terrible random missfire at start up

[mspeedprotege]

last winter the car did the same thing random missfire only usually not on start up just randomly driving it would happen, but go away quickly. this year its been doing it on and off but not tooo badly untill last week. its at the point now where it could take up to an hour and 50 start up tries to get it to fire right. started with the cheapest fix first even tho i didnt think it would take care of the problem... new plugs.. no change. so before i started just spending wasted money on random parts i thought about what would make the computer and timing do something like this? ive unplugged wiggled every damn wire and connector i could find thinking possibly theres a bad connection somewhere. no change... i was thinking possibly a sensor maybe mass af sensor but idk or a cam sensor or something that would have to do with timing and ignition. im just looking for any reason that it could be. has anyone had this problem on the msp or have any helpful ideas?

thanks
kenny

 

[silvermsp88]

check ur crankshaft position sensor and ur camshaft position sensor, ur pcm needs to know where ur crank is to fire right same with ur cams. if u got bad sensors ur pcm isnt going to know when to fire ur coils.

 

[mspeedprotege]

check ur crankshaft position sensor and ur camshaft position sensor, ur pcm needs to know where ur crank is to fire right same with ur cams. if u got bad sensors ur pcm isnt going to know when to fire ur


ya i was thinking that too . i got new coils and wires coming the car could use it anyways but ill have to check both sensors and connectors better and get prices

 

[mazdaspeedp]

i say its probabley just the coils have they ever been changed?

 

[mspeedprotege]

not since ive owned the car 30000 miles ago. there were no records of the last owners changin them so im guessing they didnt. but im really hoping thats the problem and its not some ranom thing that will take a long time and a lot of wasted money to figure it out coils should be here in a few days so we will see

 

[mspeedprotege]

good news changed the coils today and no more missfire the cars running great again so if your car starts randomly missfiring change your coils

 

[trevormarsh]

Hello I have a similar problem. Changed my coils and crank sensor but no change. Only misfires when cold. It is a random misfire. Maybe change the cam sensor next? Any way to test the cam sensor?