BA2 Turbo Rough Idle

[clevo400]

Hey All,

 

Sometimes when cold starting the BA2 Turbo it will crank then when I let the key go it sounds like a big pop coming from the throttle body or air box.

 

When cranking again it will start and run on like 5 cylinders. If I turn it off I have to wait a few minutes or if I drive to work for a few minutes it shakes and then smooths out.

 

Hooked an OBD Reader on and it didn't have any fault codes but I noticed the O2 sensor was sitting straight on 0.9V and not fluctuating. When it drives normally it does fluctuate from 0.1 to 0.9V.

 

Does a faulty O2 sensor pull a code or do I just replace it with a NGK. Already cleaned Throttle Body and replaced Ryco Fuel Filter, Delphi Coils and NGK Plugs.

 

Hitting 195,000km.

Edited 27/10/24 12:41 PM by clevo400
New data

[k31th]

The Oxygen sensor should throw a code, but there could be a separate issue preventing it from making it to the OBD system... I would definitely try replacing the Oxygen sensor in the situation you've described.

[Tom Tucker]

Popping and missing sounds more like cam sensors or crank angle sensor to me. The wiring on these sensors is prone to failure over time. They should throw a code though.

Could also be coils.

[xr6tForMe]

Rough idle, but driving ok could be intake manifold gasket.

Can test by squirting some butane at different points where the intake manifold is mounted to the head while the car is idling.  If idle changes, its sucking in the gas instead of just air.

Can also test disconnecting wiring to each coil while it is running to see which cylinder is not running right. 

If you disconnect a coil and it runs worse, that cylinder was working.

 

Is idle always bad, or only sometimes?