Now I'm frustratred...My truck started misfiring - 2001 Screw, 5.4, 70,000 miles. So, I put autolites in it. Plenty of dielectric. No help. repaced the boots from the coil to the plug. Again, plenty of dielectric. No help. Cleaned out the dielectricand sanded the connections, no help again. No check enginelight at all. No water in the plug housings. Checked the low side of the coils, all are the same. Misses cold or hot, between 10% and 30% power, usually up hill (Light load).


What do I do next??? Ford garage says I've done all that they would do (For considerable more money I might add) They want $78 to connect to their computer and do a load analysis.

Which way do I go. At this point, I'm getting good at coil and plug removal. I'll try and report on any suggestions. Ice cream or a cold one to the one that solves this...

Thanks

 

Had a similar problem on a 5.4L 2001 Excursion. Purchased 1 coil from Advanced Auto for about $49 and replaced the #8 coil. Problem persisted so I took the coil I had removed from #8 and put it on #7 cylinder. Problem corrected. I hope you can get it in only two tries - but you get the idea - keep swapping coils until you find the bad one. Good Luck.

 

1. check PCV hose for cracks
2. check EGR ports at throttle body,most probably clogged
report back after these

 

Sure it's a miss? Does it happen under heavy load, like near or at WOT? Trans shudders have been mistaken for misfires often times and vice versa...been bitten a few times by that one myself, thinking a torque converter's shuddering when in reality it's a coil breaking down under load, or a misfire when it's a torque converter shudder, most commonly on 2-3 and 3-4 upshifts under light load. Does it do it consistently regardless of speed? Can you make it do it steadily, or does it happen briefly then go away? What gear are you in when it starts missing?

We'll figure this thing out one way or another.

 

Try changing the fuel filter. That was the source of a very nagging misfire that I had for a very long time.

 

Possible, but unlikely. Restricted fuel filters generally show themselves under heavy load, when demand for fuel is at it's greatest.

But with 70K miles, if it hasn't been replaced recently (like within the past 20-30K), replace it anywho, it can't hurt.

 

Yea, I'm pretty sure its a miss. It occurs between 1100 and 2000 RPMs, worse on a slight uphill grade with light - 10-20% throttle -beyond that it goes away. No issues at WTO, even half throttle. I have never changed the fuel filter, doesn't that require a special tool? I'm going to try your suggestions in the next few days and I'll let you know.

PS - the trip home from the ballfield tonight ~10 miles in various driving conditions, NO MISS!!!

Boy, this is frustrating!

Thanks for your help.

 

injector cleaning cured my miss

 

Rickinport,

I have a 2000 F150 5.4 with 81000 miles and I have the exact symptons you do. I have a miss mainly during slight excelleration with the throttle open part way. The miss is more noticeable when it gets hotter out and sometimes it does it during idle. It really makes me mad because last weekend I changed out my spark plugs with Motorcraft and the truck was running fine with no problems before the change. I have pulled off all the coils and checked their resistance which were within spec. I also pulled all the plugs and re-checked their gap which were fine. I have purchased 4 spark plugs and was going to change out each side to see if maybe I have a bad plug. I hate to spend $50 for a new coil but based off of what I have been reading in other posts, it's probably a coil and not the cheap fix of a bad plug. I think I will stop and buy a new coil and start replacing at each cyclinder until it goes away. I will update what I find this weekend.

 

You'll need these:

Fuel line disconnect tools

to disconnect the fittings on the fuel filter.

How long since the transmission has been serviced?

 

Why not just pay to have it diagnosed properly?
You will spend more money "beating around the bush".

 

Transmission was serviced @35,000. I know it is time again and I plan to within the next two weeks.

I have not taken it to the garage because they want $78 to hook it to their computer, and it is not throwing a check engine light. The dealer is not sure that hooking it up will tell us the problem. So far, I have around $120 in my repair path, incliding tools to do the plugs. (extensions, 7mm universal, I have the rest.)

Towed 6,500# through the WV mountains a couple of weeks ago and it did not get better or worse. Shifts were sharp and crisp. Missing was on the level at the same symptons as above...

I sure appreciate your help. I'm taking Father's Day off (Playing a little golf, cooking out, having a few malted, slightly carbonated adult beverages, and watching the miserable #7 at the Open!!!) and I'll get back to it this week. I'll let you know.

 

Rickinport,

I would almost bet you have a coil pack going bad. Does your truck have rear disc brakes? If it does, put the truck in reverse with the parking break securely set. Get under the hood and open the throttle a little to put a bit of a load on the engine (this way the truck won't run over you and the parking breakwill hold it in reverse with disc breaks). Start with #4 (pass side closest to the cab). With the engine loaded, remove the coil wires one at a time to see which one is the culpret. If you truly do have a miss, the engine will shake as soon as you load it a little. If it does not shake, you don't have a miss.

Ford has a TSB out to reprogram the trucks computer. It is basically a new algorithm for the intake air temperature sensor. Evidently, the temperature read by the sensor is causing the timing to be retarded too much. I had mine reprogrammed last week because I was noticing that my power was falling off in hot weather---I pulled my 3000+# camper across the Blue Ridge Mts this past weekend and the 5.4 never missed a beat---I believe it made a difference.

I can get you the TSB# if you want, but my dealership paper-work is at home--will have to be tomorrow.

Sidewinder

 

ok...my truck had a rough idle before so i decided to change the spark plugs....i put motorcraft platniums in my truck and gapped them at .054( is that the right gap?? thats what the website for motorcraft said i think) well neways...now my truck is really rough idle and when you hit the gas hard it is very very slugish the truck wont even get past 4 grand on the tach when before with the old spark plugs it would easilly redline....some mechanic guy told me how to put them in and he said not to tighten them to much just tighten them as much as you can with your hand...is that right or should i take a rachet to them?? PLEASE HELP ME I AM IN DESPERATE NEED OF SO ASSITANCE ON THIS PROBLEM!!!!

 

My 2001 5.4 Supercrew would missfire during highway cruising with a slight uphill grade. No CEL or codes could be found. I changed the plugs and measured the resistance of all the coils. Nothing worked for me. However, since the problem/description is very similar to many on this website, I decided to buy a new coil from EBAY for $25. I started with coil number eight and worked my way on down. when I changed coil number 5, the problem totally went away. Nice not to have that problem anymore.