My 2001 4.8L 4X4 with 214K had a weird issue today: went to pass a landscape truck with half+ throttle (usually wants to break traction in the rear with more) and she was sluggish and didn’t respond well, did get the pass. While this was happening, my “check engine soon” light flashed, but when I resumed normal speed it went away. No check engine light. My foxwelltech found nothing.

…any ideas???

Thanks in advance!!

 

I'm starting with a fuel filter. Then maybe check the spark plugs though they are within millage. Then run a few cans of seafoam into the break booster vacuum hose. Then.......???

 

It seems I have a cylinder 3 issue (computer hooked up under engine running/loading) when the truck is under acceleration, ie. the engine is over 3500 rpms. To ensure it wasn't a coil pack, they were swapped and no change.
I am understanding that these engines have a oil pressure initiated lifter change when the truck is under acceleration.
Anyone know about this?
Is there an issue maybe with just a valve spring? Or a lifter? What's the fix? Engine head rebuild?

 

Since I have a 4.8L as well, watching this thread, but have no idea what to tell you. Personally I don't think there is a pressure initiated lifter change in these year model trucks, but I could be wrong. Looking through photos in my 1999-2006 Haynes repair manual, it sure appears to be a traditional pushrod that the camshaft pushes up against the rocker arms to open and close the valves, so it would only be impacted by engine RPM. The Haynes manual does give guidance on examining the rocker arm for wear. I would check the rocker arms and valves for cylinder 3 from the top side before I would go through digging deeper into the engine.

I read a lot of talk of "valve lifters" with the 2008 and later engines that have failures related to that due to adaptive fuel management (AFM), but that is not present on the 2001, or even my 2006 4.8L V8. It's just old school push rods and rocker arms, and the rocker arm compresses the valve stem to open the valve, against the pressure of the valve spring. Very much the same as the 1971 engine I rebuilt at age 16.

 

Thanks for your feedback. For information sake, my information on my second reply was from a "mechanic" who let me know why the issue comes up at or over 3500 rpms. But, as you said, it might be bunk as this engine should be like the ones you and I have messed with/rebuilt in the past. Your comments and my thoughts back on a V8 I had bend and rod and destroy a piston and put a hole in the block years ago (late 80's) makes me nervous as if a rod is worn and the lifter jambs/bends it can close and not let a valve open like it was in my case. I don't want the engine to be destroyed over a few bucks in parts. I'll look into locating a Haynes Manual.

Though the valve covers aren't weeping/leaking, pulling the one over #3 even if I simply install a new one is no big deal really, especially if I find a broken spring or a warn push rod.

Thanks so much for the info!

 

Did they swap plugs and wires with the coil?

 

I had a buddy assisting me and no, we simply swapped the coil. I'm thinking, and you assisted greatly, to swap the plug and wire. Great idea! (feeling silly that I didn't try that already)