I have a mazda b2600i p/u, 33,000 mi. Ran great, then out of the blue started to run very rough, black smoke, etc. I have had the distrb cap, plugs, plug wires, fuel filter, everything changed. Fuel filter was clean,it still runs rough, it is at the mechanics now. They are thinking some kind of sensor issue, but dont have right manuals or are not looking in the right place. Any ideas?

That sounds like either a fuel issue; too rich, or an air leak in the manifold.
If it were an ignition issue, it woukd cut out, not run rough.

This is usually caused by a bad crankshaft postion sensor.

change your MAP sensor and clean the IAC valve

I'd get your injectors rebuilt, and tune up your injector pump. Run a little seafoam in the diesel tank, and in the oil. Should make it clear right up.

are there any fault codes present? i was looking at the fuel injection diagram on autozone.com and the only thing i can see that controls injector pulse width is the pcm. are all the injectors open for 15ms? you should also check fuel pressure. if you want to look at the diagram, go to autozone.com. register and enter you car. select repair guides, chassis electrical and the wiring diagrams

valve seals are going. when car sits excess oil gets past the valve seals then when you staRT up it burns the oil off then runs fine and no more blue smoke. It is fine to run like that had the same in a dodge caravan 1996 6cyl. ran another 100 000 km. and still ran fine got rid of it for other reasons.

Well Mike" a few things to check could be Breather on fuel tank /fuel return to tank pipe/ as pump can pump high pressure and excess has to return to tank and it sounds like yours is overfueling./take air cleaner off and all pipes and check for any thing partly blocking air flow/also check any black hoses coming from the engine breathers/going to air in take/make sure all cylinders got good compression

sounds like possible a sensor went bad or is loosly connected. O2 sensor??? Also check the air filter. Sounds like whatever it is, is making the truck run rich----that would be the black smoke.


Hope this helps

Make sure you were given the right plugs for the car (correct heat range) also check the choke plate after the car warms up to ensure the choke plate is all the way open.

Sounds like the litthe black box under the rotor button has failed. Where you sprayed the wd40. Its a position sensor to tell the cap when to fire. Used to be common on chevy but id bet thats where you need to be. Take off the cap pull the rotor and there will be two small screws golding it in. Pop it out and replace it. Could be wiring too but seing it wasnt evenmivung when it happened id bat not.