Got a CEL today

[liquidflem]

So i was driving my car around, normal speed, normal driving; and my CEL came on.

I took the car to Autozone and they said it was a code P0300 or "random misfire"

I feel absolutely no difference in the way the car handles, feels, sounds, etc. Only mod is a Cobb SRI.

I'm taking it in tomorrow for another issue and will show them this. Just wnated to see if you guys had any insight.

Thanks!!
Noah

[slowtege5]

Could be the plugs, wires, vacuum leak. How many miles on the car? I would start with the ignition system since it isn't that costly, then go down the list

[MRT_MS3]

Im in the same boat as you with the same mod. Instead of the P0300, I got a P0303 which is cyl misfire #3. I will re-install the intake this coming weekend to make sure everything is tight. I read somewhere that the turbo inlet sometimes comes loose and needs to be tightened and this could cause this CEL.

I've reset the code and for the past few days, its been pretty good.

[MicaSp33d]

uh oh ... a "change engine light" ... j/p

had the same code when my engine decided to bend one of its rods (before it blew) ... hopefully it works out for u.

[funksilver07]

Technical Description

Random/Multiple Cylinder Misfire Detected
What does that mean?

Basically this means that the the car's computer has detected that not all of the engine's cylinders are firing properly.

A P0300 OBD DTC code indicates a random or multiple misfire. If the last digit is a number other than zero, it corresponds to the cylinder number that is misfiring. A P0302 code, for example, would tell you cylinder number two is misfiring. Unfortunately, a P0300 doesn't tell you specifically which cylinder(s) is/are mis-firing, nor why.
A code P0300 may mean that one or more of the following has happened:

* Faulty spark plugs or wires
* Faulty coil (pack)
* Faulty oxygen sensor(s)
* Faulty fuel injector(s)
* Burned exhaust valve
* Faulty catalytic converter(s)
* Stuck/blocked EGR valve / passages
* Faulty camshaft position sensor
* Defective computer

[matsuda]

A code P0300 may mean that one or more of the following has happened:

* Faulty spark plugs or wires
* Faulty coil (pack)
* Faulty oxygen sensor(s)
* Faulty fuel injector(s)
* Burned exhaust valve
* Faulty catalytic converter(s)
* Stuck/blocked EGR valve / passages
* Faulty camshaft position sensor
* Defective computer


All the OP has to do is replace all of the above parts and he'll be good to go. (rei)

[funksilver07]

There you go...haha.(spin)

[liquidflem]

It's happened twice over about 4 months. It goes away after about 2 starts, though. Car seems fine. Weird.

[_Toxic_]

It's happened twice over about 4 months. It goes away after about 2 starts, though. Car seems fine. Weird.

Have u taking it to a mazda dealer? Warranty?

[CWPspeed3]

Im in the same boat as you with the same mod. Instead of the P0300, I got a P0303 which is cyl misfire #3. I will re-install the intake this coming weekend to make sure everything is tight. I read somewhere that the turbo inlet sometimes comes loose and needs to be tightened and this could cause this CEL.

I've reset the code and for the past few days, its been pretty good.

I got that cyl 3 misfire when i first picked up my car before it left the garage with <10 miles on it. The tech went through an odd procedure of turning the car off then on and holding it at 4k rpm for 2min then the car shut off, turned back on and was fine. I havent had a problem in 1.5yr 16k miles. no explanation of what caused it but id take it to the dealer.

[ElGaspo]

with <10 miles on it. The tech went through an odd procedure of turning the car off then on and holding it at 4k rpm for 2min then the car shut off,


OT, but if that would have been done to my car, the sale would have been voided and i would have waited for a new car. color me paranoid, and i'm glad it fixed the cel, but no way on God's green earth would i subject a brand-new car to hold at 4k rpm for 2 full mins just sitting still....:'(

[MicaSp33d]

i believe he was cleaning the spark plugs. I think it says it somewhere in the service manual.

[_Toxic_]

i believe he was cleaning the spark plugs. I think it says it somewhere in the service manual.

True!

[Falango]

If he reset the battery first, that is usually one of the procedures to set the emissions monitors. I'm pretty sure the emissions monitors need to be set for the ECU to properly output engine codes.

[liquidflem]

Have u taking it to a mazda dealer? Warranty?

I did take it in once for this and they said it wasn't a misfire and said it was something else i could ignore. I think they were pulling my leg, though. I haven't had a single good experience at this dealership.

[_Toxic_]

I did take it in once for this and they said it wasn't a misfire and said it was something else i could ignore. I think they were pulling my leg, though. I haven't had a single good experience at this dealership.

I feel u on that! i too have had bad experince with my dealer...u try too be nice and explain your problem and what you self think it could be, and they just "yeah yeah.. dont think about it, it will go away...." ignorent assholes...(chair)

Iam going in now to mazda for the second time for my oil leak... guess tightened the bolts didnt help.. (1st, time) (unamused)

[08cosmic3]

Do not go to the dealer with the Cobb intake on. They can void your warranty.

[LittleRedWagon5]

Mine started doin the same thing. But after it warms up it runs fine. But before that around 3-5k rpm's it misses and bogges. I replaced the factory plugs with new factory plugs. I also got the random misfire code. Any ideas ?

[iredremix]

got this problem as well. my car's been fucked up for about 7 months now.. i need help on this one. i replaced my spark plugs with OEM's and replaced coil pack #3. everything seems fine, until i reverse. when i reverse, the misfiring starts.. after that, the car misfires in all gears.. i drove around ~100 miles without reversing and it never happened. any idea why reversing is triggering this?

[cudaman]

got this problem as well. my car's been fucked up for about 7 months now.. i need help on this one. i replaced my spark plugs with OEM's and replaced coil pack #3. everything seems fine, until i reverse. when i reverse, the misfiring starts.. after that, the car misfires in all gears.. i drove around ~100 miles without reversing and it never happened. any idea why reversing is triggering this?

If it's always CEL with cylinder 3 misfire, it could be the injector. Move the injector down one cylinder to see if the CEL follows #3 to cylinder 2, giving a random misfire in cylinder 2. If so, bad injector. Could also be wiring to injector from PCM if it stays at #3.

[iredremix]

If it's always CEL with cylinder 3 misfire, it could be the injector. Move the injector down one cylinder to see if the CEL follows #3 to cylinder 2, giving a random misfire in cylinder 2. If so, bad injector. Could also be wiring to injector from PCM if it stays at #3.

thanks man.. gonna give it a try somehow.. sucks that i don't know how to get to the injectors

[badgerspeed3]

Just got my first CEL yesterday leaving work yesterday. It popped on under normal acceleration leaving the first stop light, and I didn't notice anything strange. It was driving smooth so I kept driving home babying the hell out it. It only has 10,700 miles.

Dealer said it was a P0300. Ignition and fuel pressure were within spec, and it ended up being the crank sensor. They found a lost wave form from the sensor at rpm over 2500. The gap between the sensor and the target wheel was "out" (too big i'm assuming). They put the gap back in spec, and everything's fine.

It's still early since it just got fixed this morning, but hopefully that's all it was. Thought I'd throw that out there since I didn't see that anyone else getting P0300's had checked this. Good luck.