Rough running new engine
 

Howdy one and all

Here goes. I have a 2006 F150 5.4. Recently had an engine put in the truck at 143,000 miles. They replaced everything at the dealership. I got the truck back and it ran like crap. I understand there is a learning system to the engine and computer, but, no matter what this truck ran like crap. Took it back and the tech hooked up the computer to the truck and we found out there was an update to the truck system. we ran the update and took it for a ride. Everything checked out on the computer.

Here is the main issue I am having, and they can't seem to figure it out. When the truck first starts up in the morning or after sitting for an extended period of time, the truck pulsates. when it pulsates it goes from running perfectly smooth for about 10 seconds to a slightly rough idle for about 3-4 seconds. this repeats until the truck is driven and then it is hard to feel the roughness.

When you are at a standstill and slowly excellorate the truck has a vibration that feels like a rough idle and then slowly goes away before shifting gears. When the truck comes to a stop the RPMs drop slightly and there is a rough idle for a few seconds and then smooths out.

I'd be looking at 2 things. One would be fuel pressure. It may be that it's on the lower limit when it's running right but when the engine is cold, it falls below the threshold and the engine is basically running out of fuel but then it catches up and idles right until the pressure falls again. I'd be looking at injectors. Most apparently you one or more that are bleeding down when the engine sits for any length of time. Even new injectors are no guarantee that an injector is bad. My money would be on a bad injector(s). There is no "learning" to the ECM to make it run bad. It's already programmed in the ECM to make it run right from the first turn of the engine. Regardless, it should be coding up a miss in the engine. If not, the ECM may be bad or going bad.

I wouldn't be messing with any of it. I'd tell the shop that installed the engine to fix it.

This. Also was it a used engine, new engine, rebuilt engine or what? What all was replaced along with the engine? Particularly what parts of the fuel and emissions systems? Where the various engine sensors replaced with new ones, or from the original engine or did they came from the replacement engine?

It could literally be any number of causes. Sensors, coil (COPS), fuel-system, wiring harness, etc. If I paid a shop to drop in an engine, it better work like it's supposed to.

If it's a fuel pressure issue it could be the FPDM.

This is a reman engine from Ford. To the best of my knowledge, everything has been replaced. It was a job done under warranty. The only thing that they could find was there was a 1% compression loss at number 6 and they told me that could work itself out as the engine is run overtime. I buddy of mine told me it could be the torque converter might be going bad.

^^

Keep it there till it's fixed. It's not your problem.

As soon as you start disconnecting things, wrench turnin', etc, they can easily pull a fast one and say you did it.

Quit being antsy and playing mechanic, and just let them fix it. Especially since it's a Ford dealer.

a big X2. Make them give you a loaner until they fix it properly.