Hey all, my Mazda B4000 has been running rough. Feels like i have a miss firing cylinder. I replaced the spark plugs and it worked great for the rest of that day. The next day I started it up and it was back to its old way. The wires look good so I dont want to spend to replace those unless there are people saying that I should, so other than that what should my next action be? I just had the cam shaft positioning sensor and the syncro unit replaced, not sure if that might have something to do with it.

 

take the negative battery cable off for a night, plug it in next morning and allow the truck to idle for 6-7 minutes, then report back.

could definitely be other issues but free fixes like resetting the computer are best right?

 

ok thank you i will post tomorrow how that turned out

 

Vacuum leak

Intake gaskets are known to leak and the upper to come loose.

 

Well reseting the computer seemed to work just fine, and now that you mention the vacuum leak. I get this low pitch hum while driving some times and turning on the air seems to get rid of it, and my A/C wont work. I never use my A/C so I have not tried recharging the unit. I have a friend that told me it was a vacuum leak. Any second thoughts?

 

The ac system is pressurized, if it gets leak it will just be normal air in the system and not work.

The HVAC door are operated by vacuum so if the air is going to the wrong place then there is a leak in that system.

The hum maybe a bad clutch on the AC compressor but its hard to say without hearing it.

 

hum could also be your airbox, mine does it on a select few random days when its warm. itll hum a perfect note till i feed it a good about of fuel. never solved why, but its so rare it doesnt bother me

 

That sounds like a bad or dirty IAC.