Nick at da Mill

Loren, Thanks for your response. Hmm. I managed to find a description of OBD Commands and Responses on pages 23-27 of http://www.elmelectronics.com/DSheets/ELM327DS.pdf. Based on this description, there is no very good reason why any scanning software would fail to report OBD TDCs as long as: 1) Porsche is reporting them in response to OBD mode 03 commands, and 2) the software reads beyond the first three (each mode 03 command reads out three DTCs). Next time the CEL lights, I'll try reading them out using native OBD commands and responses, and see what turns up. Thanks. From this description it would appear that: 1) there are only 2 variocam positions corresponding to "solenoid energized at 12V" and "solenoid not energized at 0V", and 2) there is no difference between the Variocam setting on a cold or a warm start. This will make diagnosis of mechanical solenoid function much easier. E.g., energize and de-energize the solenoid using a direct 12V source and see if the engine tone changes. This is of course assuming that there is no intermittent electrical break/short in the wiring from the ECU to the solenoid. Hmm. Does the ECU use input from the Hall effect sensor to determine this, or does it use some other means? Thanks, Nick

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

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

We have owned a low (very - 22,000 miles in 9 years) mileage 1999 2.5 liter RHD (we live in Scotland) Boxster since new. Two days ago, we drove at constant highway speeds (e.g., 80 mph) for oven an hour, before leaving the highway and coming to a stop at a red traffic light. At that point, the engine started idling very roughly (sounded like a timing problem), but with no detectable (tach. or ear) changes in rpm. After several seconds the Check Engine Light (CEL) started flashing and then came on solid. I pulled off the road, and checked the manual, which indicated I should take the car ASAP to a Porsche Service Center. We had little option but to continue on to our destination, during which the idling problem did not re-occur, nor was there any noticeable loss of power. Since we were away from home, I looked for a local Porsche dealer in the telephone book. I ended up talking to a most unhelpful service adviser (that's what his badge later said), who said I could bring it in and they would check the failure codes. Needless to say, he gave no indication of how long I would have to wait. After an hour of drinking coffee and reading newspapers, he finally fessed up that it would be at least 2 hours more. So I called a friend, who picked me up, and said I would be back the next morning. Upon picking up the car the next morning, I faced a bill for £174.49 ($321.06 this week) and the following information. 1. The PIWIS tester indicated that the car had recorded a P1531 diagnostic code. 2. They had "raised the vehicle to check the vari cam actuators as per diagnostic procedure code P1531" 3. The car required a new "actuator bank 1". Fitted cost = £617.90. I tried to get some indication from the "service adviser" as whether they had detected a hard fault or an intermittent fault, to no avail. In any case, that had reset the CEL and we drove home (more highway driving followed by red traffic lights) with no detectable rough idling or the CEL re-lighting. My gut sense is that for some reason the vari cam actuator or a solenoid (are they different ?) got a bit sticky, and didn't revert to the correct position in one instance while idling, and that this condition has not re-occurred. So I have two questions for the forum. 1. Can a visual inspection as per "2" above provide any real information on the state of the actuators? 2. Am I correct in thinking this was a single event, and can ignore it until, and if, it re-occurs?