Engine Controls/Electrical - MIL ON/Bank 2 Misfire DTCs
01 MIL on - R8 V10 bank 2 misfires stored after cold start
97 11 26
2026830/2
October 25, 2011.
Supersedes Technical Service Bulletin Group 01 number 11 - 28 dated June 30, 2011 for reasons listed below.
Affected Vehicles
Condition
Customer statement:
Engine warning light sporadically on, engine operation is not affected (ghost misfires).
Workshop findings:
Misfiring is logged on bank 2:
^ P0300 - misfiring recognized
P0306 - cylinder 6 - misfiring recognized
P0307 - cylinder 7 - misfiring recognized
P0308 - cylinder 8 - misfiring recognized
P0309 - cylinder 9 - misfiring recognized
P0310 - cylinder 10 - misfiring recognized
^ In most cases several cylinders are logged in bank 2.
Extended environmental conditions of the entries:
^ 2000 - 5000 rpm
^ Coolant temperature up to about 60锟斤拷C
No further entries in ECM 2.
The entries can occur while pulling away fast, with cold engine. If all environmental conditions apply, the misfire DTCS are caused by the wiring
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harness electrical interference.
Technical Background
The G28 engine speed signal wire for the slave ECM 2 (bank 2) is partly in the same wiring harness as the wires for the ignition coils on bank 2.
Figure 1. (1) J624 - slave ECM 2. (2) G28 - engine speed sender (3) D90 - RPM signal connection in engine compartment wiring harness (the engine
speed signal cable branches at this point to the master and slave engine control unit)
The routing of the wire (in the corrugated wiring cover) can be susceptible to interference.
Because of an increased ignition voltage, (e.g. engine cold + high engine speeds) the engine speed signal can get falsified.
The ECM 2 can interpret the falsified signal as misfiring.
Production Solution
Modified engine wiring harness.
Service
Note:
The engine speed signal wire to the ECM must be replaced by an externally shielded wire.
^ Create a ticket using the Technical Assistance Center System in ElsaWeb, including diagnosis log.
^ You will then receive a wiring harness kit (Figure 2). This wiring harness kit is not available through the parts system, and is furnished at no
charge to the dealer.
^ For the service installation of the wiring harness, the connection (Figure 1, 3) must be opened to access the D90 RPM signal connection.
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Spyder preparation work:
Follow all the steps of repair manual.
1. Disconnect the battery.
2. Fit the side panel protection for the R8 Spyder (VAS 6428) and the rear protector (VAS 6411).
3. Remove the oil cap, and seal the oil tank opening. This prevents the oil cap from damage during installation and removal of the air filter housing.
4. Remove the complete air filter housing.
5. Remove the left rear wheel fender liner to gain access to the ECM 2 wiring harness. In order to remove the ECM 2, the harness requires extra
slack. To provide slack, carefully unclip harness hold-downs to avoid damaging the clips.
6. Protect the area around the both ECM's with adhesive tape (particularly the lower edge of the side panel). Remove ECM 2 (J624, left side) and
disconnect ECM 1 (J623, right side) and allow both ECM's to power down for a least 15 minutes to reset all the ECM data parameters.
7. Remove sheer bolts from ECM holder.
8. Remove the complete air filter housing.
Coupe preparation work:
Follow all the steps of repair manual.
1. Disconnect the battery.
2. Remove the left and right engine compartment trim.
3. Fit the side panel protection for the R8 Coupe (VAS 6412) and the rear protection (VAS 6411).
4. Remove the oil cap, and seal the oil tank opening. This prevents the oil cap from damage during installation and removal of the air filter housing.
5. Remove the complete air filter housing.
6. Remove ECM 2 (J624, left side) and disconnect ECM 1 (J623, right side) and allow both ECM's to power down for a least 15 minutes to reset all
the ECM data parameters.
