Engine runs rough and tries to shut off?

CAYNORE94

MEMBER
2005 CADILLAC STS
4.6L
V8
2WD
AUTOMATIC
143,000 MILES

I just bought the car listed above with the V8 4.6L Engine (I think that's right?). Anyways, the vehicle sat for two years before I bought it, and I was told all that needed done was the new fuel filter to be put on and the transmission cooler lines to be put back on and the heat shield above the drive line needed to be put back in place as well. I did all of these and also put Octane Booster in the tank along with 6 more gallons of new premium gas. I went to start the car and at first it started but it was rough, it didn't want to stay running unless foot was pushing in the gas pedal slightly, I went and charged the battery over night as to have a fully charged battery to help situations too, the next day it was having issues starting there was crank but no turn over, then my guy friend gets in and starts it holding the gas pedal in and was able to rec engine up ect. But it's still not wanting to stay running if the pedal isn't being pushed in some. Here is a list of things that I've noticed all right now with the car.

1.) On the push button to start there is a red light illuminating on the button it's self
2.) Dash says to shift to park even though vehicle is in park
3.) The passanger side of the dual exhaust turns glowing red hot
4.)Check engine light is

I can't think of what else 88.

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,645 POSTS

Hi,

I believe the answer to the problem is in the list of issues you indicated. If the passenger side of the exhaust is glowing red hot, it sounds like the catalytic converter is plugged. The only way to confirm is to remove the converter to see if it will stay running at that point.

Next, you really need to get your hands on a scan tool and check what codes are stored.

Here is a link that explains how it is done:

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

If you don't have a scan too, oftentimes a parts store will lend one to you. This really needs to be checked.

Back to the exhaust, you could have an injector sticking open and flooding the cylinder. Raw fuel getting into the exhaust can also cause the glowing. You could check if an injector is stuck by testing the fuel pressure drop-off or removing the spark plugs on that side to see if any are wet.

Here is a link that explains how to test fuel pressure. In this case, turn the key to run (engine off) and allow pressure to build. Turn the key off and see if the pressure quickly drops off.

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

This is where I would start. Also, if the exhaust is getting that hot, I don't recommend running it until we determine the cause. There is a risk of fire at that point.

Let me know what you find or if you have questions.

Take care,

joe