I've been having issues with my truck the last little bit, and doing a search seems it may not be an uncommon problem.

A few weeks ago noticed a shaking/shudder/miss more noticeable around the 1500RPM mark, and far more noticeable while I was towing a trailer.

I changed plugs and fuel filter and everything was good, truck was running great and towing like a champ. About a week later I was towing the trailer to a job site and problem came back. Did a little research and found that people had problems with non OEM plugs so swapped them out to Ford's plugs. (first change out 6.5hrs, second down to 1hr 45, lol) No real change after swapping back to ford plugs.

Even while this is happening I rarely get a code, does the computer keep a record of codes, even if the SES light isn't on? I can get my hands on a reader if that is the case.

A couple of things that have come up is the DPFE sensor - which I noticed had a cracked hose when I did the second swap - hose was changed as soon as I noticed it.

Possible I have a bad coil. Aside from these is there anything else I should be concentrating on?

Thanks guys.

 

Could be a dirty MAF and throttle body.

 

Its probably a bad coil. The ECM will store codes.. If the CEL comes on you have a stored code. Generally once it sets a missfire code the light stays on until the miss is corrected. The coils do wear out. Many on this board just replace them all with the inexpensive e-bay coils. Some times with low grade missfires the ECM doesn't detect it for awhile so you can have an intermittent miss and no CEL.

 

Had the codes checked and it is P303(?) but random misfire code. Cleaned the MAF sensor and no change. If it is randon it leads me to believe its not a plug or coil. Right now when the truck is cold there is no problem but when it warms up it gets worse. Going to try changing the DPFE sensor tomorrow to see what happens.

 

Not sure how your drawing your conclusions, but you need a new coil for #3. Very common problem.

 

Yep. yer barking up the wrong tree. you have at least a bad coil on #3. Just saw you put in plugs so you dont need those unless you used some weird kind like bosch..

 

P0303 Code - Cylinder #3 Misfire

Technical Description


Cylinder #3 Misfire Detected
What does that mean?


A P0303 code means that the the car's computer has detected that one of the engine's cylinders is not firing properly. In this case it's cylinder #3.
Symptoms


Symptoms may include: the engine may be harder to start
the engine may stumble / stumble, and/or hesitate
other symptoms may also be present
Causes


A code P0303 may mean that one or more of the following has happened:Faulty spark plug or wire
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector
Burned exhaust valve
Faulty catalytic converter(s)
Running out of fuel
Poor compression
Defective computer
Possible Solutions


If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.

If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors

 

I'm just going by what the shop told me, guess I won't be going back there again. All brand new plugs, twice. I'll try the coil on number 3 and go from there. And stay away from that shop. When they told me the code I specifically said "oh # 3 is bad" and he said no its a random missfire so no way to tell which one. *&^$*&^^%, would have hd this done long ago.

 

I suggest you move the coil from 3 to 1 and see if the miss move with it.

 

I rarely get a code, which I found odd. I'm just going to change the coil on #3 and see if it fixes it.