My truck is misfiring at #1 and shaking bad. This only happens at highway speeds (when I'm on the highway). I pulled the plug out and checked it and it looked fine no cracks or anything fuel filter is about 6000 miles old plugs and wires about 25000 miles on them. Any help would be appreciated as I lost a days pay because my truck was running so bad I had to turn around.

 

If you can, get scan in mode 6 to see if you have a injector or possible coil problem.

 

What is mode 6?

 

...

 

# Mode 1: graphs or displays current data
# Mode 2: retrieves freeze frame data
# Mode 3: monitors diagnostic trouble codes
# Mode 4: clears emissions related data
# Monitors test parameters and results, which include:

* Mode 5: oxygen sensor monitoring
* Mode 6: non-continuously monitored systems
* Mode 7: diagnostic trouble codes detected during last drive
* Mode 8: evaporative emissions testing

# Mode 9: displays important vehicle information . These are the functions of a diagnostic scanner not a AZone code reader. As you see 'Mode 6' monitors activity in systems like misfires that would show firing activity. Fords are a little tough to read with a scanner, but someone with Ford experience can.

 

Where would I get this tested at?

 

I would almost bet any thing they are plug wires, i had a set fail with not even half the miles you have on yours. Had the same problems, twice actually. Fixed with new plug wires. The funny thing was they were the last thing i looked at cause they were pretty new, Sure enough

 

I had the same symptoms and the coil passed the primary and secondary resistance tests so I moved on to replacing other stuff. Turned out to be the coil. If you can, save the trial and error and see if you can have the scan done somewhere.

If it is the coil. They're easy to replace. Just don't lose track of where the wires go.

good luck

 

I already switched the wires with new ones and another coil pack before and got the same thing. A mech. told me that it could be a injector or the fuel rail. Also I am now getting a miss on cyclinder 3 as well. crap

 

Hi flareside, The problem you seem to have. Was the same problem I had I bought a code scanner I told me I have a misfire on cyclinder 3 I replaced the # 3 coil and all the coil on plug boots on the rest of the plugs. When I pulled out the # 3 coil I found red dust on the boot also the plug was loose. I check all the rest and found same thing. Replaced all the spark plugs with Bosch platinum +2 it seemed some of the plugs went bad. also the truck dos not shake any more and the truck starts faster now before It would take 5 turn overs sometimes more before it would start now I have more power and better driving ALSO remember to put eletrical grease on the bottom of boot and on the ceramic part of the spark plug Hope this works for you as it did for me I replaced my plugs at 60000 mls had to replace them again at 78000 they went bad to fast

 

Also the 02 shot back a p0171 code lean condition (bank 1) on the problem side. Thanks to all the responded so far.

 

If you received an PO171 , this means your O2 is doing it's job correct ? If that's what you mean, that's right. 171= Vac leak, DPFE or MAF Sensors Faulty.

Misfire at highway speeds is most likley coil failure - 90% of the time. Coils usually pass primary and secondary but fail under a load after 45mph. Mode 6 - is cylinder history readings done with the dealership computer scanner.

I would replace the coil first, then reboot the computer , your O2's are reporting lean because your dumping raw unburned fuel down cylinder #1.


Wait a minute, Flareside - What Brand plugs do you have in there?

 

It could be a vac leak last week my heater switched from panel to defrost all by itself. Could a vac leak be the cause of 1 and 3 cyclinder misfires?

 

NO , I asked , what plugs are you running? You want help or not?

 

Your problem can't be vac. Your coil runs on electric If the items you replaced are not working then check your injectors, The injectors went out in my 1988 chevy berreta.The car would shake real bad and then die out. I had 3 injectors go bad, sold the car a year later. also when you replace you spark plugs check vin # for correct plugs. My 2000 5.4 f150. Ford made 3, 5.4 engines that year