So I have a 97 4.2 that has not given me one day of good running service since I bought it one year ago. Something always goes wrong. I have been battling a major misfire problem for about 5 months and am having no success, please please please help me!!
The misfires seem to come most often under acceleration (but sometimes while cruising)
My OBDII scanner says misfires are on Cyl #1

I have replaced
Coil (OEM... a week ago)
Plug wires (OEM... a week ago)
Plugs (autolite premium 15k km ago)
Rebuilt heads (mine were cracked)
Upper engine gaskets (heads and up) (Viktor)
Exhaust manifold (OEM)
O2 sensor (NTK)

I also have a code saying Bank #2 Catalytic below threshold

Ready to blow this truck up pretty soon... Please help me.
I really do love F150's but this one has it out for me..

 

Did they do a valve job when the heads were off?
Have you checked compression on the cylinder?
Have you check the fuel injector?

 

Thanks for the reply =)
Yes they had a valve job
Yes compression is good
Yes the injector is working properly with 0 faults on my OBDII scanner

 

Any body have any more ideas?? I really need to get this fixed, I love this truck but I cant live with this much more.

 

Welcome to the club! I got mine with 67K miles on it 3 years ago and I've sunk $4000 into engine repairs on a truck I paid $5K for and now have 125K on it. My lower intake manifold cracked at 94K miles, throwout bearing went out at 95K, had to get the PCM reflashed at 104K, lost the slave cylinder at 80K, had a cylinder 1 misfire that was caused by a plug wire shorting out on a valve cover at 75K...I really consider the 4.2 the worst engine to ever be put in a full sized truck.

 

That's nuts you've had all them problems zap I've had mine for like 8 months with 123000 miles and havnt had any problems other than a time up when I first bought the truck

 

Not to mention before the lower intake manifold was replaced it was getting over 18 mpg, now it only gets 14. It has certainly discouraged me from buying another ford half ton ever again. Don't trust the power strokes because I've seen too many of the engines (friend of mine has already blown a 6.7) come apart on the highway. This past year I put 25K miles on the truck in 11 months for college. Least it didn't give may any problems this year seeing I go to school 400 miles from home. Not to mention there has been a slight slap in one of the cylinders since 98K miles.

 

I agree. Any ideas about my misfires?
I am going to change the cats next week with 2 universal magnaflows. Hopefully thats not just another $300 down the drain

 

Plugs, wires, pcm, coils. Check and make sure you have fuel pressure on the injector that feeds that cylinder and that the injector is working. Also pull the plug out of that cylinder and see if it is spitting out gas, anti-freeze or whatever. 4.2's are notorious for having cracked lower intake manifolds and then dumping the coolant into the manifold and cylinders and hydrolocking the engine. I'd say pull the plug first and work up the intake manifold from there.

 

I think I'm just going to give it to the stealership for a day to diagnose. Then will fix what they say it is.
I can't take this chasing down problems anymore.