2003 Eclipse GT Tachometer Gauge (Hunting Idle) P0300 Random Misfire

Trying to diagnose a P0300 code (Random Cylinder Misfire).

Replaced the: Plugs, Wires, Distributor Cap, Rotor Button, Air Filter.

Checked the: Compression, Fuel Injectors (Ohm Test Only), and Throttle Body (Sea Foam Clean).

I also looked for vacuum leaks with a can of carburetor cleaner, and went through the entire can without finding anything.

Vehicle Info: 2003 Mitsubishi Eclipse GT, 3.0 V6, 92k miles. P0300 issue since 70k miles, and is only apparent at idle and through code throwing. No drive ability or power issue whatsoever. Slightly less than average fuel economy. Misfire more apparent during winter. Any help would be appreciated.

Category:

Autos & Vehicles

Tags:

• p0300
• misfire
• eclipse
• gt

[EricTheCarGuy]

You might want to do a power balance test to see if you can verify that it actually is cylinder #3 that is the problem. If you find that it is you might check the fuel injector for that cylinder as it may be having issue, I say this because by your description you seem to have covered everything else. Keep me posted.

[aceofstyle]

@EricTheCarGuy Thanks for taking a look at my problem Eric. I can't verify which cylinder is misfiring (I thought P0300 was random), and I just tried cleaning the IAC, and did the power balance test you suggested. The power balance test showed to me that there was an equal amount of power loss with each cylinder coil unplugged, and not one weak cylinder.

I'll try and stay on top of this until I find out what's wrong.

[EricTheCarGuy]

@aceofstyle Just for the heck of it you might want to look into an injector cleaning, not the kind that you get in a can and dump into the tank but a professional job done with an injector cleaning kit. Also make sure you are using the recommended plugs for that engine, cheep spark plugs can cause all kinds of problems.

[aceofstyle]

@EricTheCarGuy I think I'm going to have to do that as my next step. Here's a video of the idle with the o2 sensor before the CAT unplugged. Just looking to see if my CAT is plugged up or not. I can't tell if it's fixed. I "think" it's idling better but I don't know if that's 100%. What do you think? (I'm not sure how to send it but it's titled "2003 Eclipse GT Tachometer Gauge (Hunting Idle) P0300 w/ CAT UNHOOKED") I appreciate it Eric!

-Mike