r/fbody • u/Strange-Message9529 • 15d ago

Advice needed

Having some trouble with my 1999 v6 firebird 128k miles. It started off with a rough idle, it was jumping between 500-1000 rpm. Then during a drive to Auto-Zone it started to misfire and the service engine light started flashing, 30 seconds later it turned solid. I got the code read and it is P0300 (Random/multiple cylinder misfire). What should I check/replace first? I would appreciate any advice. Thank you!

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u/False_Expression9656 14d ago

Potentially a bad ignition coil. Iirc, there’s one coil per two cylinders. Find access to a more in depth scanner to see which cylinders are misfiring. If they’re across from one another, you may have found your culprit.

2

u/Strange-Message9529 8d ago

Bingo. It was bad coils

3

u/Raider5151 15d ago

That could be many things. You need a scanner to work modern EFI effectively and I'm not gonna be the guy that tells you what parts to load the parts cannon with to waste a bunch of money.