jlag

know that after working on autos for 22 years, but my bad (since either of my Audis have ever shown any engine control problems). A6Gary (the poster who has solved many of my problems in the past) mentions meas. blk. 08 but I can find no info as to how to proceed on this on this site (own HEX-COM and Hitachi controllers in both my vehicles). Here is the situation: No vacuum to EGR valve in my 97 12V. My 96 12V will flutter with vacuum at idle at operating temp and runs great (despite the occasional detonation problem I haven't been able to figure out, yet... plenum,deto sensors, etc) so I assume there is a vacuum problem with my 97. The 97 shows codes for "insufficient flow". I will interpret this as the temp. sensor functioning correctly and check the signals at the EGR solenoid just for the sake of sanity. Looking for info as to how to test the EGR circuit (vacuum and electrical) and any insight anyone may have to this problem.The mess under the MAF sensor is a little different in the 97 as then is in the 95/96. There is a vacuum res. there that is not in my 96. The EGR Passage appears so clean it seems as though it has not sucked exhaust for the 4 years I have owned it. The code only showed up 1.5 years ago. I have cleared the code and it always shows up after system check (10-40 miles or so). I have run the vehicle with the EGR tube disconnected from the exhaust and when I open the EGR valve it sucks like crazy so I assume the passage is clear. Any info appreciated.

A6Gary

a MMS 400 or 410 - only differences between these systems should be the secondary air injection on the MMS 410/411 versions or the leak detecion pump system, which was also added to the MMS 411 system. Everything else should be the same. As far as I can see in my Bentley, the only faults for the EGR are related to electircal malfunctions, which results in an immediate lighting of the MIL. Is the EGR frequency valve -N18- functioning properly?