Random Misfires

[whybee]

Hey guys, I recently purchased a 2013 mazdaspeed3. When I purchased the vehicle it had a bad homejob exhaust system with the downstream O2 sensor deleted and was running rich and throwing CEL. I replaced that with cobb 3 inch turbo back and installed a new O2 sensor. That got rid of my O2 sensor code but now I have P0300 that comes back no matter how many times I reset it. Changed all 4 spark plugs, cleaned intake valves, changed intake and tip, all 4 cylinders check around 150-160 compression, and I cannot see or hear any exhaust leaks just rechecked on lift yesterday. Here is a log of right when it started flashing on in the taco bell drive through.

[Vansquish]

When you changed your spark plugs, what was the gap in the plugs?

[whybee]

Gapped NGK 6510s to .026 per my tuner. The stock Mazda's were also around there when pulled out. I'm at 68k.

[Vansquish]

Originally Posted by whybee Gapped NGK 6510s to .026 per my tuner. The stock Mazda's were also around there when pulled out. I'm at 68k.

Have you tried moving around each of the coil packs? I know it is a p0300 code, and that indicates a random misfire. However, it may be possible that one or more of the coil packs is dead or dying. You may also want to consider finding somebody local to you and swapping coil packs with them just to test.

[whybee]

Originally Posted by Vansquish Have you tried moving around each of the coil packs? I know it is a p0300 code, and that indicates a random misfire. However, it may be possible that one or more of the coil packs is dead or dying. You may also want to consider finding somebody local to you and swapping coil packs with them just to test.

I might try and order a couple if they aren't too expensive, I haven't seen a single mazdaspeed in Tucson sadly. However, I just went on a nice drive trying to burn off this tank of fuel in case it's the issue and either I'm tripping or it seems to backfire whenever I see the EGR command come up. I'm mostly only seeing this at cold start and idle in general.

[Vansquish]

Originally Posted by whybee I might try and order a couple if they aren't too expensive, I haven't seen a single mazdaspeed in Tucson sadly. However, I just went on a nice drive trying to burn off this tank of fuel in case it's the issue and either I'm tripping or it seems to backfire whenever I see the EGR command come up. I'm mostly only seeing this at cold start and idle in general.

What exact tune are you running? Also please list all your mods in your signature. That may help us diagnose your issues in a more streamlined way.

[whybee]

Originally Posted by Vansquish What exact tune are you running? Also please list all your mods in your signature. That may help us diagnose your issues in a more streamlined way.

Sorry man, added a sig. still in the process of sending logs and having tune updated but had the code before on the Cobb safe mode flash as well.

[Vansquish]

What SRI/TIP are you using? Is it stock sized, or something else? It's important to know the diameter of the MAF housing in order to help diagnose problems with your car.

[whybee]

Originally Posted by Vansquish What SRI/TIP are you using? Is it stock sized, or something else? It's important to know the diameter of the MAF housing in order to help diagnose problems with your car.

Corksport, should be stock diameter.