Misfire at low RPMs?

Hi,

The first thing to do is have the computer scanned for diagnostic trouble codes. This way, we will know if it is one or more cylinders and which ones are causing the misfire.

Here is a link that explains how to scan for codes:

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Next, when was the vehicle's last tune-up? Has anything been done recently that may have caused this to happen? Does the check engine light stay on solid or flash while driving?

Let me know as much as you can. I mentioned scanning the computer. If you don't have a scan tool, most parts stores will scan it for you free of charge. Have it done and let me know what codes are stored.

Additionally, take a look through this link and let me know if it helps:

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

Take care,

Joe

Hi,

Next, check to see if there are any engine vacuum leaks. That can cause issues.

Here is a link that explains how it's done:

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

Also, if you have a live data scan tool, let me know what the short-term fuel trims are with the engine at operating temperature.

Take a look through this link as well, you may find it helpful:

https://www.2carpros.com/articles/automotive-engine-misfire-code-p0300-causes-and-solutions

Let me know.

Joe

Hi,

If sensor 2 is at 99.2%, either we have low fuel pressure, a rather large vacuum leak, or the sensor is faulty.

Since you have a live data scan tool, watch the voltage signals from B1S2. It should adjust itself between 0.1 and 1.0V. If you notice no change in the voltage, replace the sensor. It is the likely issue. However, also confirm there isn't a wiring or connector issue.

Let me know what I can do to help.

Joe

See pics below. Note: B1S2 is after the catalytic converter. I attached pics showing both sensors. The air/fuel sensor is sensor 1 (pic 1). The heated O2 sensor is in pic 2 below.

Hi,

I watched the video. The STFT shows 99.2%. That usually indicates the fuel trim isn't being used. Was the engine at operating temperature?

The voltages are within spec for sensor 2. Sensor 1 is higher than expected, but if the vehicle was cold, that could be a reflection of a rich air/fuel mixture.

Let me know.

Joe

Hi,

Normally, the voltages should range between 0.1 and 1.0v. However, although 3v is high, it isn't uncommon. Especially if the engine is cold. That's why I asked.

As far as testing is concerned, the manufacturer doesn't provide a voltage reference point. Instead, they want you to check the resistance in the sensor itself.

I attached those directions below.

Let me know.

Joe

See pics below. I never confirmed if this is a 1.8L or a 2.0L. Also, the information provided below is bank 1 sensor 1. Your crazy readings are for sensor 2. Confirm the engine size for me.