I have been the proud owner of a 99 f 150 , 5.4 4x4 since it had 13 miles on it that has NEVER been to the dealer...seems I am one of the few and the proud..anyway I am almost a daily reader and a very rare poster... but I need some help...On my way to work yesterday Am ...after about a 5 min warm up and less than a mile to the interstate I was off to start my day a mile up the highway at about 70 mph it was missin bad....not coil pack or dead cylinder missing but missin none the less...CEL blinked 15 times and stopped for exactly one min then did it again ...i counted 14 the first time and 15 the second cuz i was lookin for it...on the way home still ran terrible but no light ...went to auto zone to get codes read...no codes......this morning same deal ...warm up , highway about 70, light blinks 15 times, i was waitin'...still missin.....way home same deal but no light....after the auto zone episode, i went home and cleaned throttle body thouroughly , cleaned K&N, and went for a ride same deal....fellas. i have 109k on this truck , but...I have had it for 6 years and it has been driven hard no doubt, pulled EVERTHING I ever hooked to including pulling my neighbors 56' Nortech that weighs 21,000lbs sitting on a trailer out of the water[ thank god for 4 lo] I am trying to save a trip to the dealer . Any help would be much appreciated...PS...NO MODS....K&N , 3" body . 33's 3.73....otherwise stock....

 

You may have a bad spot on your TPS (throttle position sensor) and a bad coil pack is still not out of the question. There was also a post a while back that the wires that run next to the air conditioning reservoir may cause engines to miss and the solution was to tie the wires away from the reservoir.

 

This is just thinking out loud but relating to your discription, I know that the CEL will blink on certain missfire/cat problems.
This has to do with excess raw fuel reaching the cats, burning and raising temperatures.
The computer is able to relate this and sends the blinking CEL as an indication of such a condition.
This could be the reason why there are no codes stored because the fault is not in long enough to set code.
I'm sure you will eventually see a solid CEL lamp and code.
Intermittant faults are difficult to handle until a solid fault occurrs..
As to what could be the fault, it may range from plugs, injectors leaking to something with the OX sensors or the cats.
Good luck and let us know what the fix becomes.

 

I used to have a '99 4.6. Did the same thing at about 75,000. Set of new plugs cured it.

 

If your CEL is either on, has been on, or is flashing, the ONLY way to determine WHY is to scan the computer codes. Make certain that it is also checked for pending codes and for any history. Many drones at AutoZone have no clue on how to do this.

There are hundreds of possibilites WHY the CEL has come on. Without the diagnostic codes, you're just guessing.

Scan it then post the codes for assistance in diagnosing the fault BEFORE purchasing any parts.

Steve

 

Thank you all for your responses. I think I'm gonna drive it till the light stays on and gives me something to work with or breaks real good ...Sean Hyland Motorsports crate motor here I come !!!

 

You're probably jumping the gun. You probably won't spend a few hundred fixing this. Less if you're lucky. I don't read new engine yet.

 

built yours too, where in virginia are you? The cel flashes when it detects a misfire. Could be low fuel pressure, plugs, coil packs, or about five other things. I live in the Hampton Roads area and work on trucks on the side. If you are close, contact me and we'll figure it out.

Robbie

 

Big Bronc....I live in Newport News.. E mail me Bizkit69_us@yahoo.com

 

I said that all wrong...I will e mail you...

 

since youre over 100k...how about a tune up? my friend was told that he didnt need a tune up at 100k...but shortly after that...his truck started driving poorly...he got a tune up done...and now good as new.....sounds like new and drives absoultely fine.