Since new coil packs are so expensive you might want to keep an eye out for a good value on a used set (with low miles) I found a "totaled" Mustang Cobra with less than 2000 miles on it. I made a note of the serial/model number from one of the coil packs and went to the Ford Parts Department to find out if the part number would cross for my 5.4 Expy. They said the part wouldn't work... that I would need to buy all new coil packs. I thanked them for checking and went to Advance Auto. I asked them to look up the part number for replacement coil packs on a 99 Expy and again for a 2001 Cobra...big surprise...the same packs are used in each vehicle!

I picked up the 8 slightly used coil packs for $50 and new double platinum plugs for $32. Using the links in these threads as a guide I was able to replace the works in about 4 hours. Also, I did not have to remove the fuel rails from the injectors on my 5.4 , simply unbolting the rails from the intake provided reasonable "wiggle room" to work around. I was able to use a 7mm socket on a 1/4" drive with 2 extensions seperated by a flex-knuckle to unbolt 7 of the 8 coil packs. The only access problem due to a fuel rail was on coil pack number seven (driver's side 2nd from rear). It was marginally accessible with a 7mm combination wrench, took a little while - but it worked. For the plugs I used a 3/8" drive in combination with a flex-knuckle, a 3" extension, a 6" extension and a 9" extension as needed. I also found it very helpful to have a standard 5/8" deepwell socket as well as the 5/8" spark plug socket w/felt insert. Also, an 8mm socket was used to remove the intake cover and to move the steering fluid reservoir.

Glad I made the change as gaps on the old plugs ranged from .0065" to .0070". MPG has improved and it runs very smooth. All in all, beats the heck out of paying a dealership $1,000+ for a full set of plugs & coil packs installed.

Hope this info may be of some help, and please remember, if you do decide to condsider used packs...before you buy... please be sure to check the compatibility of the possible application for both vehicles through an Auto Zone, Advance Auto, or O'Riellys, etc.

 

I had an identical problem with my '97 f150 5.4 Mpotter. I would be willing to bet it's not the transmission as it wasn't on mine. Just as all the other evidence shows it's another plastic Ford weak point-the coil. I took the truck over to the neighborhood dealership where a friend scanned it for free during his lunch break. It was #3. I solved that after replacing it.

Now I'm confronted with another problem, an occasional rough idle. I don't know if it's another coil problem this time or if my intake system is gummed up. Ideas anyone?

 

I had same problem.... Herky jerky when applying light acceleration while at low RPMs.

Bad coil was replaced and fixed my problem.

 

My 2001 Supercrew 4.6 has a slight stumble at low rpm and you can feel it shake when in overdrive and it tries to downshift. I have brake torqued it and it does not seem to stumble. When you get the rpms past 3 grand then it seems to run fine. The motor does not seem to have the same pep it used to but I also think that 71000 miles might have something to do with that. Have already replaced one Coil pack but that gave me a light and had a failure code. The dealer could not find anything wrong and I am hesitant to take it back...any ideas? I would hate buy all new coil packs but I do need to change the plugs and I could do both.

 

exactly the same problem here,f250 107,000 o-40 mph like a dream40-55mph feels like the truck is shaking every nut and bolt loose 55- upwards like a dream again, just done complete trans flush and service still no joy.........check engine light illuminated all the time .....holds the idle well although a slight sign of gagging for breath...but not always..........new to the usa ,so i'm certain im going to get ripped off ......needs help, thanks in advance

 

Dennison, the problem you have described, is a classic weak COP symptom.

A weak COP will be most evidenced at around 35 mph in overdrive, under light acceleration, just below the point where the tranny is about to downshift; but it runs okay at high rpm.

Not sure what you mean when you say "I have brake torqued it and it does not seem to stumble"; But I'm guessing that you are placing the engine under load with a stationary vehicle, and the brake on. That generally won't work, because you are not duplicating the driving conditions under which the misfire occurs. The PCM will assign entirely different operating parameters to a vehicle travelling at 35 mph at 1/4 throttle, and brake off; than a vehicle travelling at 0 mph and brake on.

