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Misleading Misfire Codes?

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Old Sep 15, 2020 | 09:23 PM
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dakota_2_crossfire's Avatar
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Exclamation Misleading Misfire Codes?

Greeting everyone!

I was enjoying my Crossfire (2004 NA 6MT) today when I looked down to see a check engine light! I honestly don't know how long it was on for, as the cruise control lever perfectly covers that area of the gauge cluster!

Anyways, I drove the car to my local Oreily's and scanned the codes. They came back as follows:
P0304
P0306
P0301
P0300

I was really confused, as the car is driving completely fine, both before and after reading the codes. I would have never guessed it was a misfire issue.

I plan on cleaning all of the connection points for the engine wiring harness, but wanted some advice from the more knowledgeable here.

What should be my next course of action to fix my issue if cleaning off connections doesn't work? How can the codes pop up when the engine isn't bogging or running rough?

I noticed a somewhat foul smell coming from the car recently, but I'm pretty sure it's either my brakes or my clutch, since the car hasn't been driven for years before I got it.

Thank you everyone for your help! I look forward to hearing any suggestions that may solve my problem!
 
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Old Sep 15, 2020 | 09:40 PM
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pizzaguy's Avatar
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Default Re: Misleading Misfire Codes?

Not driven? Could be fuel or injectors.

But I will offer this: At around 95,000 miles, my Graphite generated misfire and O2 sensor codes but only when I "got on it". 12 plugs and 12 plug wires - and ALL of that stopped.
You can also measure the fuel pressure - if it is not 55PSI +/- 3 pounds, you have a problem.
 
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Old Sep 15, 2020 | 09:43 PM
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dakota_2_crossfire's Avatar
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Default Re: Misleading Misfire Codes?

The car is really low mileage. Only 53k. I have owned it for about 2 months and put on about 1k miles. Most of those miles were short trips, and I only drove it hard a little bit. The previous owner meticulously took it to the dealer if anything happened, but stopped around 2015. Either way, the car drives completely fine, so I'm not quite sure what to think at the moment. Thanks for the advice!
 
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Old Sep 15, 2020 | 10:14 PM
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pizzaguy's Avatar
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Default Re: Misleading Misfire Codes?

Originally Posted by dakota_2_crossfire
The previous owner meticulously took it to the dealer if anything happened,
I'd not have bought a car that was not properly maintained. I've heard of dealers who didn't even change the o-rings when changing oil/filter.
I'd be more impressed if you told me, "he did all the work himself..." (Did you miss my red, bold, italic sigline?????????????????)

Just remember; Misfires can be caused by:

Bad spark (common)
Bad fuel
Low fuel pressure
Fouled injectors
Major issues with the ECU (not at all common)
Filthy/impure electrical power to the ECU (Causes: Alternator with corrosion on the field rings, really bad battery, open or resistive battery cables/ground straps somewhere, etc.)

If the battery is more than four years old, or if the car really did sit for a LONG time - go get a new battery in the morning.
If you respond with "I had the battery tested", I will never respond to one of your posts again!
 
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Old Sep 16, 2020 | 12:20 AM
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ala_xfire's Avatar
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From: Lineville, AL
Default Re: Misleading Misfire Codes?

Bad spark (common)
Bad fuel
Low fuel pressure
Fouled injectors
Major issues with the ECU (not at all common)
Filthy/impure electrical power to the ECU (Causes: Alternator with corrosion on the field rings, really bad battery, open or resistive battery cables/ground straps somewhere, etc.)
Add bad coil pack(s) - right Crystal ???
 
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Old Sep 16, 2020 | 12:37 AM
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dakota_2_crossfire's Avatar
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From: California
Default Re: Misleading Misfire Codes?

Thank you everyone for your input. The battery is almost brand new, as the person I bought it from put a new one in just months before I bought the car. Since the car is acting fine other than having the Check Engine light on, should I try just clearing the codes to see what happens? I've had it before where they can go away for good. Just curious what everyone thinks. Thank you all for the help again.
 
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Old Sep 16, 2020 | 04:27 PM
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dakota_2_crossfire's Avatar
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From: California
Default Re: Misleading Misfire Codes?

Also this might be a stretch but I got gas right before the engine light came on. I got 91 from the gas station I always go to. Is there a remote possibility the gas I got could be bad?
 
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Old Sep 16, 2020 | 07:47 PM
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GraphiteGhost's Avatar
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From: Central South Carolina
Default Re: Misleading Misfire Codes?

Originally Posted by dakota_2_crossfire
Also this might be a stretch but I got gas right before the engine light came on. I got 91 from the gas station I always go to. Is there a remote possibility the gas I got could be bad?


Bad gas in California (with all those environmental regulations/laws)? Seriousely, if you think you got a bad tankful, change gas stations and fill it up with the highest octane available at the pump. Then get a can/bottle of octane boost and put it in that full fuel tank. After a 1/2 tank reset all the codes and recheck after filling up again with the highest octane at the pump. Come back after that and let us know if the codes returned, ok? Good luck!


.
 
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Old Sep 17, 2020 | 01:27 AM
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dakota_2_crossfire's Avatar
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Default Re: Misleading Misfire Codes?

I honestly think it might be. I drove the car again today and it is completely fine. The light is still on, but there is absolutely no issue idling or it bogging down/chugging. Still as strong as ever. I was just going to clear the code, but I will definitely try what you suggested. If that doesn't work, then I assume it must be a bad sensor somewhere. Thank you for the suggestion!
 
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Old Sep 17, 2020 | 02:55 PM
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dakota_2_crossfire's Avatar
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From: California
Default Re: Misleading Misfire Codes?

Well so far good news. After having a friend drive the car, he confirmed my suspicion that there was in fact no misfire. I got my code reader this morning and erased the codes and took the car for a test drive. So far, the CEL hasn't come back, and the car still feels completely fine. Right now I'm chocking it up to the car getting confused in one way or another. Hopefully this issue stays fixed! I already have plenty of other things that need to get fixed instead LOL. Thank you all for the help and support.
 
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