First issue. My S4 TII engine runs really rough at ideal and is inconsistent. When cold it will occasionally stall. At 1k rpm+-100 the engine violently shacks the whole car, it feels like it will come apart any second. Over 1k the engine smoths out just fine.


My second question. The car always runs rich through out the RPM range. When I run it up to 6k+ RPM and let of the throttle it lets of a string of backfires.

The TPS sensor is in-spec and properly adjusted. The MAF and BAC sensor test Fine. I am not sure where to go from here.

 

Vacuum leak or metered air leak (such as at the TID).

As for mixture, unless you have a wideband 02 sensor, you can't really know it's rich while driving around. A catless exhaust will happily produce backfiring when you abruptly let off the throttle. You can check the dashpot on the throttle body to see if it's doing it's job. It's there to ease the throttle closed when you let off.

 

The car is definitely idling rich you can smell it. The care will occasionally back fire while idling. I have tried different methods of finding a vac leak and I cant seem to find one. I tried the starter fluid / propane method, no changes anywhere, except if I add some to the intake the idle gets worse. Oh I have also checked ignition system. timing is good and I have spark.

This may be a stupid question but what does TID stand for?

 

turbo inlet duct.

 

1. Check for trouble codes
2. Jumper the initial set connector, and set idle speed and mixture
3. Check the TPS for resistance values, dropouts, then adjust per FSM
4. Check closed loop operation
5. Backfiring during decelleration suggests the Anti Afterburn Valve may not be working
6. Check regulated fuel pressure at idle and heavy throttle, per the FSM specs
7. Backprobe the ECU connections, check voltages within range per Ch 4 of the FSM. Special attention to: AFM, intake air temp, boost sensor, barometric pressure sensor, water thermo sensor

 

ever figure out what caused this?

 

I also am curious as to what was causing the problems. Sounds a lot like my situation.

 

whats the deal, wheres the follow up posts...been a few months man.