Shakes and loss of power

If the plugs are soot covered then that would be too much fuel or unburned fuel from poor ignition.

Here is a guide that will get us started even though it appears you have replaced the basics so unfortunately this won't be the easiest of repairs but I am sure we will find it.

https://www.2carpros.com/articles/symptoms-of-low-engine-power

The shaking is most likely a misfire so I am going to think that we have one of a couple issues remaining. First and foremost leaking injectors or fuel pressure issue. So we need ot start with checking the fuel pressure.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

If the pressure is high then that can dump too much fuel. If it is low then it could be leaking injectors.

The next likely issue is the PCM is just commanding the injectors on for too long. Normally it does this due to a faulty sensor but it looks like you replaced the common ones that would cause this.

So how long did it take for these plugs to get fouled?

The last possible cause of soot covered plugs is a timing issue that basically the exhaust valve is opening too soon. So we should check the compression and make sure that is correct.

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

Please run through this info and let us know if you have questions and what you find with it and we can go from there.

Thanks

That is great info. This is either a PCM or a sensor that is feeding the PCM faulty info.

So this is called open and closed loop. Basically the engine starts in open loop and runs off a preprogramed set of parameters based on the temperature sensors.

Then the PCM monitors the engine coolant temp and as soon as it is up to operating temperature, it switching to closed loop and monitors the o2 sensor data as well as the other sensors to fine tune the air fuel mixture.

See below for more detail.

What I would do to confirm this is the issue is unplug the o2 sensors and see if this does not happen at all. This should keep the engine in open loop and that would prevent it from acting up.

Do you have a scan tool that we can monitor o2 sensor data? If the o2 sensors are telling the PCM that it is rich then the PCM should be adjusting but if it is not then the PCM could be the issue. However, the PCM may be trying to adjust this but if the injectors are leaking then that would cause this as well. The only thing that doesn't support this is that you would think a leaking injector would not stop just because an o2 sensor is unplugged.

This is why we need to confirm that when changing the state of open to closed loop and back that the issue starts and stops. If it does then the PCM is the issue since you already replaced the o2 sensor.

The only thing that gives me pause is the o2 sensor that you replaced is also faulty but that is unlikely but not impossible.

Let me know if you have questions on this.

Thanks

Take a look at the info attached below. I have not replaced this on this vehicle but the manual shows it just on the left side of the steering wheel.

If it were me, I would replace this with a rebuilt unit as they are normally sold with a 30 day warranty. So if they are faulty they will change it out. However if it only last a couple years then that is far cheaper then going with a new unit.

Please see the process below for that info.

Thanks

Sounds great. Thanks for using 2CarPros.

Clearly not necessary but to help spread the word about the site, if you leave a review on this link below, it will help get it out there.

https://www.sitejabber.com/reviews/2carpros.com

Thanks

Oh wow. I figured that would have been it. If that is the case then we do need to confirm a fuel pressure issue. That means we need to check what it is at the rail.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

I attached the process below for both the 8 and 16 valve engines depending on which you have.

This would most likely be a regulator issue if you are correct and the fuel pressure should reflect that. Basically if it is high and not limiting the pressure then when the injectors are opening they are spraying too much fuel due to the pressure being too high.

At this point we can't rule out the new injectors. So that means what I would do is install the old injectors back in the vehicle solely to confirm the new injectors were causing that issue. However, when putting them back in, swap that suspect injector with another cylinder to see if the issue of it not changing when spark was removed moves to that cylinder.

This is just another way to confirm the injector was the issue but you just purchased some faulty injectors. This way we can confirm two things at the same time. First, the injector was the issue on that cylinder and two that the replacement injectors were faulty.