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1999 to 1998 4.2 engine swap misses / difficult starting
I installed a 1999 4.2 in a 1998 F150. 1999 was an automatic, 1998 is a manual. I am getting a code p0340 Camshaft Position Sensor Circuit Malfunction.
Wire and vacuum harnesses were different, mainly due to the different IMRC. I disconnected a wire in the engine to chassis harness on the engine side that was on a secondary connector, not the main PCM connector. I am getting a code p0340 Camshaft Position Sensor Circuit Malfunction.
The wire I cut is a gray wire with a white stripe, and I am not sure what it does, but it may be the cause of my problem.
The 1998 has a round 4-wire connector, the 1999 has a square 5-wire connector. I cut the 5 wire connector from the 1999 engine and soldered on the round 4-wire connector from the 1998 engine, leaving the gray/white wire not connected.
I tested the intake air temp sensor connector and I am not getting a voltage, it should be 5v. Same with the Cam Position Sensor, no voltage (although on one test a constant 2v was measured). Negative wire on both sensors have continuity with the negative battery terminal.
Trouble codes:
P0340 Camshaft Position Sensor A Circuit (single sensor)
P0113 Intake Air Temperature (IAT) Sensor 1 Circuit High
P0118 Engine Coolant Temperature (ECT) Sensor 1 Circuit High
P0135 O2 Heater Circuit (Bank 1, Sensor 1)
P0155 O2 Heater Circuit (Bank 2, Sensor 1)
The pickup runs like a top if kept in a warm garage. It is difficult to start and runs rough if the engine is cold. I read that the problem may be the PCM.
The gray wire is number 321, connector c119, and in 1999 F150 wiring diagram. One diagram shows it could be for the AC.
I replaced the PCM with a used one with identical part numbers. It started sooner but it was still difficult and idled poorly and set the same codes.
I am going to check all grounds and maybe add some (like I should have done initially).
If anyone has suggestions, I would appreciate hearing them.
The problem turned out to be different pinouts on the C120 plug (main wiring connector from engine harness to chassis harness).
Pins need to be moved on the 1999 engine connector to match the pins on the 1998 chassis connector.
The conflicting pin circuits on the 1999 engine are: 2, 6, 16, 27, 31, 42
Pin 27 on the 1999 connector was the 5v gray wire which I moved to Pin 40 to match the 1998 chassis connector. Now I have 5v to the cam sensor and the pickup starts easy and runs smooth. I still need to check the remaining circuits.
11-03-2023, 03:14 PM
1999 to 1998 4.2 engine swap misses / difficult starting
