Car surges when driving

Tiny
LYNCHN202
  • MEMBER
  • 2001 CHEVROLET MALIBU
  • V6
  • 2WD
  • AUTOMATIC
  • 187,000 MILES
So I got this car from my brother. If I let of the gas and accelerate again it surges and feels like I'm rocking back and forth slightly. The rpm's also go up and down slightly. It does it between 45 and 60 mph every time I drive it. I have replaced the camshaft sensor. Spark plugs. Wires and coils packs since they were throwing codes. I've put fuel injector cleaning in the tank. My brother had replaced the fuel pump and filter a few months before I got it. I'm stuck on what to do!
Monday, December 2nd, 2019 AT 4:28 PM

5 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

Have you deleted the original codes that were present? Also, have any new codes come about? Have you checked for engine vacuum leaks?

Do me a favor. If you have a live data scanner, tell me what the short term fuel trims are. That could be very helpful to me.

Also, here is a link that covers the most common causes for a surge. Take a look through it. Many of the things you have already done, but something there may help.

https://www.2carpros.com/articles/engine-surges

Let me know.
Joe
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Monday, December 2nd, 2019 AT 8:34 PM
Tiny
LYNCHN202
  • MEMBER
  • 3 POSTS
Yes I have cleared the codes. No new codes have shown since clearing them. I fixed a minor vacuum leak and can't find any others. And I do not have a live data scanner.
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Tuesday, December 3rd, 2019 AT 6:44 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
If there are no codes, I suspect there are still other vacuum related issues. Electronics would have set a code again. If I knew the fuel trims, I could tell if there were additional leaks and identify how the computer is operating fuel ratios.

I'm not sure how you checked for vacuum leaks. If it was only a visual inspection, take a look through the following link and try what it recommends to find leaks. You could have a leak at the intake and not see it.

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

Let me know.
Joe
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Tuesday, December 3rd, 2019 AT 6:36 PM
Tiny
LYNCHN202
  • MEMBER
  • 3 POSTS
We checked for vacuum leaks using the carburetor cleaner method. Also replaced fuel filter to make sure it wasn't that and actually made the surging worse.
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Saturday, December 7th, 2019 AT 10:34 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

Is there any way you could get your hands on a live data scanner so I could know the short term fuel trims?
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Saturday, December 7th, 2019 AT 8:26 PM

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