Random Misfire

[Talon64]

Ok first thing is first. This started happening when I put a 7 bolt bottem end and a rebuilt head. At idle is lopes all over the place from 700 - 1400 rpm. Wide band goes from 14.7 to the farthest lean can go (---). I do have BC 272s. I know it would lope a little. I drove it for the first time and got a cyl 3 misfire so I cleared it and drop about 20 miles then cyl 4 cel came on. That night I changed the transistor, coil pack (came out of a running car) and put a new maf in (maf was bad). The cyl 3 and 4 cel havent come on yet but code P0300 comes on. I looked it up and its random misfire. I have new plugs and wires. Cam angle sensor was replaced about 15k ago. Im going to get timing checked tomorrow and see if its off. I dont think it is. Any idea what could be causing this? Thanks a lot

 

[TALONTRAX]

Are you running the original 7 bolt 2G style crank sensor . . . or is the car converted to the 1G cas to provide both signals like on a 6 bolt swap? If so, that`s your problem. If not, are you running a lightened flywheel(sorry,didn`t see your profile) I`ve seen it where lightened flywheels cause misfire codes due to decreased crankshaft harmonics, causing the ecu to sense the variation in pulses . . .

 

[Talon64]

Well the motor came from japan supposely came off a galant vr4. I used the bottem end and I used my old head but refreshed it up. Yeah I do have a lightened flywheel. Never happened before till I did the swap and the new cams I put it. Was wondering if the cams have anything to do with it? Maybe the cams and the lightened flywheel is making the code go off. Anyway to fix this? I can hear it misfire but the cel doesnt always come on. It sounds really bad.

 

[assault187]

Check the crank sensor, and the cam sensor behind the cam gear plate. You stated that you swapped out the coil pack and transistor, Just for good measure swap the plugs, check impedence on the plug wires and do a boost leak test to check for any leaks (considering you idle hops around and the AFR leans out)

see what you can come up with by dong this.


To get rid of the "random Misfire" code all togather, Send the ecu out and get DSMLink but its better to check and make sure its not an actuall problem 1st.