Not me, the truck! Anyway, I have a 1999 Expedition 4x4 with 136,000 miles on it. It has a 4.6l vin 6 motor, non-COPS no mods. I recently gave it a tune up and some fluid changes. I replaced the plugs with Autolite double-plats and Autolite 8mm Professional Fit wires. I changed the air filter, fuel filter, PVC valve, front diff grease and the transfer case fluid, trans and rear diff TBD in the next week. I ran it hard for a week to see if any issues popped up and it ran like a champ. Now the problem.... about 2 hours into our 4 ½ hour trip, the truck starts acting funny.




At 70 mph, it seemed to start missing every once in awhile. Then it got really bad when we went uphill on the overpasses. The engine light came on steady. It seemed to stumble on gently acceleration, then when I stomped it, it took off. The engine light would flash about once a second during this steady acceleration, then go back to steady when we settle down to 70. It settled down at 70 this started all over again. Then it got bad at 70 mph, I slowed it down to 65 and it ran fine, until I accelerate. Accelerate slowly, it stumbles and feels like it is going to shake the motor apart, accelerate hard and it takes off with some stumbling, but very slight.




I have very limited resources where I'm at. I cannot pull the codes, but I am going to look at the fuel filter (did I put it in the right way?) and the intake area. I checked the wire, plugs and coil packs and everything looks 100%. One of my buddies said it is the injectors and another on said it is my MAF or throttle body.




Any educated ideas??? I really need some help as I have to make the return trip with a very sick truck.

 

Well, I finally got the truck home. It really missed bad at low speed and up to about 2,000 RPM. It seemed to smooth out around 2,500 RPM and as long as I kept the OD off during the trip, it ran okay.

When we got home I pulled the codes and got P1131 and P0306. This leads me to beleive that it is the plug (#6) or injector. Could it be the coil pack? I DO NOT have COPS.

Any help would be appreciated.... Thanks in advance!