Truck is a 99 f250 v10 5sp 4wd

I just bought it, and im ready to burn it intermitent missfire under power only. I figured it was in need of a tune up (after hours of research here) so today I;

replaced boots
changed plugs (autolite double plat. 103's)
switched cop's around
cleaned maf
cleaned iac
cleaned throttle body
new air filter
new fuel filter
new pcv
new tps
replaced any vac lines in question

It runs better but still has a hard miss under power and falls on its face after 3k rpms. I thought maybe a cop was going bad so I bought a actron 9180 to scan for pending codes and it shows nothing. I had the batt unhooked while working today so maybe that cleared the pcm of codes and I havent driven it enough to throw new ones? I put 10hrs and 300.00 in this thing today and its still doing it! I cannot afford to keep throwing parts at it or take it to someone else to do the same @ 60.00+ per hr.

Any help would be greatly appreciated, I have to get it fixed.

 

fuel pump ???

 

Ive considered that. Any way to know for sure? @ 200-300.00 I hate to just throw parts at it. When I changed the fuel filter I did expect more psi than it had on it.....

 

Im going to pick up a fuel pressure tester today to check fuel system. Still havent ruled out bad cop's yet either.

For referance it had no cat converter and a flowmaster muffler on it when I bought it. Shortly after purchase it threw a "insuf. egr flow" code. I put a universal 3" cat and a universal 3" muffler on it and code has not returned. Its seems this miss has gotten worse though. ??????????????????????????

 

I have had many modular motors and 99.99999 % of the time it is the cops .go on ebay they are $ 100 for 10 of them coat the boots inside and out with dielectric grease and your problems should be gone

 

My '99 had a similar issue. I was certain it was a bad COP even though there were no codes. I bought new boots for all the plugs and used the dielectric grease on the install. I still had the problem but in retrospect, I think I cured what caused the misfire, but not the result of the problem. Water had gotten down the plughole (due to cracked boots) and shorted out and ruined 2 COPs. Visually I couldn't tell which was bad so I purchased 2 COPs. I started in the front of the engine and replaced the COPs one at a time. As the miss only appeared under load, I installed the new COP and then went for a ride. If the miss didn't go away, I reinstalled the old COP and moved onto the next one using the new COP. On the second try, my miss smoothed out somewhat but was still there. After changing that COP, I moved onto the next using my second new COP. On the 7th changeout, the miss smoothed out and went away. It was a huge pain to install the new COP, hook everything back up and then go for a ride. Then reinstall the confirmed good COP, and move on to the next one. But my V10 now runs great and I've had no problems for the last year. Old plug boots that go bad hold water against the COP which sometimes kills the COP. Using the dielectric grease just aids disassembly for the next time as well as an extra measure to keep water away from the Plug and COP.

 

On ebay you get all 10 cops with boots and springs for around $100.00 . I have been using them for years with great results I load the heck out of them inside and out with dielectric. It is a good idea to use dielectric in everyplace you can on fords in my opinion .I just had my transmission acting all scewey when I took all the electrical connections off the trans they were either full of water or they were very damp and dielectric grease on all the plugs made my transmission like new again

 

I would get the ebay coils but I cant wait the 2 weeks for shipping. It threw the "insuf egr" code on the way home so I stopped and bought the egr valve, dpfe, and vac sel. (175.00 ) I dont think thats what it is though...just needed to be done. Im about to bite the bullet and and replace all 10 COP's. I have to have this truck going asap, its our primary vehical as of now. It really sucks the 150.00 scanner I just bought doesnt tell me crap!

 

I think you have to have a pretty bad misfire for it to show up on those scanners. I have a $300 mac/craftsman scanner and they do not show up on there.Good luck I hope you get it resolved quick

 

Great write-up.

COP has always been the issue on the 4.6. I was doing some research when we first got it and learned as PM replacing all at 40K miles was the idea solution. The Ford dealer gets like $50 each I think.

Sounds like the $100 E-Bay solution is a good way to go maybe.

 

Yeah mine started going at 53k on my harley truck and around 75k on my x

 

I did the cop's, 442.35 worth ;( O.E. replacments with a 1yr warr. The missfire is gone but it still falls on its face @3k rpms. im really at a loss and dissapointed in the truck at this point. Starting to wish I had gone with a OBS powerstroke truck

 

Check the intake manifold gasket. That's what's causing the problem on mine, which is waiting for a new gasket!

 

Its running great today. It runs as good as our '07 f650 proloader w/ the 6.0psd/allison combo. Its still not to impressive above 3500rpm but I found I really didnt need it for DDing anyway. Ill check that gasket, and plan to put a fuel pressure tester on it too then report back. Thanks for the help

 

i'd hook up a vacume gauge aswell while taking her for a spin see what she says before digging in for an intake gasket...