Had this a couple days now Recovered in by Rac erratic revs
Its 2009 zafira b z16xe1 45k on clock
No fault codes present
It initial revs high at roughly 1900 rpm then settles to 1400rpm
Once revved idle is the erratic bouncing from 9-1300rpm
I've found that If aircon is switched on it idles nicely at 800 ish rpm
Initial thoughts where vac leak fuel trims show to be ok
Short - 0 and long 8.6 when its revving erratically
Map sensor seems ok intake 39kpa when idling ok with aircon jumps about from 40-52 when revving erratically
Coolant temp is reading ok
Throttle position. 4%
I've removed cleaned throttle body on the off chance
And still the same
Went round intake manifold with Brake cleaner to check revs don't change
Removed oil cap and still same
O2 obviously erratic too when engine is erratic
When aircon pressed an revs stabilise
Sensor 1 reads 742.2Mv and sensor 2 reads 232.4 mv for a short period
Then rear shoots up to 722.6 mv and stays reading that for a short period before going lean and reading 195.4mv
Fuel trims read 0 when aircon on
No unusual noises
vac guage Teed in
Engine steady initial start up idle but at 1500rpm
Showing 20inhg
Snap throttle goes to 0 and down to 25inhg before settling back to 20inhg
Once hunting starts the vac guage also bounces between 15-18 inhg
Snap throttle still same as previous
Aircon turned on a steady idle at 800rpm
Vac gauge reads 18 inhg
Would this point to mechanical engine issues?
Valves or what ever ?
Bit lost where to go next or should I say point lads in direction as I'm only collecting tool box tomorrow but still be nice to help the lads sort it