Idling Issue - S8

[Gearcon]

Hi all,

Just bought an 2006 S8, so new to the forum and learning quickly about the car.

Help is needed with the following: when the car comes upto temperature it begins idling erratically.

Geeting the following errors from Vag-Com:

Bank 1: Camshaft B (Exhaust)
P0014 - 004 - Retard Setpoint not Reached (Over-Advanced)

Bank 2: Camshaft B (Exhaust)
P0024 - 004 - Retard Setpoint not Reached (Over-Advanced)

Is this pointing to the solenoid operated control valves for both exhaust camshaft adjusters, not doing their job correctly.

Also do these swich in when upto temperature, getting the fault at low rpm readings, approx 600 RPM.

Thank for any help and advice.

Joe

[Guest 2]

Welcome to VWAF

Hope these diagnosis links help?

16398/P0014/000020 - Ross-Tech Wiki (http://wiki.ross-tech.com/wiki/index.php/16398/P0014/000020)

V10 engine - strange code - A8 Parts Forum (http://forum.a8parts.co.uk/showthread.php?t=6215)

[Gearcon]

Hey thanks,

Hope it's not the actual physical adjusters at the back of each camshaft, a pain to change plus £££.

Bought the car with an ill engine, basically oil starvation followed by a bit of a row inside the engine, then it eat itself, as you'll see below.

Found a part of an oil ring in the inlet track and piston bits in the intake manifold.

So bare block and heads in from germany and rebuild.


2240922410224112241222413




http://www.youtube.com/watch?v=ExUWtzK4ZoU

[Gearcon]

Seem to have found the problem, so detailing it for anyone who has a similar issue.

Symptoms:

Idling becomes erratic when engine reaches temperature and tends to cut out.

Suspect:

One of the hydraulically actuated mechanical camshaft adjusters that sit at the back of each of the camshafts. In this instance Exhaust Camshaft, Bank 1.

Diagnosis:

Using Vag-Com, engine temperature below 90C, looking at master ECU (J623) under controller 01-Engine and Measuring Group 90, which relates to the "Continuous Camshaft Adjustment Exhaust, Bank 1 (Drivers Side)"

Adjustment Specified = -22 KW; Adjustment Actual = -22 to -17 (erratic). So below temp the ECU is controlling position relatively good, engine idle is ok. Should not be erratic though.

When engine upto temperature, i.e. over 90C and the thermostat opening (Group 130, 3rd Column, Thermostat Duty Cycle > 0) Group 90 now gives:

Adjustment Specified = -22KW; Adjustment Actual = 0 to 9 (erratic). So ECU having a hard time to control position, not achieving setpoint. Engine idling erraically. Also Engine fault code being put out: "Bank 1: Camshaft B (Exhaust) - P0014 - 004 - Retard Setpoint not Reached (Over-Advanced).

Also when upto temperature the engine has entered close loop control.

The ECU undertakes a self test on the variable camshaft adjuster system for each camshaft: Group 96 "Continuous Camshaft Adjustments Banks 1 & 2 Exhaust, Short Trip," "Test Results Bank 1" = "System Not OK" - So definitly a problem


Ok, so theory: when the engine is below temp the ECU can deal relatively ok with setting the camshaft position, Bank 1 Exhaust, engine running open loop control strategy. When the engine comes upto temperature it enters closed loop control, the lambda sensor on this bank is throwing out a high figure (Group 33) relative to bank 2. The engine see's the lambda is way off and tries to control this bank best it can to sort it. Due to mechanical fault with Bank 1 Camshaft Adjuster it cannot and plays with timing/fueling and hence the erratic idling, when at temperature.


Verification: Removed the rocker cover, Bank 1. Found physical play on the exhaust Camshaft, can rock it left and right. This is not the case with the inlet cam, very solid.

So hence all pointing to the Physical Mechanical Adjuster. Changed the solenoid control valve before all this to rule it out too.

Will change the Mechanical adjuster and report back.