I have an 05 Astra with idle problems, it starts up fine but after bringing the revs up it either stalls or hiccups once it returns to the usual idle speed.
Engine is Z18XE.
I've cleaned the throttle body and used Launch to open the throttle wide open and it is operating fine. Checked for air leaks etc...
Tested the MAF and it seems to be working fine. Reaching roughly 4.8V upon acceleration.
After a string of tests it finally produced a fault code; P0170 Fuel trim too rich.
Next step was to check the Lambda sensors, and as somewhat of a newbie to oscilloscopes and diagnostics I believe that my waveform isn't exactly what I should be seeing. I've used the acupuncture probes and gone into the grey wire of both zirconium dioxide sensors and I should be expecting a very clear switching from 0.1-0.9V roughly on pre-cat and a steady 0.1-.0.2 post cat if everything is working correctly. Pre-cat I have a large "block like" pattern at the high end of the 1V scale. I'm not sure if this is simply telling me it's way too rich, or is it in fact a failure in the sensor?
I've put the emissions tester in the exhaust and at idle I have as following:
9.372% CO, 9.5% COc, 8.4% CO2, 744 HC and 0.7 Lambda.
So it is running rich...
I've also tested fuel pressure at the rail at idle and it's just below 4bar which according to Autodata is within tolerance of 3.6-4 bar.
I'm not sure where to go next, any ideas would be much appreciated.
Thanks in advanced, Brad.