Variocam questions

[Nick at da Mill]

I originally posted the following to my old P1531 thread, but got no response. So I'm using it to start a new thread.

The following applies to a 1999 2.5L RHD 986.

Not wishing to pay another £174.00 to read out codes and reset the CEL, I've invested in

1. An ELM 327-based USB to ODB II cable (£12.00 from China).

2. ScanTool Freeware (which allows me to read OBD II DTCs and clear the CEL).

3. The Porsche Boxster Technical Manual (£9.95 from workshopmanuals.biz)

A CEL event (flashing CEL) is now occurring occasionally when the car is restarted after a moderate (>20 minute) run. It does not occur when the car is cold, or as previously, when idling after a long run. ScanTool using the EML 327-based cable reports three DTCs (P0301, P0302 & P0303) which are mis-fires on cylinders 1-3.

So I have a number of questions.

1. Are the Bank 1 Camshaft adjustment manufacturer's codes (P1530 & P1531) available to a stock OBD tool?

E.g., does their absence in an OBD scan indicate that they have not occurred? Are they read by commands that I could add to the scan?.

2. Some of the Variocam literature describes it as "continuously-variable" valve timing. Is this really the case? For this to be

achieved, the ECU would have to vary the voltage/current to the solenoid, so as to achieve a desired valve angle as

reported to the ECU by the passage of Camshaft-attached tabs and windows through the air gap of the Hall effect sensor.

Is this really the case? If it is, then are the warm start and cold start valve angles commanded by the ECU different?

3. Do DTCs (P1530 & P1531) indicate that the ECU is not seeing the valve angle change (as reported by the Hall effect sensor)

as expected in response to solenoid input?

Thanks in advance for your answers.

Nick

Edited November 3, 2008 by Nick at da Mill

[Loren]

I originally posted the following to my old P1531 thread, but got no response. So I'm using it to start a new thread.

The following applies to a 1999 2.5L RHD 986.

Not wishing to pay another £174.00 to read out codes and reset the CEL, I've invested in

1. An ELM 327-based USB to ODB II cable (£12.00 from China).

2. ScanTool Freeware (which allows me to read OBD II DTCs and clear the CEL).

3. The Porsche Boxster Technical Manual (£9.95 from workshopmanuals.biz)

A CEL event (flashing CEL) is now occurring occasionally when the car is restarted after a moderate (>20 minute) run. It does not occur when the car is cold, or as previously, when idling after a long run. ScanTool using the EML 327-based cable reports three DTCs (P0301, P0302 & P0303) which are mis-fires on cylinders 1-3.

So I have a number of questions.

1. Are the Bank 1 Camshaft adjustment manufacturer's codes (P1530 & P1531) available to a stock OBD tool?

E.g., does their absence in an OBD scan indicate that they have not occurred? Are they read by commands that I could add to the scan?.

2. Some of the Variocam literature describes it as "continuously-variable" valve timing. Is this really the case? For this to be

achieved, the ECU would have to vary the voltage/current to the solenoid, so as to achieve a desired valve angle as

reported to the ECU by the passage of Camshaft-attached tabs and windows through the air gap of the Hall effect sensor.

Is this really the case? If it is, then are the warm start and cold start valve angles commanded by the ECU different?

3. Do DTCs (P1530 & P1531) indicate that the ECU is not seeing the valve angle change (as reported by the Hall effect sensor)

as expected in response to solenoid input?

Thanks in advance for your answers.

Nick

You had two replies in your original thread - so I am closing this thread.