On IDLE the rev stays at 1600 - 1800 rpm

[skiper]

Hi Guys,

I need your help .

When the engine is IDLE the rev stays at 1600 - 1800 rpm . By the time I shift to 1st gear , everything switches back to normal .

RS6 2004.

My mechanic checked the mechanical parts and everything seems in order . Here are the errors I got from VCDS :

----Engine:

Tuesday,18,February,2014,17:39:51:32264
VCDS Version: Release 11.11.3


Address 01: Engine Labels: 077-907-558-BCY.lbl
Control Module Part Number: 4D1 907 558 B
Component and/or Version: 4.2l V8/5VT G A801
Software Coding: 0005752
Work Shop Code: WSC 74500 745 00997
VCID: 2D5B176DB70A1F1
4 Faults Found:


17865 - Exhaust Gas Temp Sensor 2 (G236)
P1457 - 001 - Open or Short to Plus - Intermittent
17861 - Exhaust Gas Temp Sensor 1 (G235)
P1453 - 001 - Open or Short to Plus - Intermittent
17544 - Fuel Trim: Bank 1 (Add)
P1136 - 001 - System too Lean - MIL ON
17546 - Fuel Trim: Bank 2 (Add)
P1138 - 001 - System too Lean - MIL ON


Readiness: 0000 0000


---- Gearbox


Tuesday,18,February,2014,17:40:42:32264
VCDS Version: Release 11.11.3


Address 02: Auto Trans Labels: 01L-927-156.lbl
Control Module Part Number: 4B0 927 156 FB
Component and/or Version: AG5 01L 4.2l5VT RdW 1214
Software Coding: 00001
Work Shop Code: WSC 74500
VCID: 6CDDDA691C90D69
1 Fault Found:


17095 - Transmission Fluid Temp Sensor (G93)
P0711 - 35-10 - Implausible Signal - Intermittent


This is what I manage to find related, on the net :

17544 - Fuel Trim: Bank 1 (Add): System too Lean
P1136 - 001 - Upper Limit Exceeded - MIL ON
17546 - Fuel Trim: Bank 2 (Add): System too Lean
P1138 - 001 - Upper Limit Exceeded - MIL ON


Do these "partial" throttle additions of fuel raise any red flags as to where to start troubleshooting these codes? I reset them and they always come back after ~10-15 miles. I took a look at the visible vacuum lines, but I have to dig down behind the throttle body (http://motors.shop.ebay.com/i.html?_nkw=throttle+body) to get to those and see if any are ripped.

From Ross-Tech

Possible Solutions

Check Mass Air Flow (MAF) Sensor
Check Fuel Pressure Regulator (http://motors.shop.ebay.com/i.html?_nkw=fuel+pressure+regulator)
Check Fuel Pump
Check Intake/Exhaust System for Leaks
Check Secondary Air Injection for Leaks
Check Vacuum Lines for Leaks

Special Notes

Fuel Trim Info
When this fault is stored and external vacuum leaks are not found, less obvious problems may be present:
Check Evaporative Emission (EVAP) Canister Purge Regulator Valve (N80)
Check Brake Booster (http://motors.shop.ebay.com/i.html?_nkw=brake+booster) and Hoses
Check Electric Vacuum Pump ( If Applicable )
Check Crankcase Ventilation System for faulty components. When the PCV or Crankcase Ventilation System is faulty, vacuum is typically present under the oil cap (http://motors.shop.ebay.com/i.html?_nkw=oil+cap) and misfire faults are common.


Did anyone experience the same ?

Thanks,
Skiper.

[skiper]

one more thing : when driving , everything seems OK , no loos in power , no noise , all good.

[JSRS6]

If you are still good on power, I would say it's not a major vacuum line. But you never know. Check your n83 and check your sai system.

[skiper]

I'll have a look over there as well.

Thanks.

[lswing]

Not sure on the idle.

The EGT errors could mean they are failing. If they really are you'll get some bumps/spikes while driving as they feed the computer bad info and extra fuel gets dumped in. Keep an eye on that and replace when you can, or next time engine is out.

Here is a thread where we just discussed the G93 fluid temp sensor. I would recommend fixing when you can, maybe it would time with a gearbox fluid change. The sensor when going bad can cause poor regulation of the Torque Convertor.

http://www.rs6.com/showthread.php/26627-Back-together-after-engine-out

[4everRS]

It would be nice to see a data log in 3rd hear of blocks 3,31, and 115. In turbo mode.

[905084]

"By the time I shift to 1st"......I'm guessing it isn't related to shifting to first....maybe a SAI leak? More info please! Is it related to shifting to drive?

[skiper]

It seems we found the problem. There is a loose connection on the ABT ECU

My mechanic removed it and mounted back and it worked. After a little while it started again. He just tap/moved the connector and it worked again.
So vibration while driving can cause this randomly .

I was thinking to open the ECU and check it for any soldering problems or lose stuff inside .
Is this a good idea?

Thanks.