P0301 - Please let me have your thoughts...

[teeerex]

Hi - I've done a search on the error code P0301 and nothing definative has come up.

Got the CEL light code P0301 (Cyl 1 Misfire) - when just crusing on the motorway - constant misfire when under load. The plugs and new variocam were replaced recently so don't think it will be them - plug coils wern't replaced though. Engine now makes a horrible very load ticking mechanical sound - sounds to me like a lifter has given up - is this head of ?

Car is at the dealer now (under Porsche Warranty) but just wondered if you guys have any advice ?

For example - as the Pcode clearly says 'Cat Damaging' do I have a good case for them replacing the Cat as well as the engine component ? If it is the lifter, do you think it would be wise to replace them all if the engine is out/dropped anyway ? Although a coil pack failure would obviously cause a misfire, would it create the horrible ticking noise ?

Many Thanks guys !

Richard.

Ps - 996 3.4 C4

[Loren]

After the spark plug, coil and wiring have been checked the OBD II manual suggests:

Possible mechanical causes of faults

Valve lifter chattering.

This is caused by dirt in the valve lifter.

When the Check Engine MIL lights up, a chattering valve lifter may also occur for a certain time. The DME control module registers (sporadic) misfiring at one or more cylinders. The adaptation values of areas 1 and 2 are normal.

Remedy

1. Remove lifter bores, check for damage and blowout oil passages.

2. Replace all valve lifters (engine installed).

3. During the test drive, listen for valve lifter noises.

Camshaft control badly adjusted.

The camshaft control has changed. No chattering noises occur. The DME control unit indicates misfiring for the entire cylinder bank 1 or 2. The adaptation values in area 1 differ in bank 1 and bank 2 (e.g. TRA=0.02/TRA2=0.27), the ada ptation values for area 2 are generally normal.

Remedy

1. Reset camshaft control.

2. Road test vehicle. The adaptation values should be normal.

VarioCam does not switch over completely.

Cases have occurred in which the VarioCam of one bank was mechanically faulty. In these instances, the VarioCam had not switched over completely from power to torque valve timing.

An indication of this problem is misfiring detected by the DME control module in the range of 1200 - 1500 rpm occurring in an entire bank.

The adaptation values of areas 1 and 2 are normal.

Remedy

1. Replace VarioCam.

2. Road test vehicle.

[teeerex]

After the spark plug, coil and wiring have been checked the OBD II manual suggests:

Possible mechanical causes of faults

Valve lifter chattering.

This is caused by dirt in the valve lifter.

When the Check Engine MIL lights up, a chattering valve lifter may also occur for a certain time. The DME control module registers (sporadic) misfiring at one or more cylinders. The adaptation values of areas 1 and 2 are normal.

Remedy

1. Remove lifter bores, check for damage and blowout oil passages.

2. Replace all valve lifters (engine installed).

3. During the test drive, listen for valve lifter noises.

Camshaft control badly adjusted.

The camshaft control has changed. No chattering noises occur. The DME control unit indicates misfiring for the entire cylinder bank 1 or 2. The adaptation values in area 1 differ in bank 1 and bank 2 (e.g. TRA=0.02/TRA2=0.27), the ada ptation values for area 2 are generally normal.

Remedy

1. Reset camshaft control.

2. Road test vehicle. The adaptation values should be normal.

VarioCam does not switch over completely.

Cases have occurred in which the VarioCam of one bank was mechanically faulty. In these instances, the VarioCam had not switched over completely from power to torque valve timing.

An indication of this problem is misfiring detected by the DME control module in the range of 1200 - 1500 rpm occurring in an entire bank.

The adaptation values of areas 1 and 2 are normal.

Remedy

1. Replace VarioCam.

2. Road test vehicle.

Fantastic reply Loren - Many Thanks indeed !

This site really is THE best Porsche Technical site on the net...

Richard.