Car running rough

[riley]

I need some help diagnosing a problem. Car was running well and then suddenly began running poorly. Wondered if it was a blown head gasket at first. Had a friend look at it and he unplugged the MAF and the car ran better, but still rough. We switched back to the stock MAF and a Turbotweak chip to no avail. No trouble codes, all the sensors are in the right range. Except the O2 sensor is reading about 200 mV and 9.5:1 at idle. The exhaust is black. There is some smoke coming from the engine bay, passenger side.

We've swapped out the MAP, MAF, chips, O2 sensor, coil and module, IAT, cleaned the IAC, new spark plugs and wires. Everything we could think of aside from the crank sensor.

Appreciate any thoughts you may have.

 

[ES1]

Might check and see if you are getting fire to all cylinders.
You can also pull the injector harness off the injector one at a time. You will be able to hear the change in the engine when you do this.
Are you sure all the MAF are good?

 

[riley]

Thanks for the suggestions. Pretty sure the MAFs are good, tried a new sensor as well. We used a coil tester to make sure we were getting a spark.

The engine doesn't want to idle on its own without stalling. If you open the throttle a bit it runs albeit roughly. According to Directscan the injector duty cycle is about 5% at idle.

 

[TurboV]

Sounds like the MAF sensor. Tap on it whille the car is running with the handle of a screw driver and see if it stumbles..

 

[riley]

We'll give that a shot next and see what happens. Thanks!