7. Remove sheer bolts from ECM holder.
Further work on Spyder and Coupe:
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1. Remove the engine speed signal wire to the slave engine control unit, from the plug, to the engine control unit. The engine speed signal wire is
located in the smaller plug, T60a (Figure 4, Arrow 1).
2. Remove the tie wrap and release the cover with a small screwdriver (push the lug upwards away from the front of the plug). Pull out the terminal
lock insert (Figure 4, Arrow 2).
3. Remove the purple engine speed signal wire from the plug. The terminal of the engine speed signal is in the brown housing element, (view from
rear) located in chamber 36. Release terminal using VAS 1978/35-16 from the front side of connector block, and gently remove wire.
SPYDER: The D90 connection point of the engine speed signal is located on the right side of the engine compartment, just in front of the heat shield
(Figure 6, red arrows).
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COUPE: The connection point of the engine speed signal is on the right side of the engine compartment around the damper mounting.
SPYDER: Mask the edge (Figure 6, blue arrow) of the heat shield with adhesive tape (risk of injury). Push back the protective hose (Figure 6, red
arrows).
SPYDER: Carefully free the clip (Figure 8, green circle) and the wiring harness at the junction of the main wiring harness (Figure 6, red arrows).
Make sure that the other wires do not get damaged.
4. Locate the D90 connection point (Figure 9, yellow arrow) of the engine speed signal. The connection point is covered with a shrink-fit hose
located at the top. At first, the three purple cables become visible as a loop (Figure 9). This loop can be pulled back in the upper section which
makes the connection point of the three wires visible.
5. Free the D90 connection sufficiently, leaving enough space for the new crimping. Cut through the original shrink-fit hose with side cutter pliers
(Figure 9, yellow arrow).
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6. Check with a multi-meter which wire (Figure 10, yellow arrows) leads to the plug of the ECM 2 (Figure 10, red arrow).
7. Cut off the affected wire on both ends (engine control unit plug and connection point) and insulate with tape. This wire is no longer needed.
8. Insert the new wire (repair kit) into chamber 36; make sure terminal is locked into housing. Reassemble the plug of the engine control unit and
secure the new harness with tie wraps.
9. Route the new harness to the connection point parallel to the engine wiring harness, and secure it with tie wraps. (Figure 11)
Note:
Make sure there is sufficient ease of movement to body parts and oil pipes (on the Spyder in the wheel arch).
Note:
The harness is designed to fit both Coupe and Spyder vehicles. On Coupes, the harness will need to be trimmed slightly in length after it is routed
and secured to the wiring harness, before making the final connection at the D90 connection point. Leave sufficient slack in harness in case slight
re-routing is necessary.
10. Crimp the two other wires, both purple, (Figure 12) with the new wire, with the crimp sleeve. Use special tool VAS 1978/1-1 yellow VAS
1978/1-2. Cover and heat up the crimping with the attached shrink-fit hose. To prevent humidity from getting in, squeeze the end (Figure 12, yellow
arrow) with pliers while hot.
11. Integrate the new connection point in the existing wiring harness, and insulate with heat-resistant tape. Push back the protective hose.
12. Perform the remaining steps in reverse order.
13. Delete both ECM DTC entries, and set throttle adaption and perform G28 adaption test drive based on the customer's typical cold start driving
profile. (Service advisor must obtain the information from the customer.)
14. Test drive the vehicle using customer cold start driving profile and observe the misfire counter, the counters should be below 3 per cylinder.
15. Check for DTC entries. Release vehicle to customer.
Note:
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The customer should be advised in rare circumstances the Engine warning light may come back with similar bank 2 misfires DTCs (ghost misfires).
Audi of America is currently working on a permanent repair solution. The ghost misfire issue has no effect on engine performance or catalytic
converter efficiency. Please contact Audi's Technical Assistance Center in these circumstances.
Warranty
Required Parts and Tools
Additional Information
All parts and service references provided in this TSB are subject to change and/or removal. Always check with your Parts Department and service
manuals for the latest information.
