Help: Code P0300 H C

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Oct 22, 2005 | 12:56 PM

GS348

Thread Starter

Burning Brakes

Joined: Jul 2003

Posts: 811

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From: Nashville TN

Help: Code P0300 H C

I believe this code to be a misfire. I replaced the plugs and checked the wires befor I reinstalled them. The code remains and the car still runs rough...any ideas?

MJP

Oct 27, 2005 | 11:44 PM

JR_VET

Burning Brakes

Joined: Sep 2004

Posts: 1,056

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From: Havelock, NC ( NJ Resident )

be a misfire

Quote:

Originally Posted by GS348

I believe this code to be a misfire. I replaced the plugs and checked the wires befor I reinstalled them. The code remains and the car still runs rough...any ideas?

MJP

Question1. have you placed some long tube header on your car? If so you need to check the o2 sensors to ensure they on right, the back o2 sensors for the pass side plug in on the driver side and the other on the pass side. break out your books a make sure they properly installed and not close to the headers. clear code and try it again.

Oct 28, 2005 | 06:26 AM

Gatzer

Instructor

Joined: Apr 2005

Posts: 246

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From: Dayton, Ohio

Any new mods added to the vehicle?

A cam will also throw this code.

Oct 28, 2005 | 08:55 AM

ToplessTexan

Safety Car

Joined: Aug 2000

Posts: 4,154

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From: Murphy TX

Cruise-In II Veteran

When did it start? Any obvious fouling of plugs? Do you have access to a scanner? That would let you look at misfire counters which would point you to offending cylinder(s).

Oct 30, 2005 | 05:07 PM

leojnknsC5

Melting Slicks

Joined: Sep 2005

Posts: 3,082

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From: eagle mountain utah

Misfire codes

You can get a misfire code from either a spark plug that doesn't fire or an injector that isn't allowing enough fuel or allows too much fuel into the cylinder. If you get the misfire code without a "lean fire bank1/bank2" code or "rich fire bank1/bank2", it's probably not an injector.

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