carbon covered spark plugs

Hi guys,

I have an 88 hb and last week starting acting funny. First the check engine light came on and it blink once meaning a problem with the oxigen sensor. The car didn't run strong anymore and it idle rough, like it wanted to turn off. I reseted the ECU three times and the check engine like still came on. So I replaced the Oxygen sensor.

Then, the car still idle rough and it was running weak. Also, replace the spark plugs and and when I remove them to check them, all of them were covered in carbon. And the exhaust smells really bad.

Please, post if you know what could be causing this. Thanks

Did you check your timing?

I figured out what the problem was. The hose coming from the map sensor to the intake manifold had a crack. I couldn't see that before because the crack was facing the fire wall.