2007 Mazdaspeed 3 Misfiring issues HELP

[Eustache]

I recently just had a 48k motor installed into my car because I blew my previous motor. The first day I got my car back, it was running faster then it has ever run before. Now, a few weeks later, I'm starting to have misfiring problems, ONLY when the car wants to go into boost. My mechanic told me it was a the Electronic Boost solenoid, so I bought a new one and had him put it in, but I'm still experiencing the same problem. He now recommends me to get new coil packs but before I start wasting my money id like to find out the problem from you guys. The car runs perfect and doesn't misfire when I drive it easy, but the moment I press down on the gas to activate my turbo it constantly misfires. The engine code is P0300 for random misfires and hopefully somebody can help me try to figure out my problem.

[gdawg25]

Check the plugs....and get a new mechanic.

[Eustache]

Well its a newly installed engine, with brand new spark plugs. I had him check the plugs already and they were fine

[robbspeed]

That mechanic sucks. Check the plugs anyway. Make sure they're gapped correctly. He probably gapped them to like .050.

Can you give us a log please also?

[broda]

The fact that he thought you were misfiring due to an EBCS should tell you to go to a different mechanic...

[dolbouck7]

did you find what the problem was?

Had similar issues that turned out to be the gap on brand new plugs that a local shop installed.

[bennyzoom]

Make sure you got the correct plugs, go to autozone or something and buy one of those spark plug gappers for a couple bucks. Take out the plugs and make sure they are gapped at around 0.028. Really simple, you can save yourself a trip to the mechanic and the money he would charge you.

[robbspeed]

Everyone should have a feeler gauge set. Those circular gapping tools suck and are inaccurate.

[tweed mike]

had a problem with my 07 ms3 falling on its face at about 4500 - 5000 rpm. pulled plugs and were gapped at .040 per box. set gap to .026 (which I found out thanks to you guys) and is running good. going to do a boost leak check next, just in case.

[Rcimp]

I recently read about someone else misfiring problem and he was getting P0300 and P0303 and it turned out to be a leaky #3 injector. He replaced that injector and the problem went away. I myself have the same problem. I am posing a new thread Dying Speed3.