I have a 1997 f-150 w/ 5.4 just turned 90,000 miles. I first blew a plug (#2) out and replaced it with a heli coil and new cop and plug. every few months I have misfire on that same plug and have replaced same plug and coil pack with no luck. still does same thing again everyso often. code PO 302 and light blinks and engine bucks. next, check engine stays on so zi checked and it says bank 2 sensor 2 is bad so I relplaced all4 and then all cats because ford said they werent workin. still checkengine light is on. What next? Im runnin on empty with my ford and after just finishing up a divorce, my wallet is also. so I cant afford to get rid of it yet. any help will be greatly appreciated.

 

You have to use dielectric grease at least inside the boot(s) .. I'm guessing you haven't on #2..That's the only thing I can think of that makes sense ..

Good Luck

 

Go to autozone, and have them read the codes. Post ALL the codes here, and we'll get ya fixed up.

 

Don't overlook the injector on that cylinder. It could be hanging up or being restricted. Try swopping COP next time with one from another cylinder to make sure its ok.

 

Codes might be off because my brother has a '97 f150 and it did the same thing, his service engine soon light came on and had it checked many times and nothng was wrong, so check ur codes because codes or sumthnig internally is wrong.

 

codes are as follows: PO302 which is cylinder 2 misfire and PO156 which is bank 2 sensor 2 and I have replaced all 4 sensors and the number 2 plug and cop after the plug blew out of the head. any suggestions?

 

Clear the codes.
Then what drivability problems are there?
How long does it take for the codes to return?
After awhile you have to start all over again fresh on the problem and not keep getting confused with old history.
Your dealer could have looked at the ox sensor operation to first determine their health after replacing the cats.
If they are functioning then the fault is not with them but the signal getting back to the PCM.
Since there is a single cylinder fault, the problem is right there at that point in either the plug, the cop, the boot, the wireing or an injector OR cylinder health. Is the plug fouling, dry etc?
You are at the typical point of trying to fix with mechanical thinking when some in depth is in order.
Translated, you can't rely on just the codes without getting into the total operation, when parts replacement doesn't do it..
Good luck.

 

I have replaced all 4 o2 sensors and the cats (all 4) and the cop and plugs. driveability after and even befor is fine until starts misfiring. park it for a day or two and come back and it runs fine again for a few days and doing nothing to it. One of those ghost problems. cleared codes and takes about 1 or 2 hours of driving befor light comes on again. no changes in sounds or drivability but comes on and stays. when it misfires, it blinks.
its too young to die, only has 90,941 miles on it on a 1997 f150 supercab w/ 5.4
going to replace all 8 spark plugs and cops and injectors i guess next.

 

when it misfires, it blinks.

This suggest the fuel system regulator could be faulty and pressure may be to high.
Check the pressure next.

 

I used to have a '97 F-150 4.6L....... the check engine light came on 30 minutes after I bought the truck (used). I took it back to the dealer that week and they changed out the O2 sensor...... the check engine light came back on within a day. I drove the damn truck for 2 years with the check engine light on because it drove fine. Somewhere in that time frame I had the codes read for an inspection sticker or something and the only code was an EGR valve fault. I never had anything done to it because it still drove fine. Then one day while I was changing my oil I decided to change out my air filter. The check engine light went off and never came back on. I can't explain it.