Engine accelerates roughly after high RPM use. (1 Viewer)

[Wayne]

The engine starts great, idles great and generally runs smoothly, except following a period of high RPM use, e.g. coming out of passing gear or after exiting the interstate. It doesn't do it 100% of the time, but it's becoming more often. It feels and sounds like the engine is missing when attempting to accelerate, and smooths out with only light throttle pressure. The problem eventually goes away and everything operates normally. I recently (5,000 miles ago) changed all the ignition parts, cap, rotor, wires and plugs, so I don't think it's electrical (although it could be). The fuel system has never been messed with since I've owned the truck. I'm not sure how to troubleshoot the fuel system. I do have a new fuel filter I'm going to install, but the pump, regulator and injectors I'm unsure where to start. I do own the FSM. What do you guys think?

 

[elhombre]

In light of the fact that it is fine some times, and crappy others, I would check 2 things. Is your air intake tube good to go with no holes in it. Next, I would look at the fuel pump relay in the driver's fender area. Below the ABS system. If the relay is slowly burning up the contacts, it can cause the problem you described.

You didn't say anything about any codes. The air tube will eventually throw a code (lean condition) , but the fuel system does not have a code for when the fuel relay is acting up.

Make it 3 things to check. How is the wire harness at the EGR pipe? With the engine torquing to one side under heavy load, some wires inside the bundle may have melted insulation and are shorting out intermittently.

 

[Chester]

Fuel filter would present these same symptoms.

 

[Wayne]

The engine air intake tube was replaced about 5 years ago and is in good shape. I'll replace the fuel filter and inspect the fuel pump relay. Thanks for your replies.

 

[baldilocks]

Sounds like it's possible that yiur egr valve is sticky and not closing quickly enough therefore allowing exhaust gases into the intake manifold at low RPM.

 

[NOAH8MUD]

Just wondering if you found the issue. I'm having the same exact thing happen to me.

Thank you

 

[Tools R Us]

Just wondering if you found the issue. I'm having the same exact thing happen to me.

Thank you

Have you checked the wire harness where it passes the EGR pipe. Should be tied to the support peg/bracket, so it can't contact the hot pipe.

 

[NOAH8MUD]

I have not, it just started this weekend, and it's getting worse but I have no dtc codes and it feels like a misfire. I'll take a look.

Thank you

 

[Wayne]

Well, I've taken procrastination to a new level, and I'm embarrassed to say I haven't replaced the fuel filter yet. I haven't experienced this issue in a while, so I've used that as an excuse to not change the filter. When the weather cools down some I'll "getter done."

 

[NOAH8MUD]

Ok, so dtc P0116 came on and I replaced the coolant temp sensor and it fixed the engine stumbling issue. Not sure how it's related but it's fixed.