Reduced Power Complaints On Some BMW Engines Equipped with VANOS - Engine Builder Magazine
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Reduced Power Complaints On Some BMW Engines Equipped with VANOS

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AFFECTED MODELS/ENGINES

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E82 and E88 (1 Series) with N51, N52K and N54 engines produced from 1/2008

E90 and E91 (3 Series) with N52 engine produced from 3/2005 through 6/ 2006

E90, E91, E92 and E93 (3 Series) with N51, N52K and N54 engines produced from 7/2006

E85 and E86 (Z4) with N52 engine produced from 1/2006

E83 (X3) with N52K engine produced from 9/2006

E60 and E61 (5 Series) with N52, N52K and N54 engines produced from 3/2005

E70 (X5) with N52K engine produced from 10/2006

E71 (X6) with N54 engine produced from 1/2008

SITUATION

The “Service Engine Soon” (MIL) lamp is illuminated and a power reduction is clearly perceptible. This situation can occur after driving for some time with the engine already at full operating temperature. If the ignition is cycled, the engine then usually performs normally.

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The following faults are stored in the DME:

2A82 VANOS intake – stiff; jammed mechanically

2A87 VANOS exhaust – stiff; jammed mechanically

3100 Boost-pressure control, deactivation – boost-pressure buildup prohibited (N54 only)

CAUSE

The VANOS faults are caused by an insufficient oil pressure supply to the inlet VANOS adjustment unit. To effectively move the camshafts to the target positions in the specified time and under all engine conditions, sufficient oil pressure supply to the VANOS control pistons must always be available. When the engine operation requires that the VANOS quickly advance or retard the intake or exhaust camshaft, fault 2A82 or 2A87 may be set if the camshaft is “late,” or does not reach the target position. In this situation, engine power may be reduced and a check control message is displayed. The consequential fault 3100 can also be set in the DME fault memory as well.

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1. A mechanical restriction or an electrical failure of the VANOS solenoid and/or electrical circuit can cause insufficient oil supply to VANOS assemblies (Figure 1).

2. The oil filter cap insert may have been inadvertently removed during the vehicle’s last oil service. If this insert is not installed, it will result in non-filtered engine oil being supplied to the engine, thus possibly clogging or damaging the VANOS solenoids (Figure 1).

3. If the oil filter cap is found intact, it is possible that the
camshaft hook ring seals (3) have worn a groove into the camshaft
bearing ledge (1), causing a drop in oil supply to the VANOS unit (Figure 2).

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• Note the deep grooves worn into the intake camshaft bearing ledge by the camshaft hook ring seals (Figure 3).

• Acceptable camshaft bearing ledge – minor wear marks from the rotation of the camshaft are normal (Figure 4).

PROCEDURE

Perform all applicable test plans for the faults stored; replace parts as directed. If a root cause can be found, continue on to the following steps. If the oil filter cap insert is found to be missing, then the entire oil filter housing cap must be replaced. If excessive wear to the camshaft bearing ledge is found, it is only necessary to replace the camshaft hook ring seals and the affected camshaft bearing ledge. Refer to the appropriate service manual.

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Note: N51, N52 and N52K intake camshaft bearing ledges and hook ring seals cannot be replaced separately.

Some or all of this information was provided by the Automotive
Parts Remanufacturers Association (APRA). For more information on
technical bulletins available through APRA call 703-968-2772 or visit www.AutoBulletins.com.
figure 1 - a mechanical restriction or an electrical failure of the vanos solenoid and/or electrical circuit can cause insufficient oil supply to vanos assemblies.figure 2 -<br />1. camshaft bearing ledge<br />2. intake camshaft<br />3. hook ring seals “/><img src=Figure 4 - Acceptable camshaft bearing ledge 
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