5.0 misfire

[DUNE RCR]

OK so I know my truck is far from stock as a whole but the engine is still very much stock, aside from the k&n filter. Here is my problem, my truck has 205,x.. miles on it right now and is misfiring intermittently. My wife and I have replaced plugs, wires, the suspected coil pack, and sprayed the intake gasket areas with Carb cleaner to rule out intake leak. I have also hand over hand traced all the vacuum lines with none cracked, broken or leaking. I am at a total loss right now because this is intermittent. Any help will be greatly appreciated as this is our only vehicle right now. I have also read through a lot of other posts and haven't exactly figured it out since others have a constant misfire, mine is intermittent whether it is hot or cold and weather doesn't seem to make any differance either.

 

[Turdle]

How do you know you have a misfire? If you are getting a code that is important to know.

I'd start by checking out the Camshaft sensor-just take off the cap, look inside, maybe blow it out with some compressed air. ( controls fuel injector timing)

Then I would look at the crank sensor--sensor trigger area. It may be dirty. Also, sometimes the rubber sleeve inside the balancer will "shift" allowing the relationship of the crankshaft keyway and trigger wheel to "migrate" (controls ignition timing)

Another thing to look for is a misfiring injector. If your misfire code is always on the same cylinder this might be a clue.
If the misfire is under load-try a new set of plugs. I've seen them fail out of the box.


other possiblities--

Are you losing coolant?
Do the plugs look "oily"
Did you read the old plugs for clues? when removing them I always keep them in order, then look them over to compare to one another.



Good luck.

 

[DUNE RCR]

Camshaft sensor and sychro are both new(replaced because the bushings in the synchro went south). I never thought to look at the crank sensor. I have gotten a misfire code on cylinder 3 and a lean code also. I'm not loosing coolant. The old plugs looked like half of them had run hot while the others had some light carbon build up. I'm kinda clueless for this because it will do it while it idles, under load or cruising and at random for these examples. I haven't pulled the injectors yet because I haven't had the time to pull everything apart, I have however heard though that when an injector fails, it will fail completely, I dont know how true this is though.

So for a recap, items that are new/fairly new:
plugs & wires
cam sensor & synchro
coil pack associated to the misfiring cyl bank(tried swapping coils too with no change)
TBS
vacuum lines(broke a couple while inspecting them so replaced as much as I could)
fuel pump
fuel filter

 

[Turdle]

Since it is intermittent, it could be a flaky connection somewhere---??? reseating all the connectors might help. Check the wiring to the #3 injector.

also reseat the PCM connector on the firewall.

An injector is merely a solenoid which allows pressurized spray to pass. It can be intermittent in it's internal coil --possibly a crack inside which opens the circuit when it is warmed up a bit. Then once it cools off it works again. I have seen this in mechanical applications before.

 

[DUNE RCR]

I have checked all connections too. I have dielectric grease on damn near everything. What else could possibly cause an intermittent misfire?

 

[Turdle]

I have checked all connections too. I have dielectric grease on damn near everything. What else could possibly cause an intermittent misfire?

For giggles you might swap the #3 and #6 wires and plugs with each other to see if the code moves to that cylinder--but I am betting on a bad, or clogged injector.

 

[DUNE RCR]

This may or may not help but just driving it was running fine, hit a bump and started misfiring like crazy. Figured I would just give a little quick possible clue. I don't know if the bump is what caused the misfire to start or if its just coincidence that it started misfiring at that point.

 

[DUNE RCR]

Anybody want to throw their .02¢ in on what they think this may be?

 

[explorinitup]

just ford ***** have you run a compression test??? may have a valve playin games. if it all good see if you can swop the injector with another cylinder and go from there

 

[Turdle]

Anybody want to throw their .02¢ in on what they think this may be?

Did you try swapping the wires and plug yet?

Did you check the #3 injector? And yes a compression test is a good thought also.

 

[DUNE RCR]

I did just change my oil to royal purple about 1000 miles ago if that has anything to do with it. But I had this intermittent problem before then too. Its a problem that has been haunting me for awhile now.

With that said, I do have good compression, could it have anything to do with the lifters? I know they are hydraulic.

 

[jremington59]

I think you should take Turdles advice and do what he suggests before going any further. Also, whens the last time you used some quality dry gas? I know it sounds silly but I got gas once and all hell broke loose. Dry gas cleared it up.

 

[DUNE RCR]

Yeah I swapped plug wires last night and it still misfired for a couple minutes this morning. Ever since it has been smooth. I changed my fuel filter again to see if that helps any. If this doesn't work I'm probably gonna go get another set of cook packs. I'm still suspecting them being my issue.

 

[DUNE RCR]

So a little update.
I changed my fuel filter again. Other one was maybe a year old(didnt realize it was that long) but apparently was doing its job. Ran good all day yesterday and has been good today with a noticeable increase in power too. Apparently I got some bad fuel somewhere but it's hard to tell since I'm on the road all the time.

So if anyone has this problem, check the simple stuff first! I will update in a couple days if the problem for sure is fixed.

Thank you all for your inputs also.

 

[DUNE RCR]

So like I had said, an update a couple days later. Well it rained all day yesterday so I decided to go puddle jumping to see of the moisture would get the x to misfire. Well going down a couple flooded roads she never misfired once, I did however get the dreaded squeak from the belt that went away but I can live with that. Again thank you all for you inputs!

 

[explorinitup]

Good deal. I like to hear a easy fix. At least you wont need a motor.

 

[DUNE RCR]

Your telling me! My next focus is getting my hands on rebuild kits for the engine, transmission, transfercase, and both axles(re-gear to 4.56) as the truck has nearly 210000 miles on all original except front axle that I blew the seals on. Any ideas where to go or what kits to go with for the rebuilds?

 

[explorinitup]

I would say summit for most of the stuff. But for the t-case i would go with the 4406. It would cost the same the switch it theN it would to rebuild the 4404. And for the 4:56 gears i would go with some 35" tires. I have the v8 with 35" and 4:56 gears and its perfect. But it also depends on what you drive too. I was the high way alot so i need a little less gear. Ooo fyi if you dont know the 4406 gives you 2wd 4x4 and 4lo. And i good amount of power back. You loose alot threw a 4404.