Misfiring and cannot reach high RPM's past 3,000

1988 MITSUBISHI MIGHTY MAX
199,206 MILES • 2.6L • 4 CYL • 4WD • MANUAL
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CHUBBY CHIEF
  • MEMBER
  • 1 POST
Balls out once Istar hidden at 3000 rpm can't go past that without having troubles of hiccup or loses power going up hill. Horribly backfires like crazy and stalls out lagging with a start up when I turn the key off. Replace my spark plugs but is still acting like it's misfiring.
Aug 8, 2019 at 8:36 PM
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JACOBANDNICKOLAS
  • ✓Experienced Mechanic
  • 110,248 POSTS
Welcome to 2CarPros.

This could be a few things. Anytime I hear of a major power loss, I always suspect a plugged catalytic converter. However, other things can cause it. A large engine vacuum leak, fuel pressure, and so on can do it.

Take a look through these links and let me know if they help.

https://www.2carpros.com/articles/engine-backfires-while-running

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

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

Also, the vehicle should have an OBD1 system. Here is a link that explains how to retrieve diagnostic trouble codes from the vehicle's computer. See if you are able to get any.

https://www.2carpros.com/articles/mitsubishi-trouble-code-definitions-and-retrieval-procedure-for-odb1-system

Let me know if any of this helps or if you have other questions.

Take care,

Joe
Aug 9, 2019 at 1:39 AM
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