Fuel injector

Just to be sure we are on the same page; the engine is now running but it runs rough, and you can smell gas in the exhaust?

If that is the case, then yes this could be fouled spark plugs.

Let's start with removing the plugs and see what they look like. Basically, we need to see if they appear to be fouled, which could be the cause of the current issues.

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

Basically, what happens is if the plugs get soaked with fuel, then they can get fouled and no longer operate properly.

So, if the plugs are fouled then we could have a plug issue. However, when you changed the plugs and coils, this is when you had a misfire? Or you replaced the plugs and coils to repair a misfire?

Let's start with this and go from there. Thanks

Sounds like you could have a leaking injector. Were all the plugs wet when you found it not starting the first time?

Try holding the accelerator to the floor and start it and see if it starts better. If it does then it is flooded.

However, before you do anything let's get a picture of the plugs so that we can see the electrodes and that will tell us if they are fouled.

Okay. If that is the case, then I would replace them and see what happens. Sounds like they are fouled and now you are experiencing the results of fouled plugs.

Depending on what happens, we need to go back to the beginning and act like none of this happened. We need to figure out what the vehicle is doing now which will point to why it is doing it. If we continue to try and figure out what happened rather than focusing on what is currently happening, then we will keep chasing it.

So basically, we need to use a scan tool and monitor the o2 sensor data and find out what it is telling us when it is running poorly.

Also, can you get a recording of what it is doing so that we can be sure we are on the same page. When you say it is starting rough and then running smoothly, how long before it smooths out? A video may be the best thing to do.

Okay. Just to be clear. You replaced the plugs, and it was fixed? Then a day or so later it started running rough again?

There are a couple things that come to mind. First is you have leaking injectors. I understand you replaced them, but I am thinking that it may be worthwhile to install the old ones one at a time and see when this stops.

What it sounds like is the engine has slightly too much fuel and once the engine starts, it runs poorly until it flushes that excess fuel out and then smooths out.

A way to check this is to put a fuel pressure gauge on the engine and then shut it off and what the pressure. It should hold steady for at least a few minutes then slowly drop over time. I suspect this will drop quicker than it should which would point to this.

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

I am curious what the o2 sensor info is when this is running rough because I suspect it is rich. However, I would start with this other stuff first.

I understand. However, if you are in the USA then if you have a parts store like AutoZone or one of the others, then most have tool rental programs that are free unless you don't return it.

However, if you replaced the plugs and didn't start the engine then it is more than likely these plugs are not wet. Then you drove it and let it sit, the injectors leaked soaking the plugs and when you restarted it, the issue returned.

Clearly this is just a theory but one that would need to be tested using the pressure tester so hopefully they have the free rental program.

I could be wrong, but I have rented tools from both of them, and I think that is just a deposit. In other words, when you return the tool, they give that back.

It is just a way to make sure you return the tools because you could buy most of these cheaper than that.

The only other way that I know to test this is to take the replacement injectors out and put the original ones back in because it doesn't sound like they were the cause of the original issue. So, if you put those back in and this rough starting issue stops then you know one or more of the replacement injectors were leaking.