This morning when i went to leave for class my truck was missing really badly. Up untill this morning there have been zero issues with this truck for two or three months. It was cold enough that i needed to scrape my windshield before i left. while i was doing this, i let the truck warm up and i was fine. i backed out, and put it in drive and instantly there were drivability issues. i limped it to campus because i had no other way to get there and it did get better the farther i went but there is still a miss. it idles perfectly. there is no CEL either. I am hoping its as simple as water freezing in the fuel line or bad fuel. I'm going to put some fuel dry type stuff in and fill the tank back up (sitting at half a tank now) Right now i am at a loss as to what is causing the problem and really would appriciate some input as i have to drive back home two and a half hours tonight or im gonna let some people down tomoro.

thanks for any help

truck; 97 f150 4.6 4x4 off road extended cab with 188000 miles.

 

Start thinking spark plugs, wires, coil packs.

 

x2

Check for water/condensation on the coils/wires

 

Don't keep running it like that or you will be in for a big hassle and expense with failed cats.
They are not chump change in cost.
Good luck.

 

Had that problem and it turned out to be a bad coil. Took to the dealership even without a code. They diagnosed it as bad coil and later set the code. I then took it back home and changed the coil myself as I had spares available. Was bout $125 or $150 for them to diagnose it but when you dont know whats wrong you gotta do what u gotta do. Woud have been about $500 total for them to fix it.

 

well after putting the fuel dry in and filling the tank, it seems to be ok.... but i dont know for sure. the miss is definately not there any more. so what do i do now that the issue is no longer there to check/ test for? i wont have time until thanks giving to do a full plug change. Ill check for moisture around the coils and see about at least changing the wires tomoro.

thanks for the replies i appriciate it. now that i think about it, i dont know if the coils/ plugs have ever been changed or not....

 

I know that as far as plugs go, to use motor craft, but when it comes to the coils and plug wires, should i also go motor craft, or would say AC Delco's be just as good? the only reason i ask is im trying to save some money (and i dont want to order parts online). now, yes the motor craft coils and wires are more expensive, but i'll pony up for them if they are worth it in the long run.

also, what is the number/ name of the plugs that i need?

Thanks again

 

You may not WANT to order parts online, but there is a HUGE savings if you do.

Plugs: SP-432, $3.50
Wires: WR-5934, $60.79
Coils: DG-530, $63.99

Prices are from rockauto.com. You may not need everything - I'd change just the plugs first, and if it starts missing again, then change the wires. Coils would be the last thing to do.

 

Well, after being fine for almost a week, the ol girl did it again. Since there aren't any orielys in town here (to get motorcraft parts), I ended up having to go to Autozone and I picked up a set of bosch wires. I started installing the front four wires and found this



It looks like it rubbed itsell on the alternator, but I dont think it was my problem and I dont think it wore through enough to cause any issues, but I am glad I found it before it got worse.

Any way, at first I thought it might have been the issue the whole time so I stopped with the front four wires and went for a drive. It was still missing under accelleration and a little at idle, but before I could find a place to turn around and come back, it comepletely stopped having issues and ran perfect. so I drove around campus for about 15 minutes in stop and go traffic and all seems to be ok at the momement, in fact, the ol girl seems to have just a little more pep. I am going to go ahead and try to get to the last four wires in the morning and see how that goes.

I think my next step is going to have to be my coils. other than that I am out of ideas other than plugs and I dont have the nessesary set up here at school to tackle that job, so that has to wait untill thanksgiving.


Would a bad coil explain the intermitenness of this issue? As best as I can tell there doesn't seem to be any coolant leaking on the back plugs so i dont think that is my problem. oh, and still no trouble codes

thanks guys.

 

That wire could definitely of been the problem of your mis. The white part you see is the last part before the conductor inside. That was grounding out on the alternator intermitently causing your problem. I have seen wires that looked almost new arc out the side if the jacket causing problems. With a wire grounding out like that on it won't throw a code. Only if a coil is bad and even then it won't always give you a code.

 

Thanks for the reply. And initially that was my thought about the wire, but then after i replaced it, and went for a test drive, the miss was still present at first. That made me think that it couldnt be the wire, and had to be something else. I am going to attempt the back four wires today just so they all match and maybe i will find something else wrong. If this miss comes back would it be safe to say that one or both coils is to blame? I kinda thought that an outright bad coil would cause a constant miss, not an intermitten one.


Oh yea nice looking truck you got there

 

You see the thickness of each layer in the plug wire?
It's there to keep up to 40,000 volts under control.
You can't dismiss the wear through so easy. With that wear shown in the photo, the voltage will punch through the remaining insulation.
Also there is a carbon center core that cannot be broken from misshandling and sharpe bends.
You may well have more than one issue by now.
A missfire usually is recorded in PCM software phase 6 memory.
A coil can very well be intermitant and temperature sesnitive.
Have it looked at and find the cylinder if no code is set for a CEL lamp.

 

So you are replacing the plugs right? didnt see glancing over the thread where you say you've done that but I could have missed it. if you haven't done that do it and also change your fuel filter if you haven't for a while. If you live in a cold area this time of year fuel thickens when its cold a bad filter will cause misfires and its a maintenance thing anyway.

 

I am at school right now, (two and a half hours from home) and dont have all of the tools or space or time i need to complete a plug swap, but that is definately on my list when i get home for thanksgiving break. and the fuel filter is about a year and a half old, so i would assume it is still good. although it does probably have over 10k miles on it.

on a side note, while i was doing the back set of plug wires that i didn't get to last night, i did noticea miniscule leak over top of the passenger side rear plug. This leak was so small that i only noticed it when i ran my finger under the conection of the rubber hose to the metal line. I have now added this to my thanksgiving break list of things to do just in case.

i think a combination of this leak and the bare spot in the plug wire were working against me and finally caught up to me and caused this issue.

 

Yeah thats the heater hose leaking and that will definitely cause a misfire..