Hey guys! I have a 5.4L 3v and have been having some weird issues. I'm pretty sure it's cam phaser related, but it seems a bit different than everyone else's issue. The truck runs great most of the time, but sometimes when going back down to idle or starting it while it's warm, it will stall and be hard to start. The only way to start it is to put the gas to the floor (clear flood mode) and then it comes to life, but you have to keep the RPMs up for 15 secs. Then, it's back to normal.Occasionally, when it's hot, it will start up way quicker than usual, like one crank, almost like your pushing the gas pedal. There are no loud clanks in the engine or anything, just some light ticking that it's had since I got it with 18,000 miles in 2018. It also threw an oxygen sensor and an exhaust leak code, but they didn't come back after they were cleared. All of these issues started at the same time about a week and a half ago. Thanks!
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It may not be the problem, but you might pull the vacuum hose off the fuel pressure regulator and see if any fuel comes out. That is one way extra fuel could be getting into the engine.

 

Could it maybe be an O2 sensor? It threw that code again today and it's staying this time.

 

What is the code that keeps coming up?

We need to be careful when attempting to consider repairs just by codes.

We need to realize a good part of the time it may refer to a sensor, but it could, be the sensor , it could be what is receiving the sensor info, it could be poor connections allowing the incorrect info to get to a component that makes the decision for something to be controlled. They haven't invented the tool yet to tell exactly what is malfunctioning and why.. So , we should be careful trying to read into a code something that can cost $$ and grief. A reasonable understanding of how a system works will help make better decisions on replacing parts..
Folks that consider these options , DO, come here for help and many times we can offer assistance based on our experiences and knowledge.

 

A bad O2 sensor for a 12 year old truck is not at all unlikely.

 

Can't assume that. I have two 87"s with the original O2's. So many O2's get changed because they throw a code when in fact they are doing their job.

An O2's data is not even used during open loop operation. So if the engine is having issues during the first few minutes after a cold start, it's unlikely the sensor. A code scan is a good starting point just to see if the computer is having input data issues.