986 running issues

[blue583]

OK so I have a 2004 Boxster 2.7, when I bought the car it had an intermittent fault, in that the car would run for a while and then stop for no good reason, at the same time the battery kept going flat. I initially replaced the battery and subsequently fit a new alternator. This cured the flat battery issues but I was left with the engine stopping issues. I then sent the car to a local Porsche specialist who diagnosed a fault on the Mass Air flow sensor, which they replaced and at the same time serviced the car. When I picked the car up, it ran and didn't breakdown on the way home, but it felt low on power (Limp mode??). I took the car back a few days later and they said it needed a new oil air separator, but as I had already spent over £600 with them, I chose to purchase and fit it myself, which I have done. For a few days this appeared to cure the issues, but now when I start the car in the morning, it appears to be running on less than 6 cylinders and has zero throttle response and the engine management light comes on. If I immediately stop the engine and restart, the engine runs fine and the throttle response returns??, however the engine light stays on. When I check the codes on a cheap OBD-11 Dash command system it shows the following codes;
P0102 Mass or Volume Air Flow 'A' circuit low & also P1266 Unknown diagnostic code.
When I look at the Porsche fault code register the second fault comes up as - Fuel shut off function monitor?
The car has only done 54k miles and other than this issue is a nice car, but having to reset the warning light on a regular basis is annoying. As the car has had a new MAF sensor and the Oil/Air separator I am running out of ideas, can anybody help?

[Blue99]

Hi. You need to get this plugged into a proper Porsche diagnostics ~ what a cheap generic machine says is the fault code could be completely different from what a genuine Porsche diagnosis says.

[blue583]

Hi thanks for your response, the car was put on a proper Porsche diagnostic system at a Porsche specialist at the very start of this journey, do you think it needs to go back??

[JFP in PA]

Originally Posted by blue583

OK so I have a 2004 Boxster 2.7, when I bought the car it had an intermittent fault, in that the car would run for a while and then stop for no good reason, at the same time the battery kept going flat. I initially replaced the battery and subsequently fit a new alternator. This cured the flat battery issues but I was left with the engine stopping issues. I then sent the car to a local Porsche specialist who diagnosed a fault on the Mass Air flow sensor, which they replaced and at the same time serviced the car. When I picked the car up, it ran and didn't breakdown on the way home, but it felt low on power (Limp mode??). I took the car back a few days later and they said it needed a new oil air separator, but as I had already spent over £600 with them, I chose to purchase and fit it myself, which I have done. For a few days this appeared to cure the issues, but now when I start the car in the morning, it appears to be running on less than 6 cylinders and has zero throttle response and the engine management light comes on. If I immediately stop the engine and restart, the engine runs fine and the throttle response returns??, however the engine light stays on. When I check the codes on a cheap OBD-11 Dash command system it shows the following codes;
P0102 Mass or Volume Air Flow 'A' circuit low & also P1266 Unknown diagnostic code.
When I look at the Porsche fault code register the second fault comes up as - Fuel shut off function monitor?
The car has only done 54k miles and other than this issue is a nice car, but having to reset the warning light on a regular basis is annoying. As the car has had a new MAF sensor and the Oil/Air separator I am running out of ideas, can anybody help?

P0102: MAF air flow below lower limit, often a wiring issue such as a break or short.

P1266: Fuel shutoff function monitor - signal implausible

Both can be wiring issues, but PCNA had a bulletin out about re flashing the DME if the 1266 code keeps popping up.

[CarGuyNeil]

Originally Posted by Blue99

Hi. You need to get this plugged into a proper Porsche diagnostics ~ what a cheap generic machine says is the fault code could be completely different from what a genuine Porsche diagnosis says.

I gotta disagree here. A code reader is a code reader plain and simple. The issue is once you get a code you have to further diagnose it. Like someone said it could be a short in the wiring and not the actual component like a MAF. Further diagnosis is required.

Sent from my SM-N950U using Tapatalk

[JFP in PA]

Originally Posted by CarGuyNeil

I gotta disagree here. A code reader is a code reader plain and simple. The issue is once you get a code you have to further diagnose it. Like someone said it could be a short in the wiring and not the actual component like a MAF. Further diagnosis is required.

Sent from my SM-N950U using Tapatalk

Afraid I will have to disagree with you; there are quite a few codes that a "global" OBD II scanner would not even see on these cars, due to Porsche's proprietary software logic and use of programmable modules all over the car. A perfect example are a number of Tiptronic codes which cannot be seen because the Tip has its own computer module that talks with the DME. If you were to connect a generic OBD II scanner to the vehicle, you would see nothing; but connect a Porsche specific tool (PIWIS, Durametric) and up they pop.

There is a reason why shops that see a lot of Porsche's pay the price for a Porsche scan tool...................