Engine runs rough at idle?

Tiny
BIGCHEVY404
  • MEMBER
  • 2003 GMC YUKON
  • V8
  • 4WD
  • AUTOMATIC
  • 73,000 MILES
My GMC yukon runs rough at low RPM such as when I come to a stop. Engine RPM drops to around 400-500. Engine shakes as if miss firing or about to die. No check engine light appearing.I had check engine light in past. Cant remember codes but they said (engine lean Bank 1& 2). I changed mass air sensor and put engine treatment in fuel tank a couple of months ago. No problems until yesterday. I was told in past it could be a bad intake gasket also. I have appointment at dealer Monday. Do you have any suggestions? Please HELP.
Saturday, January 31st, 2009 AT 6:26 PM

3 Replies

Tiny
JNOVACK
  • MECHANIC
  • 723 POSTS
I would check the Throttle Position Sensor, crankshaft position sensor, camshaft position sensor and fuel filter as for the engine lean bank 1&2 that would be the 02 sensors
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Saturday, January 31st, 2009 AT 6:55 PM
Tiny
JASON JOHNSON
  • MEMBER
  • 5 POSTS
Oh and o2 sensors are new but I didn't replace the harnesses and cats are not plugged.
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Monday, November 21st, 2022 AT 12:52 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
This is common when the fuel pump goes out be to be sure let's do a fuel pressure test by following this guide:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Fuel pressure .................... 385-425 kPa (55-62 psi)

Here is how to change the pump out in case you need it. Check out the images (below). Please let us know what happens.

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Monday, November 21st, 2022 AT 3:58 PM

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