I Have An 06 5.4. During Heavy Acceleration Passing Gear It Misses / Hesitates. I Have Changed Plugs ,coil Packs ,fuel Filter. The Engine Lights Flashes Sometime And It Will Have A Miss For Seconds After That,it Will Go Back Fine. I Believe The Flashes Was 20 Pause Then 8 Or 9. Could It Be The Tranny?

 

You need to go over to Autozone or Advance and get the codes read, post them here with the exact P-numbers.

 

Hooked It Up To Computer It Showed No Codes. Any Suggestions?

 

A flashing light is dedicated to a misfire situation. Try to repeat the misfire and get the light to flash again . Sometimes it has to happen twice to store a fault code.

BTW - You have a COP (Coil Over Plug) system. Not a Coil Pack ignition - There different systems entirely.

 

Was the computer CAN-capable?

 

It probably set a pending DTC which may not have been able to have been read by the Autozone scan tool. The OBD II mode 6 data will have all the misfire events stored in it as well. Are you still under warranty?

 

Had the same thing happen on my 99 f-150. It was the brand of plugs the stupid shop put champion plugs in it and you are supposed to use motorcraft. So hope your using ford plugs.

 

Truck Is Out Of Warranty. Had 2 Different Scanners Hooked To It So Far No Codes.

 

Like I said , try to get to misfire again and hold it there until the monitor picks it up and you get a blinking light again. I understood it as a blinking light is code pending and when it stops - code set.. BUT , I've had the same problem - in a older model, a 98 5.4L . I had a blinking light and had it scanned - No freakin code was set.. I went out and gave it hell again until I got it to misfire and held it there until the monitor picked it up again and I got the blinking light. I scanned again and THIS TIME a code was set pinpointing the problematic cylinder.

So try that again.

Other than that , you can get the coils stress tested @ the dealership and/or mode six'ed- cylinder history report.

If I had your 5.4L (3 Valve) and had this problem, I may just order a set of MotoBlue 3 valve COP's for it from RPM outlet. It's just about the same price to do that as it is to have the dealership do the diagnostic and replace the faulty Coil.

 

I Have The Motoblue From Rpm Already.

 

I Ran Truck With Computer Hooked Up. It Showed A Misfire On # 8. The Second Time Random Misfire. A Guy At Another Shop Said He Had The Same Problem With A Ford . It Was A Rocker Bearing Hanging Up .fix It No More Misfire

 

You probably have a defective coil. I have Motoblues installed them and one failed (oddly enough it was also in #8) Get another one or switch the coil out of #8 to # 1 and see if the missfire moves with it.

 

Well I Finally Got It The Misfire During Heavy Acceleration Fix. I Changed The Plugs Again And That Fixed It.thanks For The Input.