I was driving my truck to work this morning and my check engine light came on. I drove about 30 miles last night no problem. I noticed the check engine light flashing, and then it kinda seemed a bit sluggish. its a 97 F150 4.6L 138K had new plugs, and wires about 20K ago. New K&N CAI a few weeks ago. Any suggestions on what to check?

 

i used to have a similar problem with my 97 explorer. it kept on burning up spark plugs for some reason. if you have the truck scanned, it will tell you what cylinder is out. then it could either be just the plug, or an injector, or a coil. i would suggest starting with the cheapest problem and replace the plug. good luck

 

Easier to change them all out -

Lookup "Misfire" in this forum to find great COP & coil links (I made it easier)

 

Get the code(s) FIRST.

Otherwise, you might as well pi$$ into a hurricane.

Steve

 

code P0302 cylinder 2 misfire....






I put a new plug in cylinder #2 still no fix. took coil box out had checked at murrays. Checked OK. Checked spark plug wire came out fine with resistance. Even though the wire checked fine it was bad, checked by swaping another cylinder wire, and that cylinder started throwing codes. Replaced wires and problem went away. Replaced all the wires AGAIN with motorcraft wires. Old wires were replaced last february, and under Motorcraft warranty I got new ones free. Thanks for the help

 

well Im a liar. Drove about 100 miles today, and check engine light came on and truck started vibrating again. Ran the code P0304 cylinder #4 is now misfiring. Bought some injector cleaner, and dry gas ran it through it, but still not any better. I went to Napa to buy a fuel filter cuz I thought that might have been the problem, but the guy at Napa felt pretty confident that it was either the Coil pack, or the DPFE sensor. I already checked the Coil pack at Murrays and it tested OK. I find it odd that before I put new wires on that all the codes came back to P0302 Cylinder #2 misfire, and now that I put the new wires on the code I get is P0304 Cylinder #4 misfire. Anyone have any ideas on what I should do?

 

Like I said "Easier to change them all out" - Keep that hurricane on your backside...

Take into consideration your milage, you would do it a world of good to change them out anyway.

Good Luck

 

The blinking CEL is an intermittant code that isn't fully setting off. It could be a random multiple misfire. Get one new coil pack. Start with number 1 COP and replace it. If it still runs chitty, use that one you replaced on #2. and so forth until it stops running chitty, then you only have to buy one COP

Inherently, it will be the last one you check, no matter which one you check last

 

lol - just replace , there spent , they had a long life..

It's and integrity issue with coils , specially high milage ones. I wouldn't mix old with new with this ignition system. I've seen the multiple misfire code many times - too many!! not just my truck.

Most common load failure 45-55mph , D to OD after shift..

 

Update:

After hearing rumors of heater cores leaking onto cylinder #4 I inspected the heater core lines, and didnt see any leaks. I pulled #4 plug wire off inspected it, put some dielectric grease on it, pulled the hoses off from the DPFE sensor, and put more dielectric grease on the coil pack. It now seems to be fine for this minute. I went ahead and bought a coil pack and am awaiting to see if I throw another code again, then I will replace coil pack.

 

i might have another thoery for you too. i have heard of this happening before. Sometimes your harmonic balancer will go bad, it will vibrate and it can throw off the timing and make you misfire. Pretty easy to check the balancer, i would definitly give it a try.

 

also might wanna look into a grounding wire kit it will help the life of the coil packs.. ford has one of the worst grounding systems .. so just make ur own grounding kit or get one off ebay for 15 bucks or so they are well worth it.