2000 F150 mis-fire between 1500-2000 RPM


#1

i have a 2000 Ford F150 with a 4.6 Triton. engine has 125k miles on it and has been perfect all this time…seems like i just replaced my alternator prior to my problem… my problem is that when running stable between 1500 and 2000 rpm the complete ignition will shut down and the truck will buck and jerk. i can throttle through this range fine, but when stabilized it acts up. i have replaced ever electrical sensor on it. crankshaft,camshaft,throttle,MAF,all 8 plugs and all 8 coils and a brand new alternator. the shop has replaced the computer and still this truck acts up ONLY between those rpm ranges. Ford said maybe the thrust washer behind main crank bearing was worn and allowing the crank to have to much play, thus allowing crankshaft sensor to loose timing ring/wheel. the shop check crankshaft end play and said it seemed ok. they are thinking that maybe some how the crankshaft timing wheel/ring is becoming maginatized. the shop said PIP signal is kind of distorted… not as crisp as they would like…i get a p0320 code which is engine/ignition speed input circuit failure. i have put a remote start on it, but it has been on for a year before this problem started. just to make sure not crankshaft sensor i replaced it again, same problem.


#2

[b]The problem might be with the Vehicle Speed Sensor.

Your vehicle has two VSS’s. One is for the speedometer input signal and the other is for engine management input signal. Because the the engine management system requires vehicle speed input in order to adjust the timing for ignition and fuel injection, it sounds like the VSS for the engine management system is the one that’s defective.

Tester[/b]


#3

could this VSS effect vehicle even if car is in park? i can rev it up to 1500 rpm and it will start missing out


#4

FIXED it. i replaced the crankshaft sensor wires. ran 2 new wires from the crankshaft sensor to the pcm on the firewall behind battery… pin’s 21 and 22 on main computer connection. 150 miles and no miss at all.