So, the good old check engine light comes on 300 miles after I buy this 04 f150 from the dealership. Oh joy. The engine has a slight miss at idle, makes the truck vibrate off a little. I can hear a ticking coming from the engine. I pull the codes. PO303(misfire detected on startup) and PO307 (misfire on cylinder 7). I looked up the firing order and the number 7 cylinder is on the passenger side, third from the front. Guess what? Its ticking. I was thinking bad fuel injector? I take it in tomorrow, I have a limited warranty of 50 percent parts/labor on powertrain. I wonder if that's considered powertrain to them...probably has to be a spun bearing or something figuring my luck. I'll bet they will be more than happy to charge me 125.00 to figure out that its NOT covered under warranty to pull the codes, troubleshoot, and tell me exactly what I already know. I will tell you it shakes near violently above 65, like I'm on riding the bumpstrip on the side of the highway...but much more pronounced. Maybe more like a flat tire with a brick in it? That is new too...Doesn't do it all the time. Could it be the engine starts missing and vibrates the whole driveline?

 

Maybe it's a bad COP, I had one go bad on my '02.

 

It also could be the parking brake. If you don't use the parking brake regularly it tends to rust and then when you finally do use it, it gets stuck partially engaged. This then causes the rear wheels to shake. You can check to see if this is the problem by driving down the road for a couple miles with the truck shaking. Then stop and feel the rear wheels and tires to see if they are warm and if you can smell the brakes.
You can also stop apply park break back up a few feet release break and it should free up.

 

PO301-308 I know very well, it's the coil pack on that cylinder. I've been replacing them on my 99 5.4 at the rate of one per year the last 4 years because I'm too cheap to just buy all 8 at the same time and replace them all at once.

 

A friend had a 98 F250 light duty (F150 based) and had a lot of problems with the #8 coil. Upon investigating after the 2nd or 3rd replacement he found that a heater hose over that coil to be dripping a little coolant on the coil causing it to fail prematurely. He fixed the leak by replacing the hose clamp and hasn't had any more issues.

 

Turns out. It was the dealerships fault. There was some water in the cylinder from it being pressurewashed....The previous truck I looked at another dealer the SAME DAY I bought this one had a completely ruined COP because of the exact same dang thing! Stupid kids with power washers!

 

I'm glad you got to the bottom of the issue and all's well.

 

Similar problem haunts the Super Duty's since the 2 back COP's are under the wiper cowl water likes to drip onto them pooling around the boot and making them short out. Those are the 2 IO have replaced more than once and a friend of mine who is a service manager at a local dealership tells me that is an on going problem.

 

"We" fixed one on a friends truck last week. Same deal. I was wondering if some dielectric grease would keep them dry? He did the work so I really didn't get a good look at it. I just told him what to change.

 

P0303 is misfire number 3

cylinder 7 is the on the drivers side 3rd from front, 1-4 is on the passenger side, 5-8 is on the drivers side

 

BTT

I just had this problem occur to me this morning. My truck sat for 5-6 days and a huge storm rolled through last weekend and now it's missing bad. It bucks and jerks driving at any speed. I had the CEL checked and it's #7 cylinder misfire and an emissions code (possibly O2 sensor?). Assuming you're right and the guy at autozone, then it is in fact the 3rd COP from the front on the driver side. I'm gonna tackle this on Sunday. I recently changed all the plugs so I know what fun it can be!

 

the emission code I guessing is a lean code? is probabaly due to the miss not a faulty o2 sensor

 

Well after I bought the COP from Autozone it just randomly went away and now it runs just fine. I still have a CEL on but it no longer misses or stumbles when I drive it and all the power is back. Maybe I just had some water on top of the plug?!

Should I still change the COP? I think I have some bad O2 sensors because I've had a CEL on for awhile now and it runs fine.

 

See what code is in there and service that code. There are a lot of emission codes that can trigger the CEL and the truck will run fine.

 

I had this samething happen to me last week but it would only do it really if I let off the gas then hit it again or going over 60. Well 2 weeks ago I got the sparkplugs changed. Then a few days later it started to run like crap. Then it ran fine then it didnt. Well that P0307 code came up so I took it back to the guy that changed the plugs. He changed the coil and still nothing. He referred me to another guy and that guy said it was the fuel injector. Both mechanics said it was spark knocking and I only noticed it once it would misfire. The second guy said it was starving for fuel and said 1 fuel injector needed to be replaced. It seems to be running good now. Just got it back today and it cost me 200.

I did notice though a few months ago that there was some soot in the exhaust tips and maybe it was burning rich then it started to lean out with the new plugs.