i have a 2006 F250 with the 5.4 gas eng. the engine misses when you lug the engine in overdrive. cruising at hwy speeds it runs fine. when you start up a hill in overdrive it starts missing. you can kick it down out of overdrive and it quits missing. any ideas??

 

yeah, it sounds like its a ignition coil or spark plug breaking down under load, the ign. coil on plugs are known for this. can you duplicate the problem by powerbraking the engine? also any codes stored in the pcm...may lead you to the cyl. affected

 

OH!! I thought someone STOLE the engine!!! heheheehe

Seriously....sounds like a plug or boot. Get the codes read. It should tell you which one (s).

 

thanks guys, i'll get those codes pulled and go from there.

 

I had the same exact thing. One plug and another boot on a different plug. I sometimes wonder the thinking involved in having a coil for each plug.

 

Get a code reader that will read PENDING CODES.

 

took the truck to Autozone today and had the codes read. no codes so i decided to change all the plugs and boots. WOW! 12 bucks each for the plugs and 15 bucks each for the boots. i sold a diesel truck last year because it was to expensive to work on!! one molre thing. i have a tapping noise comming from the front of the engine sounds like its comming from the right bank head up front. took it to a local mechanic he says its the timing chain. and will run around $500-600 dollars to change both chains. anybody agree with this. the truck has 128,000 miles on it.

 

That is a good way to see if you have a locking differential too!

My first thought also.

If you bought Motorcraft platinum plugs, which you should have, then you got ripped off! Motorcraft SP-479 for $3.49 each and Coil boots for $4.49 each

Possible, but get a second opinion.

 

Did replacing the plugs and boots fix your problem with the uphill cruise control? I know someone who is having the same problem.

 

No it did not, I sold the truck some time back but when I took it in to get the timing chains replaced there was nothing wrong with them. I had a rocker arm broke on one cylinder and it had damaged the cam on that bank. Cost me $1400 to get everything replaced.

 

One more thing,I had a 2007 F150 with the 5.4 in it. It started missing under load. Would run fine out on a flat road with no strain on the engine but put a trailer behind it or have it in cruise control and start up a hill and it would buck and jump bad. It never did throw any codes either. Took it to a local mechanic and he found the # 1 coil pack was going bad. Replaced that and that fixed it. As bad as it would miss it should have thrown a code but it never did. One guy told me he had the same problem and he connected a code reader to the truck and drove it until he could get it to misfire and the code reader caught it.

 

Ok thank you. My grandpa is the one with the problematic truck, and the mechanic said codes popped up on #4 and #7 when he tried to recreate the problem. He replaced one of them but the problem was still there. He is hesitant to replace the other because he was charged over $100 for parts and labor. If you are pretty certain that replacing the other will fix the problem i will suggest that to him. Any input would be great. Thanks again

 

My 2002 F-350 had the same problem with the 5.4, it threw the code misfire #4. I really like the coil for each plug because I can determine if the coil is bad by simply switching the #4 coil with the #1 coil and if the misfire moves to #1 it tells me that coil is bad. When doing that, I went ahead and replaced all 8 plugs. When I was done, there was no misfire. My coils were fine, it was the plugs. It took me 6 hours. However, I took my time and cleaned everything and reinstalled using anti sieze on the threads and di-electric grease where it was needed.

 

We'll like uncle Phippy says you can switch the coils to see if it's a plug or the coil. I don't remember which models for sure but certain year models of fords with the 5.4 are a bitch to change the plugs. I took the 07 F150 in to have the plugs changed because it's one of the screwed up models and they broke 3 of the plugs off in the head. Cost me $400 dollars to change all the plugs because of that. The local ford dealer wanted $600 if none of the plugs broke. So make sure your truck is not one of the problematic models before attempting to change the plugs yourself.

 

Check this link for troubleshooting the coils. If you need a video on checking the injectors and or the MAF, let me know and I will post those.

https://www.ford-trucks.com/forums/1...h-misfire.html