P0301 code

Hello,

Direct Trouble Code [DTC] P0301 is a code for cylinder 1 misfire. If your RPM's are at 3,000 while your vehicle is at an idle, then I would recommend checking your air intake tract, throttle body, intake manifold, vacuum and EVAP lines for a vacuum leak. Here is a link below to a generic guide on how to find a vacuum leak:

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

High or "searching" RPM's at an idle are usually a sign of a vacuum leak. Please pay special attention to the intake manifold portion of the guide. Please go through this guide and get back to us with what you are able to find out.

Thanks,
Alex
2CarPros

Hi,

The code indicated a cylinder 1 misfire. The first thing I would suggest is to inspect the plug wires as well as the spark plugs, specifically, cylinder 1. If the spark plugs have never been replaced, it's time.

Take a look through this link. It discusses the most common causes of a cylinder misfire.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Let me know if the plugs and wires have ever been replaced.

Take care,

Joe

Hi,

Since you have replaced the ignition components, have you checked to confirm there are no vacuum leaks? If there are none, have you checked fuel pump pressure to make sure it isn't too high or low?

If you have and everything is good, then either we have a timing issue (unlikely), a fuel injector issue, or a compression issue (unlikely based on mileage unless it has had a tough life).

With that, here is what I suggest. if you have access to a live data scanner, connect it and start the engine. Let me know what the short and long term fuel trims are (STFT / LTFT). If you do not have access to a scanner, we need to check the following.

The easiest thing is to check engine compression. Here is a link that explains how it is done:

https://www.2carpros.com/articles/how-to-test-engine-compression

If compression is good and no more than 10% difference between the lowest and highest readings, we need to check the injector in that cylinder. The bad part is the upper intake manifold needs removed to access the injectors.

Here is a link that shows how to test a fuel injector:

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

What I usually do is switch the injector of the bad cylinder with one that is not giving a code. In this case, I would switch cyl 1 and 3 to see if the misfire changes to the number 3 cylinder.

Here are directions for removing the injectors. The attached pictures correlate with the directions. When you reinstall the injectors, I always use a small amount of Vaseline on the o-ring to prevent damage to it.

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2001 Ford Truck Ranger 2WD V6-3.0L VIN U
Procedures
Vehicle Powertrain Management Fuel Delivery and Air Induction Fuel Injector Service and Repair Procedures
PROCEDURES
REMOVAL
1. Disconnect the battery ground cable.
2. Remove the upper intake manifold.

pic 1

3. Disconnect the engine control sensor wiring from the fuel injectors.
4. Relieve the fuel pressure.

pic 2

5. Disconnect the fuel line.

pic 3

6. Disconnect the vacuum line.

pic 4

7. Remove the fuel injection supply manifold.
Remove the four bolts.
Remove the fuel injection supply manifold and the fuel injectors as an assembly.

pic 5

8. Remove the fuel injectors.

INSTALLATION

pic 6

1. Install the fuel injectors.

pic 7

2. Install the fuel injection supply manifold.

pic 8

3. Connect the vacuum line.

pic 9

4. Connect the fuel line.

pic 10

5. Connect the engine control sensor wiring to the fuel injectors.
6. Install the upper intake manifold.
7. Connect the battery ground cable.

______________________________

Let me know what you find or if you have other questions, let me know.

Joe