Chevrolet malibu 2015 issues

Maintenance/Repairs
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1

Hi,
my car, a chevy Malibu 2015 LS 2.5L has been having some issues for a few weeks. Here is the full story:

  • Rpm are very low at idle (when in drive, higher when in park) and more importantly, it is not constant, stable over time, it goes up and down and sometimes it causes the car to stall. Stalls happened no matter if the car was in drive or in park.
  • When driving, the car loses power at some point, as if the engine was choking. Sometimes when going downhill and not pressing the accelerator, the car accelerates a little bit by its own during a small second as if more gas or air was suddenly coming up to the engine…
  • It is often hard to start the car, it cranks but starts only after a few seconds.
  • 2 months ago, the rpm went suddenly off after a pretty brutal jerking on the interstate (as if it has changed down a gear and changed it back suddenly or if the motor turned off). After that the rpm stayed on off and the check engine light went on.
  • Unplugging the battery and to plug it back seemed to temporarily solve the problems. It works during two/three days and I start having the same issues again.
  • I brought the car to Chevrolet and apparently the check engine light returned a message saying that the crank sensor was defective. They replaced the crank sensor twice, and they also fixed a vacuum leak in the engine.
    Even after that the car still has the same issues.
  • I don’t know if it’s linked, but check engine light went on about 6 months ago, this time for the oxygen probe. The mechanic told me that the probe was dirty, so he cleaned it and the light turned off.

Any idea of what could be the issue, and where to bring the car to be fixed?

Thank you

2

Has anyone tried cleaning the electronic throttle body?

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Tester

3

Not to my knowledge… So you think it is more an electronic issue than a mechanical issue?

4

The mechanic thinks it is the main wiring harness. He asks 1600$ for it. Do you think it could be the cause of all the problems?

5

Blaming the “computer” or the “main wiring harness” is really code for “we don’t know what your problem is, and hope you will go away.”

Find another mechanic.

3 Likes
6

How many miles?

7

You need to find a better shop and/or mechanic to figure this one out

When a guy wants to replace the main wiring harness, it’s a guess . . . and an expensive guess at that . . . because his diagnostic skills are weak and/or he’s not very systematic in his diagnosis

You don’t clean oxygen sensors

you replace them

and you figure out what caused the fault code(s) in the first place

Has anybody looked at fuel trim data?

Has anybody hooked up a fuel pressure gauge?

None of those would take very long at all . . .

8

Yes, that’s what I’m afraid about. And $1600 is a looot of money… So I won’t accept the job and either try to sell the car to someone who want to take care of the problem or a dealer or bring it to a junkyard…

9

it has about 120k miles and has a rebuilt title due to a wreck by previous owner.