I've been looking at this board for a long time, but wanted to sign in and say thanks for helping me fix a problem recently. I have a 1999 f-150 with the triton 5.4 liter and it has had a mild stumble for a long time, over the last two weeks it got a really bad misfire that shook the whole truck when driving under partial load (never noticable at full throttle or rolling along at idle). It was so bad it felt like the truck was going to shake itself to pieces when it happened.
It was intermittent, so it was tough to track down. I spent a bunch of time looking through old messages here and got some ideas.
I finally got a check engine light and was able to read the codes - number 4 cylinder was misfiring. I moved the coil pack to a different cylinder (number 1) and the misfire followed it. So I replaced the coil-on-plug and everything is runnign great. It was about $50 and it feels like a whole new truck. I think it was not working right for a long time - it felt like I gained another 30 hp once I replaced it! And the rough idle I used to get sometimes went away too.
By the way, the guy at the parts counter said that the coils have been superceeded like eleven times. Supposedly the new ones are better. He said the early ones were hit or miss with lot of failures.
Needless to say, I'm pretty happy that my truck is running right again. Thanks for the great info from this board!
Be sure to fix the cause of the #4 coil failure or you will be making this repair again. It is due to a leaking heater hose clamp above the #4 coil. Replace the hose clamp with a constant tension type. I believe replacement of this clamp is covered under a TSB and is covered under warranty.
Thanks! I feel lucky to have fixed it. These computerized cars really make troubleshooting hard. Even though it was running like crap for a long time it only threw a check engine code three times. Fortunately it was when I was doing work on it. I bet $$$ it would've gotten a "can not reproduce" from the dealer service department!
OK, I did re-tighten the existing clamp on that coolant line, but I will replace it now. Can I get the "constant tension" clamp from a parts store, or do I have to go to the dealer? Will they know what I'm talking about if I ask for one of those or does it have different names?
I'm not sure if the "constant tension" clamp can only be gotten from the dealer or not. Other types of clamps may also work. Mine was fixed under warranty and I hadn't paid any attention to the kind of clamp the factory originally used. The "constant tension" clamp is made of flat spring steel. The ends of the clamp form a knife & fork with tabs sticking out. The clamp is loosened by squeezing the tabs together with a plier. They've been used as OEM clamps on water hoses for as long as I can remember.
how did you read the codes that showed which cylinder was mis-firing?? while i was having the same problem, i attempted to read the codes by holding down the odometer button, starting the engine, etc.. but no luck..
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