Tachometer revs up and down, but when the lights are on works okay

1994 OPEL VECTRA
300,000 MILES
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BOBIBOEV
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  • 1 POST
If I do not repair it could there be a problem with the car's computer? The car is too old, and I will scrap it after 1 year maybe. It's a 1.7td Isuzu engine.
Jan 3, 2012 at 10:57 PM
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SQM
  • ✓ASE Certified Mechanic
  • 6,383 POSTS
  • ASE Certified Mechanic
Hello,

Is your check engine light illuminated? If the issue is with the computer, then it will trigger the check engine light. If so, you will need to scan and retrieve the code(s).

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

There could be a number of reasons why the idle is rough.

It could be due to a vacuum leak, worn spark plugs, dirty mass air flow sensor, dirty fuel filter. It can also happen due to a cracked intake boot.

Take a look at this article, it covers the typical issues:

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

Got through this guide and let me know what you find or if you have any questions.
Thank you.
Jan 31, 2022 at 3:12 PM
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