Car hesitates when cold - CEL p0301
 

I need your help troubleshooting this one. Over the last couple of months the car has been running rough when cold. Pulling away in first gear under partial throttle the car hesitates, bogs down until around 3-4K rpm. Same thing in 2nd until I get above 4K or so. I recently got a CEL P0301 - 1st Rotor Misfire detected.

I tried clearing the ECU, brake tap, reset battery, hold mileage button in, etc. It seemed to help a little but still runs rough in the lower RPM range until it warms up. I did some wide open throttle runs to clear things out. However next morning, same issue.

I have 22,000 miles, 2004 MT. The dealer replaced plugs a while back when they did the cat check, around 15,000 miles. The only thing that has changed in the last six months is that I now do short commutes (less than 5 miles) in the city. The temp gauge indicates that it is warm when I stop the car.

Appreciate your input.

If you have warrant left. take it is. It will probably be a coil, or a wire. Why would you need to troubleshoot something you dont have to?

I have modded the car and don't want to have to restore it back to stock unless I have too. As the dealer would probably attribute any mods to the problem.

The mods I have done todate include: Agency Pulley, High Flow CAT, Light Flywheel, and CZ.

those mods wopuld have nothing to do with the problem. Im not a mazda tech, BUt where i do work we wouldnt look at those for causing a problem with the ignition circuit. It is electrical, not really powertrain.

running rough when cold has nothing to do with the ignition circuit.


take out the cz pull the battery cable then drive it for awhile to see if the situation returns if the cel comes back take it in. you probably have dieing coil(s) due to the CZ use.

Thanks for the info - I will try pulling the CZ and see if it returns to normal. If not, to the dealer I will go.

Update: Looks like CZ is part of the problem.

I turned the CZ off and the lower RPM hesitation went away. In fact it feels like I have smoother acceleration accross the entire RPM band. Perhaps my coils are close to the edge and the CZ was putting them over the top. I have been running the CZ for approx 2+ years.

I will continue to do some additional testing to see if there are other contributing factors.

excuse my ignorance but what is "cz" I also have the exact same problem when cold!

CZ = Canzoomer.............it was an add on ECU management system for our cars.
If you don't know what it is, then you don't have one.
Your issue is most likely plugs, coils, and wires......in that order..or maybe all three!

it was just a Greddy eManage POC