Runs rough and misfiring

Tiny
ANTHONY HILES
  • MEMBER
  • 2001 PONTIAC FIREBIRD
  • 3.8L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 171,000 MILES
When in park won't rev past 4,000 rpm's. When driving acts like it's misfiring. Replaced plugs, wires and coil packs. Also catalytic converter. What else could it be?
Do you
have the same problem?
Yes
No
Tuesday, April 14th, 2020 AT 6:05 PM

1 Reply

Tiny
KASEKENNY1
  • EXPERT
First the not revving past 4,000 RPM's sounds normal because these engines have a rev limiter on them so you don't hurt the engine.

When driving and it acts like it misfires, is there a check engine light? Let's pull codes if there is. Here is a guide on how to do that:

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

If there are no codes, it sounds like you ruled out the ignition system for now. Let's address the fuel issue next. Hopefully there is a code that can point us to a specific cylinder. Again, if not here is a guide that will help:

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

If we don't find anything here, we may not have a misfire but instead a vacuum leak that is causing the engine to run rough. Here is a guide that covers these items:

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

Let me know what you find with all this info and we can go from there. Thanks
Was this
answer
helpful?
Yes
No
Tuesday, April 14th, 2020 AT 6:24 PM

Please login or register to post a reply.

Sponsored links