My chevy epica will not pass emissions testing due to po171/174 error codes many people have suggested a vacuum leak could be the cause the frame by frame report showed 11.25 hg at the map is this normal
No, that should be up around 16 to 18. It appears to be losing vacuum somewhere.
June, 12, 2011 AT 9:57 PM
I have replaced the pcv valve, ihave tested the vacuum with a gauge and read in the green, ihave also sprayed maf sensor cleaner everywhere with no change in rpm, I did a second scan today and the coolant temp read 107.60f identical to the previous scan and I made sure that the engine got up to temperatureanc the coolant was circulating