I'm here because my usual forum lacks greatly in technical knowledge of members, so I turn to the Honda community for their expertise. That forum is a Mazda forum. My car is a Protege5 and i'm having a misfire issue. It's a built 2.0L N.A. FSDE motor with standalone management. Anyways I pulled the plugs after running the motor for one of the first times since the build was finished and found Cyl's 1,2 plugs were sooty orangish brown all over and 3,4 were lightly carboned with some raw fuel on them. There's octane booster in the fuel. What would cause 2 of the cyls to be so much different than the other two, it runs rough obviously.The firing order is 1342. Please help Thanks.

 

Buy a Honda it'll fix all your problems

 

Check your distributor cap and rotor first to see if they're corroded. If they're ok, I know some of the older Mazda distributors use to go bad and misfire, so it could be a part on it's way out. Essentialy you have to start from the spark plugs and work your way back through the system to start ruling things out. If your management syestem is faulty, see if it works on another car, or swap in a stock ecu temporarily to see if it clears the misfire up. It's a troubleshooting thing....

 

It has 2 coil packs,cam and crank sensor no distributor. 2002 Protege 5 motor

 

Does cylinder 1 and 2 share the same coil?
Mileage on engine?

 

1,4 are on a coil and 3,2 are on the other.80,000 miles on the car,motor is a fresh rebuild. I'm thinking valve timing and or spark timing, but i'm not sure.

 

Being you have a standalone ecu, maybe swapping in a stock ecu would eliminate anything ecu/tune related? I assume youve already checked the basics. Compression, spark, cam timing?
Ive seen a couple dif fuel additives leave a rusty brown residue.
How old is the fuel? What kinds EMS?

 

Checked all listed except degreeing the cams. Old fuel, yes.will put fresh fuel in today. It's a Microtech LT10s.

 

Let us know how she runs with some fresh fuel.