You don't say which DTC you were getting, so that's not very helpful, notwithstanding that even if you did know the code, it still might not be all that helpful. Sometimes, all the code will tell you is that you have a multiple cylinder misfire.

The easy way to diagnose a misfire, is with a scanner that provides manufacturer-specific codes, plus the ability to read mode $06 data. Mode $06 data contains a misfire counter for each cylinder, and will quickly identify the culprit. To acquire enriched peretinent data, hook up the scanner, and then take the vehicle for a drive and attempt to run it as long as you can, a minute or so, while the misfire is ocurring. Do a scan a the end of this event, and then check the mode $06 misfire counter for each cylinder. This should provide you with pretty clear information as to the source of the problem.

For anyone who maintains their own vehicles, stumbling around in the dark without a decent scanner, may well cost you far more than investing in something that you are eventually going to have to buy anyway.

Something like the Autoxray EZ-scan 6000 will set you back $500, but with something like that, you will have all the feaures of scanners costing 3X that much.

 

That's commonly caused by a contaminated MAF sensor. Disconnect the MAF and take it for a drive to see if your vehicle has a lot more pep. If so, your MAF needs to be cleaned, or in rare instances, replaced.

 

It probably won't run much with it disconnected. Just clean the element in it with carb cleaner or brake and parts cleaner by spraying it and not touching it (they are very fragile) There is a good how-to in the 97-03 forum in the FAQ thread.

 

A vehicle will run fine with the MAF disconnected. The PCM just takes the MAF out of the loop, and reverts to the default system parameters.

 

my original post
I am currently experincing the same problem on my 2001 f150 with the 4.6l engine with 65,000 miles. seems to be the same problem while in overdrive and lightly acelerating get the miss and jerking. i have paid $100.00 to have this checked out and was told there is no codes and when they hook up a computer to my truck it picks up the third or fourth misss in a row but wont pinpoint which cylinder it is. i have been quoted $350.00 to change the plugs and visualy inspect the coil packs but have been warned no guarrentes that this will solve my problem. also if i put the truck in gear and have my foot on the brake and rev engine up slowly i get the miss at about 1200 to 1400 rpm which seems to be the same as when driving and in od. i had the transmission serviced two weeks prior to this problem.

8/3/04 above problem went away on its own in summer of 2003. winter of 2004 on a very wet rainy day my truck sounded like the engine was comming apart. check engine light came on and stayed on. i belive the code showed #5 & #6 cylinder as the problem. turns out when they pulled out the coil assembly water poured out of both coils and when they pulled the plugs they looked rusted. appears like water built up in plug area. as of now no problems.

 

changed the plugs and found fluid in the drivers bank down in the spark plug holes. So far truck is running good and no miss.

 

I had the same problem with my F-150 w/5.4 took it to the dealer the technician said #3 COP was bad and also recommended all 8 plugs be replaced..well $559.00 later that was done. This weekend less then a week after the repair the miss has returned tho not as severe or as often it still misses every once in a while. I might add before I took it to the dealer I changed the fuel filter and put fuel additive in it thinking I might have gotten bad gas. I love this forum it is very helpful. Thanks

 

stan birch,
i do not agree that the truck will run ok with the MAF unplugged. With the MAF unplugged, at best the truck will barely keep an idle and to keep it running you'll have to keep one foot on the brake and the other on the gas pedal.

The computer does not just take the MAF "out of the loop". The MAF is a crucial part of the computer's input as it tells the computer the volume and density of the air flowing into the engine. Without that info the computer cant determine the appropriate amount of fuel.

It is possible to keep the vehicle running without a MAF, but driving it in traffic would be very dangerous as you would literally have to simultaneously keep a foot on the gas and the brake pedal. And without the maf the truck would be prone to suddenly dying so it would be a good way to be rear ended.