bjcntrygrl

Forgive me for my ignorance when it comes to this stuff but here goes... I just bought a 2000 F150 4 door 4x4 with a V8 4.6L last week (used with 200,000 miles on it) and it all of a sudden has started running like crap. It started skipping or misfiring. Took it to garage and they said it was misfiring on 2, 6 and 8 and also gave a code for an oxygen sensor and catalytic converter. I had my husband change all 8 spark plugs to new motorcraft plugs. It is still misfiring just as bad. I know it could be the coils for those three cylinders too so we are changing those tomorrow. But, any other ideas before we go broke replacing a lot of stuff that we don't need to if still doing it after changing those three coils? Frustrated cause I love my new truck! Just sold my '86 F20 club cab with a 460 engine in it to get this truck and never had this kind of problems with my "old faithful". Please help!

yotermanic

I'm sure this has been checked, but I always like to remind people of the basics, check for vacuum leaks before you hunt random misses. On the 4.6L, the PCV hose that runs along the right (passenger side) valve cover is bad about leaking. It probably is coils but the leak is common enough to spend two minutes checking out.

MT-2500

Welcome one your first post on AF
And welcome to the modern ford tune up.
And yes they could go bad. and sometime 1 or 2 or 3 at a time.
But you can check them before replacing.
Just pull them out of the hole and plug them back up and see if the have good hot blue spark.
Good luck MT.

__________________
Remember proper testing gives us the answer to many problems.
MT

bjcntrygrl

Okay, I give up. We took it back and had it rescanned and it still says misfire on 6 and 8 and something about catalyst deficiency threshold or something like that. One person said to replace the catalytic converter, so we went this morning and had that checked at the garage and he said that wasn't it, that the motor was no good!! What??? The codes that it is giving us is P0430, P0306 and P0308. We already replaced all 8 spark plugs to motorcraft plugs and put new coils on cylinders 2, 6 and 8. I gave in and called the Ford dealership. I have an appointment for Wed morning. Its only going to cost me $37 to $73 to tell me what's wrong with it and how much its going to cost to fix it. ONLY!!! Who cares, right. Money is only Money!

MT-2500

The key is proper testing. And yes that does take money.
But well spent if the proper testing is done right and the problem is found..
If it is missing that will give you a cat code.
Find the miss and that should take care of the cat problem.
Good luck and let us know how it goes.
MT

__________________
Remember proper testing gives us the answer to many problems.
MT

papiichuulo

What was it afterall??