01 5.3L Sluggish at W.O.T.

[SendyRado]

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]

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]

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

[SendyRado]

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

[SendyRado]

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]

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

[SendyRado]

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

[Mike GMC]

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.

[sefiroxx]

You can rent a pressure test guage from one of auto parts chains

[Big Whiskey]

On 4/18/2018 at 10:23 PM, SendyRado said:

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

On mine....it eventually threw a code....and my buddy's tech 2 scanner showed an injector problem on one of the cylinders.