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jcslocum · 06-26-2016, 03:10 AM

It's not the 02 sensors, they are reading like they should. You have a lean condition caused by false air introduced after the MAF, so not measured by the MAF. The ECU can no longer keep the mixture in range by trimming so throws a code.

1128 and 30 are the idle mixture trim code and not running at speed codes for BOTH sides of the engine. I would concentrate my looking at the center of the plenum for a cracked rubber part of loose clamp. The other thing to change is the fuel pressure regulator on the drivers side of the engine. It's a $45 part and 15 minutes to change.

Chasing these leaks can make you pull your hair out!!!

06-26-2016, 03:10 AM	#3
jcslocum Project Addicted Join Date: Aug 2015 Location: Eastern Shore, MD Posts: 623	It's not the 02 sensors, they are reading like they should. You have a lean condition caused by false air introduced after the MAF, so not measured by the MAF. The ECU can no longer keep the mixture in range by trimming so throws a code. 1128 and 30 are the idle mixture trim code and not running at speed codes for BOTH sides of the engine. I would concentrate my looking at the center of the plenum for a cracked rubber part of loose clamp. The other thing to change is the fuel pressure regulator on the drivers side of the engine. It's a $45 part and 15 minutes to change. Chasing these leaks can make you pull your hair out!!! __________________ ______ Jon 1966 912, 1976 911 1986 944, 2000 Boxster