2007 Mazda CX9 3.5 liter FWD Sport.

Car drives fine for about ten minutes from cold start. Once warmed up I put it in park then once put into drive starts misfiring violantly. Put back into park and still misfiring badly nearly stalling. Put in park and rev wide open throtle and will not get above 2500RPM. Mechanic says scanner showed it has misfires all over. He wants to change plugs and coil packs. I changed plugs less than 100,000kms ago. Coils are original. I read somewhere that this could also be a problem with the ECU (bad driver). Fuel tank was filled up yesterday.

Yesterday, my wife was merging into the highway and the same misfire happened in drive and cut power. She was able to get off at the next close exit. Went to a gas station out some fuel in and then it drive fine.

Anyone experienced this with any CX9 or any other Mazda before? Any input would be greatly appreciated.

Thank You

 

Go with the advice from your mechanic, sounds logical for these old vehicles.

 

So mechanic told me that the PCM / ECM unit is damaged and would need to be replaced but could not find a used replacement. I am sending the PCM out to have it hopefully repaired which will also avoid having it being re flashed by the dealer. At the same time I am having all six coil packs and plugs replaced. Mechanic also found a small oil leak due to the valve cover gasket starting to fail. That will also be repaired. Hopefully this fixes the issue. Will take some time for the PCM to get back to me once being sent out for repair.