Engine hesitates when accelerating?

Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
I forgot to ask litre size of engine?
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Thursday, September 10th, 2020 AT 2:31 PM (Merged)
Tiny
CALEBA2012
  • MEMBER
  • 2 POSTS
It's a 5.3 v8, I took to autozone and they said it was the MAF, I changed it and it is still doing that. The check engine light flashes when I press on the gas.
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Thursday, September 10th, 2020 AT 2:31 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
What was the actual code number? The code doesn't tell you what to replace, just that the system thinks there is a problem on that circuit, somewhere.
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Thursday, September 10th, 2020 AT 2:31 PM (Merged)
Tiny
CRYPTOKING
  • MEMBER
  • 27 POSTS
  • 2003 CHEVROLET SILVERADO
  • 4.3L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 273,000 MILES
Recently replace lower and upper intake manifold gaskets. Replaced fuel injector spider, distributor, distributor cap and rotor, new spark plugs and wires, and crankshaft position sensor. Cleaned Throttle body. Fuel pressure is 65 PSI. New fuel filter. No codes being sent. Any ideas? It starts quickly and idles well but when trying to take off, it stumbles, hesitates and sometimes backfires. Checked timing and it's good.
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Monday, October 26th, 2020 AT 12:12 PM (Merged)
Tiny
DANNY L
  • MECHANIC
  • 5,648 POSTS
Hello, I'm Danny.

It sounds like you may possibly have plugged catalytic converter or converters. Most exhaust or muffler shops can check for you. Not having check engine light on or codes stored makes it hard to diagnose but with that high of a mileage that it what I think. Here are a few tutorials to view about Catalytic converters:

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

After having this performed keep us updated and we'll go from there. Hope this helps and thanks for using 2CarPros.
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Monday, October 26th, 2020 AT 12:12 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
Hi,

Prior to replacing the gaskets, did the vehicle act the same way? Also, you indicated fuel pressure at 65 psi. Is that with the engine off? I ask because max (according to the manual with engine off) is 62. (see pic 1)

Is there any black smoke from the exhaust? Have you checked for vacuum leaks?

If you haven't checked for vacuum leaks, start there. Make sure everything on the air intake tube is back together properly and tight. Also, it's easy to leave a vacuum hose off. Here is a link that explains how to check:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Let me know if his helps, what you find, or if you have other questions.

Joe

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Monday, October 26th, 2020 AT 12:12 PM (Merged)

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