auzzi3 wrote:hey guys im new to this forum and ive owned my suabru liberty 2004 turbo 2.0l for 8 months..
since ive owned it ive had a 02 sensor fault code on my ecu.. ive never had any issues and had no time to fix it..
well my issue is:
last week i was driving and suddenly began to feel sluggish and rough on idling..
the next day every time i stop it, or pull up to lights it wants to stall.. it shakes dramatically.. and when i take of its sluggish until i hit 2k revs then it drives fine..
i had the spark plugs changed,
ive had a fuel pressure test and that was fine
i had a vacuum test done.. it was fine under load but abnormal on idle..
im wondering if any one has had the same issue and if so what actions to take first as i dont want to spend large amounts of my to diagonose.
thx guys.,
teh_mechanic wrote:You say the vacuum was abnormal at idle (high vacuum point) but OK at load (low vacuum point), this and your symptoms of rough idle and stalling etc are consistent with a vacuum leak after the throttle body, or an intake tubing leak after the MAF (Mass airflow sensor) before the throttle body - either of these allows air to be sucked in after the MAF , ruining your fuel injection calculations. So that's where I'd start your diagnosis.
Have a look around the intake manifold for any obvious hoses popped off, if it's a large enough a leak to cause stalling you will probably be able to track it down by the hissing noise it makes. Next option, use a spray bottle of water and mist it around the manifold, listening for any change in RPM as the water gets sucked into the leak. Ensure your intake piping tube isn't split. Last, foolproof option for air leaks, is to have a garage with a smoke machine to smoke test the intake system.
Regarding the 02 sensor code. A vacuum leak will cause a very lean fuel condition, which can cause innactivity with the 02 sensor, enough for it to set a code. So I wouldn't just go replacing the 02 sensor yet as it may be a knock on effect of the actual problem. It will come down to the actual P code being set for the 02 sensor ie. a P0141 02 sensor heater circuit malfunction code has nothing to do with anything else, it's just very likely your 02's heater is dead, whereas a P0131 02 sensor low voltage code is often set by a good working sensor that is producing low activity because of a real engine/fueling problem, eg a lean condition from a vacuum leak.
KiDo_Tuning wrote:Issue resolved. Front passenger side intake AVCS solenoid was blocked in the open position. Had full oil flow at idle so was stuck on 52 degrees advance. No dynamic compression on one side of the engine, result was 2 cyl boxer motor at idle and poor vacuum. Uncombusted fuel was being blown out the exhaust port and causing an O2 sensor heater issue and code as the twinscroll housing prevented 'ignition' of the passenger bank until post turbo or right where the O2 sensor is.
5 minute fix thankfully and sorted
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