[FatherAndSon]

Hi - new owner of a 2003 986 with the 2.7. My issue a series of codes and other symptoms that I think are all related. Stepping on the accelerator does nothing. The car does start up and runs. It idles rough and its revs fluctuate (800-1200). Probably runs a bit rich too. I've run a scanner and it throws all these codes.

P0103 (Confirmed) - Mass or Volume Air Flow "A" Circuit High
P0132 (Pending) - O2 Sensor Circuit High Voltage Bank 1 Sensor 1
P0138 (Confirmed) - O2 Sensor Circuit High Voltage Bank 1 Sensor 2
P0152 (Pending) - O2 Sensor Circuit High Voltage Bank 2 Sensor 1
P0158 (Confirmed) - O2 Sensor Circuit High Voltage Bank 2 Sensor 2
P0223 (Confirmed) - Throttle/Pedal Position Sensor/Switch "B" Circuit High
P1120 (Confirmed) - Manufacturer-specific code (tap to search) Throttle position sensor malfunction
P1138 (Confirmed) - Manufacturer-specific code (tap to search) Throttle position sensor 1
P1140 (Confirmed) - Manufacturer-specific code (tap to search) Throttle position sensor 2
P2135 (Confirmed) - Throttle/Pedal Position Sensor/Switch "A"/"B" Voltage Correlation

Given the majority of these codes indicate a high voltage issue, I'm thinking this is more of a centralized issue than a specific sensor being bad. Of course all of the codes are related to the throttle / air intake/exhaust system. I also found a receipt in the car from last month for installation of new O2 sensors and can confirm there are new ones under the car.I don't know the part numbers of what was installed. Electrical stuff is a weak spot of mine.

I did take the throttle body off and it was reasonably clean. Cleaned it further and reinstalled. I cleaned the MAF and replaced the engine air filter - the old one was disgusting and the foam top disintegrating. One symptom we noticed after replacing the throttle body was that after starting, pressing the brake pedal caused the engine to increase RPM a bit and then stall the engine. Another symptom is that when turning off the car the engine revs quite a bit (and sounds good) just prior to the key clicking over into off. I've swapped the DME relays and nothing changed (panel 2 positions 1&2).

I've checked multiple ground points and they are fine.

I have 3 current theories: 1 the DME may be bad and is sending greater than 5V to these sensors, 2 there is a short to power somewhere (I haven't figured out where a common short to power would be located that effects these 3 sensors), 3 the ignition electrical switch is bad (the better performance right before turning off is my reason).

Anyone have ideas? Also, anyone have the wiring diagram for the 7.8 DME showing the wiring for the MAF and Throttle sensors? I have the Bentley manual but it only has the 7.2 wiring diagram. I imagine they are similar. Thoughts on how I can further diagnose the issue?