the plugs) and service in Feb 08 and another service in July. No issues until Oct 08.

torkum

First question: Have you guys tried using your other key? This probably is not the problem but needs to be eliminated from the possible causes.
Do make sure you have proper battery voltage.
Gonna do some digging, this is a good one.

Forevernew

Turns out one of my new coils are bad, it was backfeeding some of the charge back into the system. My problem was that the check engine light would not pop, I took it to a local shop and they said that the light came on when they were test driving it and it popped up as #6 cylinder misfire. Changed that coil out and all is good.

Thank you again for your input!

Russell8833

2004 Ford F150 4x4 Larit Mileage 119,403

I don't think it's a Coil, and I tried the orignal back up key (thanks for the idea) Still have the same problem. Today on the way home the engine again sputtered after about 5 minutes of driving.

It happened at 43 MPH and as long as I held the same speed it continued to sputter. When I go faster or slower it goes away. Then the problem does not come back. Since I let it sputter for about 30 seconds I got a check engine light again that went away in about 30 seconds.

The Fault code was 304 (cylinder 4 misfire) and 316 (Misfire Detected On Startup (First 1000 Revolutions)

Before it was code 301 and 303, misfires on 1st and 3rd cylinders on different days.

I really hope someone can solve this before I have to spend the Christmas money on a great old truck!!

Russell8833

The problem got worse yesterday. I have a check engine light on all the time now with codes p0171 (left bank lean) p0300 (multiple misfire) p0303 (cylinder 3 misfire) p0304 Cylinder 4 misfire) and p0316 (Engine Misfire Detected on Startup, First 1000 Revolutions)

it appears All the problems are related to One side of the engine Cylinders 1-4 and occur after 5-10minutes of driving.

But here is the best part, after the engine warmed up (about 30 miles of driving), I have no more problems! it runs great, and today it drove just fine. The check enigne light is still on but I believe that once it cycles enough it will go off.

I normally only drive the truck 8 miles a day, 4 to work and 4 from work. The truck never warms up completely either way. Could this be some kind of build up? or is it fuel related? I have added Fuel injector cleaner the last two times I filled up, and once topped off with 93 Oct gas.

If anyone has any ideas please voice them thanK You.

fordtruckman2004

i have all the same codes in my 2004 f150 5.4 i changed the plugs and the thrid coil and coil f and no change its bad in my truck it misefires just at idle real bad then the rps move up and down without me touching the gas also after i get my truck up to forty it jerks and shakes really bad and i have to slam on the gas to get it to stop and go faster i think we are having the same issues mines just alot worse i hope someone can help us out

torkum

Man you dug up a old one Being that you have a '04 I would be looking at a problem with the injectors. '04s and '05s had injectors that stuck open.

Stinky Buffalo

Russell or Fordtruckman, did you ever get your trucks fixed? Did you figure out what the issue was?

Cheers,
Stinky

Russell8833

It was a bad injector that damaged the exhaust resulting in the replacement of both