Service

Technical Information

59/15

ENU

1X00

1

Misfiring At High RPM (59/15)

Revision:

This bulletin replaces bulletin Group 1, #59/15, dated July 2, 2015.

Model Year:

As of 2014

Vehicle Type:

911 GT3 (991)

Concerns:

Misfires at high RPM (>7,000 RPM)

Information:

•
•

Diagnostic path for fault finding in the event of the complaint "Engine misfire"
Repair scopes and required repair measures

Diagnostic path for systematic fault finding
Action
Required:

Information
The following diagnostic path will assist you to quickly and effectively diagnose "Misfires at high rpm (>
7,000 rpm)".
In particular, this involves identifying possible wear on the valve levers which usually occurs at high engine
speeds.
If misfires occur even at considerably lower engine speeds or over the entire rpm range and
depending on the fault memory entries stored in the DME control unit fault memory, the components
that are usually affected by this type of fault (spark plugs, ignition coils. injectors, etc.) must always
be checked first in accordance with the instructions provided under Guided Fault Finding in the PIWIS
Tester.
The recommended procedure for systematic fault finding in the event of the complaint "Misfires at high
rpm (> 7,000 rpm)" is described here. For greater clarity, the detailed description includes a condensed
overview of the information in the form of a table.
Customer complaint:
•

Misfires occur during full-load acceleration at high rpm (> 7,000 rpm).

•

The yellow warning message "Reduced power Driving permitted Consult a workshop" is displayed
on the multi-function display in the instrument cluster.

•

The engine warning light ("Check Engine" symbol) also comes on in the instrument cluster.

•

Engine running in limp-home mode.

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The engine warning light and warning message disappear after switching off the ignition and then
switching it back on again (ignition reset). The engine is running normally again.

Fault verification:
If these symptoms are present, the fault must be verified using the procedure described below.
Information
If misfires occur even at considerably lower engine speeds or over the entire rpm range and
depending on the fault memory entries stored in the DME control unit fault memory, the components
that are usually affected by this type of fault (spark plugs, ignition coils. injectors, etc.) must always
be checked first in accordance with the instructions provided under Guided Fault Finding in the PIWIS
Tester.
•
•

Create Vehicle Analysis Log (VAL) using the PIWIS Tester.
Read out the fault memory using the PIWIS Tester: The fault entry P0300 – Misfire totals
error together with a fault entry P0301 ... P0306 (Misfire cylinder 1 ... 6) is set in the DME
control unit fault memory.

•

Test-drive the vehicle until the fault occurs: Drive with full-load acceleration over a rpm range of
4,000 – 8,500 rpm. Observe all traffic laws. i.e. don't speed.

•

Reproduce the fault: The fault can be reproduced again - always in the same rpm range (+/- 300
rpm) - as described above.

Action Required:
1

The fault cannot be reproduced:
•

2

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There is a high probability that fault is intermittent and due to an outside influence, such as poor
fuel.

The fault can be reproduced:
2.1

Swap the ignition coil and spark plug from the "suspect" cylinder with the ignition coil and
spark plug from a cylinder that is working perfectly.
For instructions, see  Workshop Manual '282020 Removing and installing ignition coils'
and  Workshop Manual '287020 Removing and installing spark plugs'.

2.2

Test-drive the vehicle and try to reproduce the fault again under the conditions specified
above.

2.3

Then read out the fault memory of the DME control unit using the PIWIS Tester and check
whether the same fault memory entry is stored again, i.e. after swapping the ignition coil
and spark plug, the previously suspect cylinder is now working perfectly and the fault occurs
instead on the cylinder into which you installed the ignition coil and spark plug from the
cylinder that was originally suspect.

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If YES (The same fault is stored again): Remove the ignition coil from the cylinder that is
now suspect and install it again in the cylinder that was originally suspect. Leave the
spark plug in the cylinder that is now suspect. Then test-drive the vehicle again and
reproduce the fault again in order to clearly identify the component that is causing the
fault.

•

If NO (The cylinder that was originally suspect is still suspect): Remove the cylinder
head cover on the suspect cylinder bank and check the camshafts and valve levers for
visible signs of wear. For instructions, see section  Technical Information '1X0000
Checking camshafts and valve levers for wear'.

Summary:

Customer complaint
•

Misfires occur during full-load acceleration at high rpm (> 7,000 rpm).

•

The yellow warning message "Reduced power Driving permitted Consult a workshop" is displayed
on the multi-function display in the instrument cluster.

•

The engine warning light ("Check Engine" symbol) also comes on in the instrument cluster.

•

Engine running in limp-home mode.

•

The engine warning light and warning message disappear after switching off the ignition and then
switching it back on again (ignition reset). The engine is running normally again.
Fault verification

•

Create Vehicle Analysis Log (VAL) using the PIWIS Tester.

•

Read out the fault memory using the PIWIS Tester: The fault entry P0300 – Misfire totals
error together with a fault entry P0301 ... P0306 (Misfire cylinder 1 ... 6) is set in the DME
control unit fault memory.

