Hawley12

So my car will idle for around 5 min then randomly die. It always immediately starts right back up. Runs the same with with the IAC plugged in and without it plugged in. Any guesses?

Rusty Spokes

Hawley..what year..engine?

Hawley12

97 a6 with the 2.8

Rusty Spokes

You need to pull the fault code(s) with a VAG-COM or try a local parts store that will read OBC-2 fault codes for you for free. (most will do it free here in the USA) The OBC-2 readers may or may not be able to tell you the problem..but it is worth a try.

Your problem could be many things, a ignition switch failing..a plugged up fuel filter..a dying fuel pump..a bad electrical connector..the list goes on. Having a VCDS VAG-COM fault code helps.

If I were to guess...the ignition switch would be first..easy enough to change and get an OEM switch from the dealer...the camshaft sensor can cause this problem..the plug connector can break and hang loose and the sensor itself can become faulty..the same deal with the crankshaft sensor. quattroworld.com Forums: C4 no start

If you suspect the cam sensor (a likely suspect) you can get a new one from Hans for $16..I'm running one in my A6 now without issues.

078905161C $16 VW Audi Camshaft Position Sensor 80/90 100 A4 A6/S6 Cabriolet V6

Hawley12

Okay, so I yanked the MAF plug while the car was running and immediately dies. Odd thing is that if I start the car again with the MAF unplugged the car will idle for days. Does that mean the MAF is the issue?

Rusty Spokes

Can't really say. The engine computer will go into a fail safe mode if the MAF is disconnected when starting and operate on some standard programming without any impute from the MAF. Might be a bad MAF..or air leaks between the MAF and the intake manifold or vacuum lines.

Is the check engine light on..should be with the MAF disconnected..check and clear the codes..then see what codes come up. If you have a bad MAF..it should throw a code stored in th OBC-2

Hawley12

okay so.... Ran VCDS and cleared the codes. Plugged in the MAF let the car run till it stalled itself out. While running VCDS clocked the idle around 750 RPM and about 1.6 volts at the MAF. With the car off the MAF voltage sat around 0.6 volts. Ran a scan after it stalled and the only code it threw at me was 16486 (Mass air flow sensor - signal too low). So does this make my MAF the culprit?

Rusty Spokes

The book says you may be right. Be sure your 16486 code is not residual from unplugging the MAF..sounds like you did it correctly. Be sure the connector is good. I think the part number is 078133471A, about $150 new from FCPeuro or $60 from Hans Auto...or if you have a bone yard nearby, that MAF was used on several Audi cars with the 2.8 12v engine:

16486/P0102/000258 - Mass Air Flow Sensor (MAF/G70): Signal too Low

Possible Symptoms
Malfunction Indicator Light (MIL) ON
Loss of Power

Possible Causes
Wiring and/or Connector(s) from/to Mass Air Flow Sensor (MAF/G70) faulty
Mass Air Flow Sensor (MAF/G70) faulty

Possible Solutions
Check Wiring and/or Connector(s) from/to Mass Air Flow Sensor (MAF/G70)
Check/Replace Mass Air Flow Sensor (MAF/G70)

Hawley12

Looks like we were right! grabbed a used sensor from the junkyard for $50 (housing and intake house intact) and the car idles for days now!

Next thing on the list.....Get drivers cat over without breaking another stud on the manifold....... Thanks guys!