Check engine light on and white smoke from exhaust

Unfortunately, this points to a head gasket issue. So we need to rule that out before you move much further. Here is a guide on how to test this:

https://www.2carpros.com/articles/head-gasket-blown-test

You can also run a compression test but this is not as definitive as a chemical test on the cooling system but should be run as well.

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

Let us know if you have questions but let us know what this info is and we can go from there. Thanks

I used the blue devil product and followed the directions. Drive vehicle down the road about 1.5 miles. Vehicle still running rough and on way back vehicle started to overheat. It blew smoke out the exhaust at first but I didn't notice it on the way back just overheating.

So that is most likely misleadingly positive news. The fact that it is not smoking is good but now that it is overheating, I suspect you have a blockage in the cooling system causing minimal coolant to get to the possible issue in the head gasket which means it is not getting coolant to the place of the leak.

We need to use a laser temperature meter to find if there is a hot spot when this is overheating. If we can find a place that is hotter then an adjacent place that would be the blockage. Usually it is the radiator.

https://www.2carpros.com/articles/how-to-use-an-infrared-temperature-meter

Okay, I'll get laser temperature reader to use. Just curious though LLPif the vehicle didn't overheat at normal idle for 50 minutes per blue devil instructions. why would it on a test drive a few miles down the road?

Good question. It is most likely restricted and not fully blocked. So there is just enough coolant passing the restriction to keep the engine from overheating when it is just idling. Then when you add the load to it and increase the RPM there is more heat and it can't keep up so it overheats. This actually supports the idea of a restriction so I bet you will find it. I think it will be the radiator but it could be something else.

Oh okay. Sounds reasonable. I'll let ya know what I find out with. Thank you!

Sounds great. We will wait to hear some good news. Thanks for the update.