buckeye

hello:
My 98 f150 with a 4.6 has been giving me fits for a couple months now. It will start and idle but with a miss. It runs fine at low speed (up to like 20 mph) but when i accelerate or try to go up an incline it looses all power and has nothing. It doesnt die, its just like i have no pedal. Then after a while it will gain some power back...sometimes.

I have replaced the fuel pump, fuel filter, plugs, wires, one coil pack and the other was tested and fine, the #2 injector (as the code given was on the #2 cylender originally and the mechanic couldnt find anything wrong).

Im thinking it may be the catalytic converter, but when we checked vacume pressure it seemed fine...staying around 20 pounds.

any advice...please!

torkum

It does sound like a catalytic converter stopping up. You should be getting a code if the converter is the problem. Have you put a scanner on the truck and monitored the O2s?

Lenn

Why don't you just unbolt it and run for a few miles open exhaust and see if the problem is corrected. If you have the ability to scan for codes, than more power to ya. It seems easier to just take it out and do a dry run.

Also, what about a MAF/MAP sensor on the fritz causing it to flood/richen it out? IDK, I'm just throwing out ideas.

buckeye

yeah tork, the mechanic was getting a o2 code when it was in the shop, so maybe i should try the dry run just to narrow it down. Thanks both of you!!!

mawk

Check the EGR valve while you're at it. Give it a good cleaning.

torkum

Running with no cat will set a O2 code for the down stream sensor, just erase it when your hooked back up.