Running rough

Tiny
CHEVY1234
  • MEMBER
  • 1997 CHEVROLET SILVERADO
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 160,000 MILES
So, the upper intake gasket along with two fuel injectors were replaced on my 5.7l vortec. I did not do the repairs so I can only go off of what the other person (my brother) says. I have no taillights which worked before, the truck will stay running sometimes but it's very rough. As far as the rough running. He said he thinks he sucked a paper towel into one of the intake ports, but he is not positive. Would that make it run rough? I have asked a few people and keep getting mixed answers. How would I even check that? The taillights I'm hoping it's just a fuse but I don't know if he fried something or what. I tried plugging the scanner in but all I'm getting is an O2 sensor code that's been there since I owned it. I just need to figure this out. Thank you.
Sunday, February 27th, 2022 AT 8:34 AM

5 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

Wow. If a paper towel was drawn into the intake, yes that will cause issues. If that is a possibility, you really should remove the throttle body and see if you can locate it.

If you look below, I provided the directions for the removal and installation of the throttle body. This is where I would start.

First, do this so we can confirm there is nothing blocking the intake.

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

Take care,

Joe

See pics below.
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Sunday, February 27th, 2022 AT 8:46 PM
Tiny
CHEVY1234
  • MEMBER
  • 4 POSTS
I took the upper plenum off and checked all 8 ports. He said he had one in each port, so nothing went in there. If he left one in, put everything back together, and started it. Wouldn’t it get sucked into the engine?
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Monday, February 28th, 2022 AT 3:57 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

It could have been drawn in by vacuum, but that would really depend on size. Plus, where would it have gone? I would like to think it got burned up, but it may have caused other issues.

Have you scanned it to see if there is a specific cylinder or cylinders causing the issue?

Let me know.

Joe
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Monday, February 28th, 2022 AT 2:40 PM
Tiny
CHEVY1234
  • MEMBER
  • 4 POSTS
I ran codes and there is only an O2 sensor that’s been there since I’ve had it. I also checked cylinder compression an all are between 120-140.
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Tuesday, March 1st, 2022 AT 4:47 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

If it is a rough idle, have you checked to see if there are any vacuum leaks, and have you checked fuel pressure? Also, let me know what the code is for the O2 sensor. It could be causing issues.

Here is a link that explains how to check for vacuum issues:

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

Let me know.

Joe
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Tuesday, March 1st, 2022 AT 7:34 PM

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