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Technical Information

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1X00

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Misfiring at High RPM (59/15)

Information
This Technical Information replaces the previous Technical Information dated September 2, 2015.
•

Reason: Different repair concept used if there are visible signs of wear on camshaft
and/or valve levers

If visible signs of wear are found on the camshaft and/or valve levers during the fault finding steps
described in this Technical Information, the engine must always be replaced.
This means that the various repair stages used previously depending on the date of manufacture of the
respective engine will no longer be used.
Please note this procedure may lead to a diagnosis of a replacement engine. Standard
warranty policy and procedures must be adhered to with respect to major assembly
replacement.
You will find details of the procedure in the description below.
Vehicle Type:

911 GT3 (991)

Model Year:

As of 2014 up to 2016

Concerns:

Engine malfunction (Misfiring at high rpm)

Situation:

•
•

Diagnostic path for fault finding in the event of the complaint "Engine malfunction"
Required repair measures

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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:
•

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

•

The yellow warning message "Reduced power Driving permitted Consult a garage" 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:
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.

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•

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.

•

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

•

Test-drive the vehicle until the fault occurs: Drive with full-load acceleration in 3rd gear (manual
gate) over a rev range of 4,000 – 8,500 rpm

•

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

Action Required:
1

2

The fault cannot be reproduced:
•

There is a high probability that the malfunction is not caused by wear on a valve lever. Another
component must be checked in order to determine the cause.

•

If necessary, contact Technical Support in order to decide what to do next.

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.
•

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'.

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Summary:

Customer complaint
•

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

•

The yellow warning message "Reduced power Driving permitted Consult a garage" 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

•

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.

•

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

•

Test-drive the vehicle until the fault occurs: Drive with full-load acceleration in 3rd gear
(manual gate) over a rpm range of 4,000 – 8,500 rpm.

•

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

Fault can be reproduced

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Fault cannot be reproduced

•

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.

•

There is a high probability that the
malfunction is not caused by wear on a valve
lever. Another component must be checked
in order to determine the cause.

•

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

•

If necessary, contact Technical Support in
order to decide what to do next.

•

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

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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'.

•

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:

3

•

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 valve lever
wear on the contact surface to the cam  Wear
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.

If there are visible signs of wear on the camshaft and/or valve levers:
Take photos and replace the engine
3.1

Take photos of the damaged areas on the camshaft and/or valve levers  Wear on valve
lever -arrow-. Make sure that the photos clearly show the installation position of the valve
levers in question.

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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.

3.2

Document the photos together with the
vehicle analysis log and the engine
number of the vehicle in the related PQIS job.

3.3

Replace engine and re-program DME control
unit. For instructions, see  Technical Information '1X0000 Repair measures'.
Marking valve levers

References:

 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 measures
Work Procedure: 1

Replace engine  Workshop Manual '100119 Removing and installing engine'.

2

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.

3

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

4

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 PCNA.

Parts Info:
Information
To simplify the ordering process, the additional parts required for replacing the engine have
been grouped together as a repair kit under one part number.
Overview of the parts to be ordered for replacing the engine:

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Part No.

Designation
– Use

Qty.

9A1 100 975 EX

 Replacement engine

1 ea.

000 043 303 61

 Engine repair kit

1 ea.

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The parts included in the repair kit and details of where they are used are listed here for your information.
There is no need to order the parts individually unless additional individual parts are required.
Part No.

Designation
– Use

Qty.

000 043 303 61

Engine repair kit