Misfiring????? PLZ HELP

[decoder22]

hey whats up guys i got a 2003 mazdaspeed stock with just a mbc and exhaust the mbc holds at 8 psi and spikes to like 10-11 ran fine for a lil but then it started bogging and throwing a code keeps saying misfiring 3rd cylinder and sometimes o2 sensor so i changed the 02 sensor and changed wires and plugs sort of helped and i turned the boost down but now it seems like soon as i come out of vacum it bogs????? my vacum is around 20 is that good? also what is max psi on a stock mazda speed whats a safe zone to run and anything you guys can sugggest would be great maybe coils???? car only has 73,000 am i boosting to high? or could it be vacum leaks but 20 vac doesent seem like a vac leak i dunno im just very lost i mean is there a stock mbc in the car that has to be removed or sumtin i just tapped the mbc of the bov line to the wastegate i found the diagram on here plz help me thx

[210_ZOOM]

what other mods do you have. You might be better off w/ a unichip? NOt too safe just upping the boost. Good luck w/ this. Dont have any other words of guidance.

[FlyinMSP]

Vacuum should be more like 22-23, if you have the stock airbox. It could be vaccuum related. Verify also the MAF connection. Does it idle rough?

[MSpeed2397]

I had a cyl 3 misfire...and damn was I in trouble...my engne is being rebuilt now. Take out the 3 cyl spark plug and see if there is any oil settled on top of the piston. That's what happened with mine. There was actually a recall for the 03 protege on the intake mani that apparently caused this problem. My buddy with an 03 dx got his entire engine rebuilt because of it. Since we use the same intake mani, I assume this may be the problem with more than just the regular series proteges.

[Kansei]

You said you replaced the spark plugs.. you didn't get Bosche, did you? Bosche plugs don't get along well with our cars.

[decoder22]

no i only use NGK the car has a cold air intake maybe a small vacum leak im thinking also. havent boost leak tested it yet also whats stock boost for this car? also how did u get oil on the piston and what does it have to do with the mani? did they tell you what they found or causes on the reason you needed a rebuild like bad compression or leak down test just curious i hope thats not my problem tho

[Dugg E Fresh]

Stock boost is about 5.5-6 (in most). Mine used to spike to 6 or so and settle to 5.5. I did the spring mod and now it spikes to 10 and backs down to 8-8.5, dropping a lil @ redline.

Not much help on the other questions, but I would go through all your vaccum lines. If they haven't been replaced, you should do that, they get pretty brittle.

Compression check?