JustAnotherMember7
Active Member
- Joined
- May 12, 2020
- Messages
- 57
- Reaction score
- 19
- City, State
- Twin Falls
- Year, Model & Trim Level
- 2001 Explorer XLS
I am having problems with what seems to be an engine misfire on my 4.0 SOHC from late may to the end of july the last few years I've had the car.
I can run air conditioning just fine but the engine will randomly start shuddering at idle (dips down to 400RPM), moderately reduced acceleration, may run rough at higher RPM, and the problem will randomly start and stop on a cold and warm engine. It starts one day, and can "magically go away" a day later, or a month later. (These symptoms usually start towards the end of may and can not be recreated consistently, only about 50% of the time, and problems usually persist until the end of july).
Turning the air conditioning system off *sometimes* will help reduce shuddering, but the above-mentioned problems have a 90% chance of continuing even after A/C is turned off (completely off, not just to vent and floor which seems to be a A/C "hybrid mode").
Although I can run the A/C all I want in April, most of May, August-October and not have ANY of these problems. This has been a reoccuring problem the last 3 years, during the same months, same symptoms, goes away as quickly as the problem shows up.
Here is what has been done the last few years I have owned the vehicle in terms of repair
Jan-May 2019
My current plan is to remove spark plug wires, coat them with some dielectric grease, inspect spark plug porcelain, inspect spark plugs, measure resistance of spark plug wires, remove and reconnect the computer wire harness, and remove and reconnect the main engine wire harness connector (large square-shaped, on left side of engine).
What in the ever living world could be going on? I plan on ordering the OBD-2 adapter so I can use forscan and check EVERYTHING but am at a loss as to what is going on.
I can run air conditioning just fine but the engine will randomly start shuddering at idle (dips down to 400RPM), moderately reduced acceleration, may run rough at higher RPM, and the problem will randomly start and stop on a cold and warm engine. It starts one day, and can "magically go away" a day later, or a month later. (These symptoms usually start towards the end of may and can not be recreated consistently, only about 50% of the time, and problems usually persist until the end of july).
Turning the air conditioning system off *sometimes* will help reduce shuddering, but the above-mentioned problems have a 90% chance of continuing even after A/C is turned off (completely off, not just to vent and floor which seems to be a A/C "hybrid mode").
Although I can run the A/C all I want in April, most of May, August-October and not have ANY of these problems. This has been a reoccuring problem the last 3 years, during the same months, same symptoms, goes away as quickly as the problem shows up.
Here is what has been done the last few years I have owned the vehicle in terms of repair
Jan-May 2019
- 1st Engine replaced with a 2nd engine pulled from a different explorer (timing chain componenets looked good, no other wear problems noticed).
- New spark plugs installed
- Wiring Harness COMPLETELY rebuilt and covered
- All fluids changed
- All filters changed
- Conventional oil used, later changed out with full synthetic (based on E.F. posts)
- Spark plug wires tested
- New battery
- New fuel pump
- New fuel filter
- New tires (pulled from boneyard cars)
- tires mounted and balanced
- Sway bar bushings and end links replaced
- R 134-a added to A/C system
- Front and rear shocks changed
- Oil changed 2020
- Fluids topped off 2020
- Safety inspection performed 2020
- Oil changed 2021
- Battery corrosion cleaned from terminals2021
- Positive battery post loose wire fixed 2021
- Upper control arms changed 2021
- Lower ball joints changed 2021
- Front wheel bearings replaced 2021
- Rear Wheel bearings replaced 2021
- Rear wheel seal replaced 2021
- Rear diff. oil changed 2021
- New brake pads (front and rear) 2021
- New brake rotors (front and rear) 2021
- 2 wheel Thrust alignment performed 2021
My current plan is to remove spark plug wires, coat them with some dielectric grease, inspect spark plug porcelain, inspect spark plugs, measure resistance of spark plug wires, remove and reconnect the computer wire harness, and remove and reconnect the main engine wire harness connector (large square-shaped, on left side of engine).
What in the ever living world could be going on? I plan on ordering the OBD-2 adapter so I can use forscan and check EVERYTHING but am at a loss as to what is going on.