BigBlue2003

Hello fellow f150 owners, I own a 2003 f150 4.6l V8 and ive owned it for about 6 months now. i bought it with 190,000k on it and within the week of purchase i repainted it true blue with flake, replaced the entire front suspension, lifted it 4" and added 33" BFG Ko2s and it turned out gorgeous and for the first 4 months i never had a problem. one day it was running a little dirty while going up a hill and i decided to change the spark plugs to clean up the engine a little bit. the job took a little over 2 hours because i wasn't familiar with ford engines and the old plugs were rotted and corroded to a level ive never seen before. after changing the plugs the truck ran great for about a day and then a check engine light came on. I put a reader on it and it came up insufficient EGR flow. not knowing what it was i disregarded it and continued on, only to feel a full engine misfire the day later. i cleaned and made sure the EGR was clean and running sufficiently again and went on my way. 1 month went by and on a rainy day the truck began to misfire again, with no check engine light on (heres where hell begins). i took off the coil packs and blew out the plug holes and found water in 2 cylinders. i then blew out the cylinders dry and removed the plugs to make sure the water didn't go deeper and i was safe. i replaced all the boots and metal springs to make sure this wouldn't happen again. 2 DAYS went by and the engine started to kick again, but this was weird. it would only kick at either idle, or in 4th gear at low RPMs and it seems like its only 1 cylinder. i replaced coil packs and clips from the wiring harness which had imperfections and now i cant figure out what else to do. if anyone has any help to offer id be very grateful. i love my truck and want it running clean again.

jstockert

What brand plugs did you use?

BigBlue2003

Ngx iridium

techrep

iTrader: (1)

with 190K miles on her...I would replace all the COP's

BigBlue2003

I replaced ones that I found with cracks on them or other imperfections and Attached a multimeter to the rest to make sure they were giving out adequate power and they were all giving me the same reading

Ford Fan#1

The 5.4 and 4.6 like the motorcraft plugs and ignition coils. If you don't use ford parts on the motor then it tends to miss. Some people have had good luck with the aftermarket stuff. But personally I would use parts from tasca parts. Visteon coils work too.

screamineagle

This^^^. Motorcraft is the only plug for these engines. I learned the hard way!

Mr. Beef Gravy

x's 3. The auto parts stores like to upsell you plugs but these engines hate the iridium plugs.

Frank_Ford

I second that with motorcraft plugs. I have found that a lot of the other aftermarket plugs work loose and will start missing. Your miss should be throwing a code that will tell you the cylinder that is missing. start with the cylinders that are missing and make sure the plug is tight, the cop connection is clean. I like to use permatex di-electric grease on all the connections. It only cost a couple of dollars at autozone or others. Your water problem could be a leak in your manifold.

jprevat

iTrader: (1)

I have been running mc iridium plugs with no problem for years.