I have a 2001 4.6l with 179,000. Getting up there!! Last year in September it started to misfire so I scanned the codes and found a misfire on the 4th, and 8th cylinder. Also a bank 1 too lean. So I changed the plugs, and greased the COPS. Now just a few days ago it started to stutter and misfire like before. Not all the time though. Mostly under load. Slight uphill before it down shifts. If im cruising or getting on it, its fine. I took it to advance auto to read the codes and it would could not connect to the truck. Thinking maybe the reader was bad I went up the road to another advance auto and same thing. Im not sure where to go from here. I dont know if I should just replace the coils, since its probably well due. Im confused as to why the code reader wont connect to the truck though, last time no problems. Any help would be great.

 

Change your cigarette lighter fuse and they will be able to read the codes. You most likely have a bad cop or plug. What plugs did you use last year?

 

Do you mean the reader physically wouldn't connect to the truck or electronically wouldn't read? If electronically, maybe try disconnecting the battery and resetting the PCM and see if you can get a read.

If you have a low grade misfire, it most likely won't throw a code anyway. Did you change ALL the plugs a year ago? If you only greased the COP's and didn't replace them, I'd spend the $80 or so and get a set of new ones from Uneek or Global Auto on ebay. As long as you're at it, pull the plugs and see how they look. If you used anything other than Motorcraft, NGK or Denso's, invest in one of those brands. As I've found, low grade misfire's are a pain to find.

 

I used Motorcraft plugs when I changed them. My cig lighter still works, I charged my cell phone on the way home today? Should I still change it and try that? I mean it electronically wont connect, the plug fits fine, but it says "trying to connect to......" then gives me an error message and says to try again. I tried it a bunch of times, no luck. Is there a certain amount of time I need to leave the battery unhooked for?

 

sounds like you have a bad COP

 

the fuse for the OBD port is bad. replace and you can read.

id replace all 8 COP go on ebay global sells them 100 bucks for a set of 8 everyone on here loves them with no probs.

 

So I replaced the fuse for the cig lighter, data link connector and remote entry module. A 20A fuse, even though the one that was in there wasn't blown. Then went to try it again, still the same result. Error, can not connect. I also tried unhooking my battery for about an hour to reset the PCM, my CEL went out from that and hasn't come back on since. But didn't help my code reading issues. I checked the wiring behind the harness and it looks good, no corrosion on the plug itself either. Im nor sure if my misfiring problem has gone away or not but yesterday afternoon I changed my oil and while I was in there I cleaned my IAC and MAF, like to do that every other oil change or so and on my drive home no misfiring!!! So I drove home then back to work this morning, about 50 miles, no CEL and no misfire. Im still going to change the COPS but Im more baffled at why the code reader still wont connect to the truck?????

 

huh wonder what it is try autozone and see if theres works?

you prob had a bunch of crap on your MAF wires. truck didnt know how much air was coming in so it guessed with the fuel. your truck was running in open loop. you cleaned the MAF now it can go Closed loop and knows how much air is coming in.

still recommend the COP from global.