the_duke

SAI is temperature activated. If ambient temp is high enough it won't run.

jcman

When the engine is at idle "only" in closed loop and cold the SAI system is activated until the pre-cat O2 sensors see normal levels, this can happen way before the engine is at operating temperature by the CTS.

This all started with the MPI control units MMS 400/410/411 beginning in 1996 when Audi ditched EGR's, since then our Motronic ME 7 ecm carries the same order with the SAI.



audi_nicoya209

what is the function of the N112 valve and the N249 (if the 2.8 atq has one)

jcman

The N112 is a solenoid type valve that when energized allows vacuum to actuate "open" the combi-valves, part of the SAI system.

The N249 is a solenoid type valve that is used to actuate the DV "Diverter Valve" on 2.7 turbo engines.

Airbag

the solonoid and vacuum lines are easy to check and are right up top. the vacuum lines sit on top of the intake manifold area and are prone to rotting. check those first.

audi_nicoya209

I'll definitely check all the lines because my pump is definitely running i can hear it. By any chance what size hose is the hose that comes out of the combi valves and then all the lines in general?

audi_nicoya209

So I replaced all my vacuum lines and got rid of the check engine light and finally passed my emissions inspection with flying colors this afternoon. Thank you to everyone who contributed to this thread it is much appreciated

jcman

Excellent!

I'm going to crack open a cold one this evening and raise it high over your victory! Plus it's Friday.

audi_nicoya209

haha thanks dude 👍