•

Test-drive the vehicle until the fault occurs: Drive with full-load acceleration over a range of
4,000 – 8,500 rpm. Observe all traffic laws. i.e. don't speed.

•

Reproduce the fault: The fault can be reproduced again - always in the same rpm range (+/- 300
rpm) - as described above.

Fault can be reproduced

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Fault cannot be reproduced

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•

Swap the ignition coil and spark plug from
the "suspect" cylinder with the ignition coil
and spark plug from a cylinder that is working
perfectly.

•

Test-drive the vehicle and try to reproduce
the fault again under the conditions specified
above.

•

Check whether the same fault memory entry
is stored again.

•

If YES: Remove the ignition coil from the
cylinder that is now suspect and install it
again in the cylinder that was originally
suspect. Leave the spark plug in the cylinder
that is now suspect. Then test-drive the
vehicle again and reproduce the fault again
in order to clearly identify the component that
is causing the fault.

•

If NO: Remove the cylinder head cover on
the suspect cylinder bank and check the
camshafts and valve levers for visible signs
of wear. For instructions, see section 
Technical Information '1X0000 Checking
camshafts and valve levers for wear'.

•

There is a high probability that the fault is
intermittent and due to an outside influence,
such as poor fuel.

Checking camshafts and valve levers for wear
Work Procedure: 1

2

Remove cylinder head cover on the affected cylinder bank  Workshop Manual '158219 Removing
and installing cylinder head cover'.
Check camshafts and valve levers for visible signs of wear.
The following problems indicate a worn valve
lever:

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•

Rough surface on the cams of the cylinder in
question. If there is a significant amount of wear,
the contour of the tip of the cam will be "square"
and will show significant tempering colors
(blue/brown discoloration of the material caused
by high temperatures).

•

The valve lever shows significant signs of linear
wear on the contact surface to the cam  Wear

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Wear on valve lever

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on valve lever -arrow- at the edge of the hydraulic valve clearance compensating element 
Wear on valve lever -inset-. The black coating is worn down and the silver base material can be
seen.
3

Take a photo of the relevant damaged areas of the valve lever  Wear on valve lever -arrow- for
documentation purposes. Make sure that the photos clearly show the installation position of the
valve levers in question.
Also indicate the installation position of the valve levers in question (e.g. cylinder 6 – intake) or
identify the components by labelling them  Marking valve levers.
As there are 2 intake and exhaust levers per cylinder,
be sure to mark each with a number. For example:
"I 5.1" and "I 5.2" would denote the intake levers for
cylinder 5, valve 1 and valve 2.

Marking valve levers

4

References:

Attach photos to the PQIS job and be sure to attach the VAL and add a Customer Statement to the
job. After this has been done file a PTEC-TLAR.

 Workshop Manual '158219 Removing and installing cylinder head cover'
 Workshop Manual '282020 Removing and installing ignition coils'
 Workshop Manual '287020 Removing and installing spark plugs'

Repair stages and required repair measures
Work Procedure: 1

Carry out the repair scope below based on the direction from the Technical Hotline.

Required repair measures if valve lever wear is detected, depending on the technical status of the engine:
Repair scope

Action required

1

Replace engine

2

•
•
•

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Replace both cylinder heads
Replace valve drive components on both cylinder banks (camshafts, valve
levers, shims)
Replace coolant regulator

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•
•

4

Replace valve drive components on both cylinder banks:
•
•
•

2

Replace both cylinder heads
Replace valve drive components on both cylinder banks (camshafts, valve
levers, shims)
Replace camshafts
Replace valve levers
Replace shims

During repair work, also pay particular attention to the following points and carry out the
specified work.
Repair scope 1 (Replace engine):
•

After you have replaced the engine, re-program the DME control unit using the PIWIS
Tester with PIWIS Tester software version 15.700 (or higher) installed: DME control unit > 
'Programming' menu >> 'Automatic programming' function.

•

After completing the work, carry out a test drive until the engine reaches operating
temperature.

•

After carrying out the test drive, use the PIWIS Tester to create a Vehicle Analysis Log
(VAL) and select the function  ‘Data management’ > ‘VAL data return’ using the PIWIS
Tester to send it to Porsche AG.

Repair scopes 2, 3 and 4:

Parts Info:

•

During repair work, change the engine oil and oil filter and re-program the DME control
unit using the PIWIS Tester with PIWIS Tester software version 15.700 (or higher) installed:
DME control unit >  'Programming' menu >> 'Automatic programming' function.

•

See if the DME software level can be added.

•

After completing the work, carry out a test drive until the engine reaches operating
temperature.

•

After the test drive, change the engine oil and oil filter again to make sure that there are
no more residual particles of dirt in the engine.

•

Use the PIWIS Tester to create a Vehicle Analysis Log (VAL) and select the function  ‘Data
management’ > ‘VAL data return’ using the PIWIS Tester to send it to Porsche.

Part No.

Designation
– Use

Repair
scope

Qty.
1

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