01 5.3L Sluggish at W.O.T.

SendyRado · April 18, 2018

01 5.3L sluggish at wide open throttle. Lift throttle maybe half inch or so and picks up a bit. If I slowly lift to the point in around inch or so from floor from when it starts to drag, it's fine. Starts really dragging at/past 4k RPM. Codes thrown: Mass Air, knock sensor #1 rear (i think), 02 sensor. Exhaust isn't restricted and converters not clogged or restricted. Cleared CEL and hasn't came back on but problem still occurs.

SendyRado · April 19, 2018

UPDATE: this evening the issue cleared up and went away, but there is also cooler air in the night (which would ?maybe? show the mass air being the problem). Will try to find symptoms again tomorrow when it warms up again. I am suspecting either fuel filter or mass air. Had similar issue on another truck and was fuel filter.

Big Whiskey · April 19, 2018

I had a similar issue on my 2000. It would hesitate at higher RPM's. Determined it was a clogged/bad fuel injector.

SendyRado · April 19, 2018

Pull each injector one by one and inspect while truck is running?

Edited April 19, 2018 by SendyRado

SendyRado · April 19, 2018

UPDATE: issue has not came back, it's inconsistency and symptoms, I assume to be fuel related and a filter/psi issue. Anyone's thoughts? Do appreciate Big Whiskey's input ?

txab · April 19, 2018

Have you bothered to check fuel pressure regulator? How about fuel pressure reading

SendyRado · April 19, 2018

Where would I find my regulator and where would I connect a fuel pressure guage to?

Mike GMC · April 20, 2018

Pressure regulator is on the driver's side on the fuel rail. It has a vacuum line to it. Pressure test port in on the rail on the passenger side. Should have a cap on it. Inside it looks like a big tire valve stem. It's called a shrader valve. You'll need a high pressure gauge to read it.