Xforce exhaust = Higher idle?

[duca1991]

Hi guys, got an xforce exhaust put onto my 2011 omega Series 2.
Every now and again the idle will be a little higher when stopped. Id say 100 - 150rpm higher. Noticeable to the ear if you listen to the engine. Eventually it will fix itself and return to normal idle of around 550rpm after a few minutes of driving again. This does not occur every day. It's pretty rare to happen. Maybe once week or so driving to and from work and the driving on weekends.
I will say though and i have mentioned it on this forum that xforce sent the exhaust place i got the car done at the wrong center muffler/piping of 2.5" and the rear muffler assembly is 2.25". So the exhaust flow from the engine would increase then decrease as the rear piping is smaller correct? I'd assume this would not have any effect at all with the idle?
Or maybe this is just common as i may need a tune? any other people with an exhaust on their VE Series 2 notice this?
Thanks

 

[ducker85]

Change your oxy senors, I doubt you'll need a tune at all

 

[Marko_SJ]

Could it be ancillaries load on the engine? Ie: AC / Alt / power steer?

 

[PIR4TE]

Nothing to worry about, not to do with the exhaust, that's normal.

 

[duca1991]

Nothing to worry about, not to do with the exhaust, that's normal.

Really? what is the car actually doing in the time rpm is slightly higher? Never noticed it before the exhaust was put on. Thanks

 

[duca1991]

Well its at the lights when stopped. 90% of the time the car idles perfect just a smidge above half way. That other 10%, the rev needle would go up a fraction, 3-4mm maybe? 150rpm's id say. Mind you this is when the engine is warmed up and going

 

[PIR4TE]

I don't know exactly, you can find that out yourself using the OBD and a process of observation and elimination. What you describe is more to do with the front dress and alternator load.

 

[Munz]

Probably better that the exhaust is smaller at the rear, it would actually speed the flow as the gases cool and become denser when moving towards the outlet