Misfiring

JOE SMITH4

MEMBER
2001 FORD EXPLORER SPORT TRAC
4.0L
V6
2WD
AUTOMATIC
167,000 MILES

SUV sat up for about four years. Recently decided to get it running again(initial problem was fuel pump) I’ve had it running for about a month now. I replaced the fuel pump, fuel filter to begin with (besides the basics, ie oil change, air filter new tires, new brakes.) Everything was fine until about a week ago, no problems. Well it started misfiring and losing power and eventually stalling out, but no check engine or any code lights. So I replaced the spark plugs and wires to start, no luck still same issue. Decided to try a new coil pack. Nope. Also tried some fuel treatment just in case maybe the tank had some left over buildup after sitting so long. Have ran through 2 fill ups and still nothing. Replaced the mass air flow Sensor today and immediately tried it out on the high way and gunned it. Ran smooth, felt like everything was great. Went and had lunch, heading back to work, about 5 minutes into my drive what do you know, same problem. I need help!

2 Replies

JACOBANDNICKOLAS

MECHANIC
109,867 POSTS

Welcome back:

Since there is no code, my first suspect is the crankshaft position sensor. The a bad sensor may or may not set a code. Take a look through these links.

_________________________________

https://www.2carpros.com/articles/how-a-crank-shaft-angle-sensor-works

https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

If you find that is the issue, here is a link which explains how in general one is replaced.

Next, here are the directions specific to your vehicle. The attached picture correlates with the directions. Note that picture 1 is location and picture 2 is provided as a guide when replacing.

____________________

PROCEDURES
REMOVAL

picture 2

1. Remove the Crankshaft Position (CKP) sensor.
1 Disconnect the electrical connector.
2 Remove the bolts.
3 Remove the sensor.

INSTALLATION
1. To install, reverse the removal procedure.

NOTE:
The new CKP sensor needs to be touching the damper. The new sensor has wear tabs that will wear off after several engine revolutions.
Be sure the sensor wiring is routed away from the battery cable.

_______________________________

Let me know if this helps or if you have other questions.

Joe

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Wednesday, May 15th, 2019 AT 7:45 PM

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello,

This could be a vacuum leak problem. If your vehicle develops a vacuum leak it will exhibit all the symptoms that you have described. Visually inspect all of your vehicle's vacuum lines and air inlet tube for loose, misaligned, are cracked parts. Also inspect the intake manifold for gasket deterioration. Next inspect the EVAP hoses for the same thing. I have also included a link for you to go to down below:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Please go through the guide and get back to us with what you are able to find out.

Thanks,
Alex
2CarPros

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Wednesday, May 15th, 2019 AT 7:58 PM

Misfiring

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