I have a 2001 F-150 4.6 V8 with 118000 miles on it and I am in need of some help. In December i was running about 4000 rpms and the engine began to misfire real bad. So i stopped at the nearest gas station and checked the coils and everything else. Got back in and it ran fine. The following week i was at the same place running 4000 rpms and it started misfiring again. Stopped at the same gas station pulled the wires and check my injectors. Got back in and it never fixed itself. So i pulled all the plugs and changed them. Still missing. Then i changed all my coils. Still missing. Then i changed my fuel injectors. You guessed it, still missing. So i took it to autozone and ran a test on it. Still had a misfire in cylinder 2 and 5. After running some more tests on it i found out that i have zero compression in those two cylinders so i pulled the heads. Come to find out the lash adjusters were pumped up in both cylinders, holding open the valves. So i changed all 16 lash adjusters and put the engine back together. Started it up and.....its still misfiring. So i took the valve covers off and took the springs for compression checks. They passed with flying colors. So its not the lash adjusters, not the springs, not the coils, not the spark plugs, not the fuel injectors. Im out of options guys. Anybody with some help on this i really would appreciate it. Thanks

 

what kind of plugs you running

 

Motorcraft i believe-platinum

 

clean up your iac and egr

 

I took it to Ford and they ran tests on all the electronics. Everything came out fine on that. I dont know why my lifters would keep pumping up though. Its causing the intake valves in both 2 and 5 to stay open. Since i got the truck ive been putting 40w oil in it. When i compress the lifters, it takes a lot of pressure to squeeze out the oil from inside. I was wondering maybe if that is the problem, and if i put in 5w-20 would that be the correct way of fixing the problem?

 

I run 5W50 in mine so it is not the oil. The triton series of engines are interference engines so if the valves stayed open they must have smacked the top of the piston. You most likely have bent some valves.

Regards

Jean Marc Chartier

 

I pulled the heads and had them checked out. There were no signs of damage such as that. Also it seems like the engine surges sometimes with powers so im really confused about that

 

Had a prob similiar on my Bronco, and some co-workers did as well. It was the wires. even though they looked good. Changed em out, no problems since.

 

the 99+ 4.6 has cops like the 5.4 bud. so its not gonna be wire per say, but maybe the cop its self? i know jbrew loves replacing them cops lol

 

replaced all cop's. im out of options. must be oil pressure or something because the tensiors had a great amount of wear on them. they are operated by oil pressure too. we'll see. tomorrow im putting it back together again so if anybody has anymore ideas let me know.

 

Check the oils galleries for obstructions. The lifters vent from the bottom to the crank case. Pull the lash adjusters of the affected cylinders and check the return hole at the bottom if the gallery.

Regards

Jean Marc Chartier

 

The 40 weight could be a problem, The lash adjusters are designed to use 5-30, or 10-30, and that may very by year? If you are trying to bleed them, yes it is hard to do even with 5-30.

 

No obstructions in the oil channels. Putting it back together today and putting the different oil in it. I'll keep you posted.

 

Put the required oil in it, the modulars are very picky with the oil you run. Had a guy who ran 40w in his 04 cobra, it was always kicking the adjusters off, went to the 5w-20 and smooth ever since.

 

Well. I put the correct oil in it. and guess what...Still missing. Took it to another automotive shop and they dont know what to do with it so they sent it to someone else. Could it be a catalatic convertor?