Help!! Check Engine Light On!! Cylinder 4 Misfire

[VividMP5]

Hey guys,

I've got a problem with the MP5, any help would be appreciated!! Today while driving, I came to a stop light and the car decided to start stutter after applying the accelerator, and shorty after, the check engine light came on. I drove the car slowly to Autozone (which was down the street), and borrowed their computer tester and found out that cylinder 4's misfiring which read code (P0304). I went on to check the basic stuff like spark plugs and the wires and they're fine. And also I made sure that there's no loose connections, but still, the car is running on three cylinders, like s***! So now, I don't know what could be wrong! Any ideas? Thanks again in advance.

 

[azeli73]

From what I understand P0304 is almost always caused by accelerating a bit too hard while the engine is still cold. Did you have them clear the code at autozone?

 

[Action Jackson]

EGR Valve?

Intake manifold gasket?

Bad coil pack?

 

[jurgs01]

My first thought would be to take it to the dealer. If you want to do it yourself here is the procedure:


Good luck and I hope it is something simple.

 

[mastertech]

Hey guys,

I've got a problem with the MP5, any help would be appreciated!! Today while driving, I came to a stop light and the car decided to start stutter after applying the accelerator, and shorty after, the check engine light came on. I drove the car slowly to Autozone (which was down the street), and borrowed their computer tester and found out that cylinder 4's misfiring which read code (P0304). I went on to check the basic stuff like spark plugs and the wires and they're fine. And also I made sure that there's no loose connections, but still, the car is running on three cylinders, like s***! So now, I don't know what could be wrong! Any ideas? Thanks again in advance.

most likely the coil ...............we have done lots of these on p5's ,never rule out the plug or the high tension lead though...................are you under warranty? if it is still acting up then swap the coils...............if the miss-fire changes to the cylinder that you moved it to , then you know it is the coil, make sure to leave the plugs and wires in the same spot and just swap the coils. No what I mean .............hope this helps.

 

[Blue_Bullett]

most likely the coil ...............we have done lots of these on p5's ,never rule out the plug or the high tension lead though...................are you under warranty? if it is still acting up then swap the coils...............if the miss-fire changes to the cylinder that you moved it to , then you know it is the coil, make sure to leave the plugs and wires in the same spot and just swap the coils. No what I mean .............hope this helps.

The thing that I would start off with is small. Just replace all four spark plugs. It can't hurt. If that dosen't work then work your way up to the ignition wires. If you post pics of the condition of the plugs and such then maybe we can help.
It not much, but it's a start.

 

[VividMP5]

All fixed!!

Thanks for the replys, I found out it was the coil. It's weird, I thought if the coil is bad, then I would get mutiple misfires. Anyways, I swap the coils and rechecked it with the code reader, and it read P0302, so it's the coil. Thank god that's the only problem.(bowdown)

 

[mastertech]

The thing that I would start off with is small. Just replace all four spark plugs. It can't hurt. If that dosen't work then work your way up to the ignition wires. If you post pics of the condition of the plugs and such then maybe we can help.
It not much, but it's a start.

THAT'S WHY THEY CALL ME " MASTERTECH" APPRENTICE TECH, NEVER DIAGNOSE BY REPLACING PARTS, IF YOU HAVE TWO IDENTICAL PARTS AND YOU SUSPECT ONE IS FAULTY THEN SWAP THEM OUT AND RE- CHECK. WHY REPLACE PLUGS IF THEY ARE NOT REQUIRED...........HE COULD HAVE SWAPPED PLUGS THEN WIRES ETC UNTIL HE FOUND THE PROBLEM......................ANYHOW I KNEW IT WAS THE COIL ALL ALONG.

 

[jurgs01]

Or it could be a shorted wire that fries your other coil, and you are none the wiser(spin)

 

[mastertech]

Or it could be a shorted wire that fries your other coil, and you are none the wiser(spin)

IF THE WIRING WAS SHORTED THEN THE COIL WOULD BE DEAD , FRIED , ETC, ETC..................GIVING HIM TWO [2] MISSFIRE CODES COMMON TO THAT COIL..................HE HAD ONLY ONE............SO YOU KNOW THAT THE WIRING IS OK BECAUSE THE PROBLEM IS ONLY COMMON TO 1 CYL. NOT BOTH .THE COIL IS FIRING AND WHEN IT FIRES BOTH SECONDARY TOWERS ON THAT COIL RECEIVE A DISCHARGE TO THE HIGH TENSION LEADS , ONE OBVIOUSLY IS A WASTED SPARK SO THE PRIMARY IGNITION FOR THAT COIL IS INTACT[ DRIVER IN THE PCM] , THE PROBLEM IS IN THE SECONDARY DELIVERY TO THE SPECIFIC CYLINDER. IF YOU HAD TWO MIS-FIRE CODES SPECIFIC TO THE SAME COIL THEN I WOULD QUICKLY CHECK OVER VEHICLE FIRST.......................MAZDA RARELY EVER HAS WIRING ISSUES UNLESS RELATED TO ACCIDENT DAMAGE OR TIME ....20 YEAR OLD CAR ETC ETC.

 

[jurgs01]

Wiring problems are common on a site where a bunch of people mod their cars. Turn your caps lock off.

 

[mastertech]

Wiring problems are common on a site where a bunch of people mod their cars. Turn your caps lock off.

WHO MODS THE WIRING TO THE COILS ?????? TWO WIRES PER COIL......................NOT MUCH YOU CAN DO WITH THAT.BESIDES HIS SYPTOMS DID NOT MATCH TO A WIRING ISSUE. LIKE I SAID 2 DEAD HOLES ...........MAYBE..............1, NOT THE WIRING.

 

[jurgs01]

I am not saying you are wrong, just playing the devil's advocate. I would have swapped the coils too...matter of fact that's what I did when troubleshooting a similar problem. You should always check the wires before doing that for shorts or grounds. ALWAYS. I don't care if symptoms suggest that it's not a wiring problem. That's standard procedure and it takes like a second. It just so happens that one of the three wires going to the coil pack is connect to chassis ground, and one should be open to ground, and the last should have a resistance equal to the coil. I don't feel like arguing with you anymore because you insist on typing in all caps which is extremely annoying.

 

[Bijou-MP5]

wtf? turn off the damn CAP!
anyway, it's either wires or plugs problem.
did you wash your engine bay or something?
I did that once and water got in to the holes and had same problems but cleaned the holes and replaced the wires and it was good as new.