Hey guys i finished swaping out my engine in a 2005 4port with a factory rebuild motor that i bought from mazda dealer and its misfiring. I have a regular OBDII scanner so when i started it said cylinder 1 misfire and then it went to cylinder 2 misfire and it stays on like that even if i clear the codes. I put brand new spark plugs coils and wires so that shouldnt be a problem and the fuel is good too. Its a brand new motor and its mifiring already, i called the dealer and asked them if theres like a break in period and he said it should start right up with out breaking it in.

 

There are many many many reasons that a misfire can be occuring.

Removing the points that you already addressed, the short list is still:
- Grounding problem
- Plug wires on incorrectly
- vacuum leak
- ESS fouled
- Intake screens not in place
- MAF sensor fouled
- cat failure
- intake manifold valving not working correctly




I cringe at the fact that you bought a reman from a dealer... the reman quality is suspect and the profit margin is significant.

Mazmart could have sold you a better quality engine for cheaper.

 

this is how it runs cold, the rpms are jumping by it self and when i reved it, the 8 died on me and in the begining the car runs good but after 30seconds it starts shaking and rpms keep jumping

this is when the engine is hot, it runs good for 25seconds and then the rpms start jumping and the whole car is shaking

i got a really good deal for this is engine so it was hard to resist