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cheetah · 10-23-2007, 06:46 PM

Hello.

2002 Boxster S 6-speed

I suddenly am having a problem: When the vehicle is on, the accelerator pedal does not do anything (no affect on the engine at all). I know that I have the throttle-by-wire, but here is a quick background of what I have done recently…

I changed the clutch (not really a bad job at all surprisingly) and all of the sudden I am having the pedal problem. I had cleaned the throttle body while the clutch was being done, but everything seems to be in order there (took the electronics apart and all seems to look perfect). It ran fine after the clutch job for a few days.

I have the Durametric, and it comes up with the following codes:

P1219 – Porsche Code 256 – Accelerator Pedal Potentiometer
P1578 – Porsche Code 428 – Accelerator Pedal Potentiometer
P0121 – Porsche Code 117 – Throttle Valve
P1121 – Porsche Code 430 – Throttle Position Sensor
P1122 – Porsche Code 431 – Throttle Position Sensor
P0103 – Porsche Code 115 – Mass Air Flow Sensor

So I ran a real-time watch of the sensor values, and came up with the following:

Mass air flow: 48.5 kg/h
Pedal value: 30.07%
Pedal encoder potentiometer 1: 4.54V
Pedal encoder potentiometer 2: 4.54V
Setpoint throttle: 2.98%
Actual value throttle: 116.8%
Throttle position sensor: 5.00V
Throttle position sensor: 5.00V
Throttle plate angle potentiometer 1: 116.8%
Throttle plate angle potentiometer 2: -14.1%
Mass air flow sensor: 4.99V

I have tried the “normal” fixes: car on accessory for 1 minute, then off for 10 sec, and disconnecting the MAF. Disconnecting the MAF made the car run worse, so it should be fine. I also disconnected the battery for a bit to no avail.

Can this be a problem with the pedal assembly? I see the 5V readings on the TPS, is that a broken ground or something like that? It sounds like a maximum value? The throttle body is properly plugged in, and the plug shows no sign of damage. How is this wire loomed to the pedal and computer? It disappears under the intake manifold.

Any tips would be greatly appreciated. I have only had the car for a few months, but I have put a lot into it, and I want to drive it for the final few weeks of nice weather here, and this is frustrating. 

BTW, photos of the car can be seen at:

http://www.myspace.com/cheetahonline

http://www.cheetahonline.com/vehicles/boxster.html

Thanks,
Paul

10-23-2007, 06:46 PM	#1
cheetah Registered User Join Date: Jun 2007 Location: NW Indiana Posts: 156	TPS, Throttle Body, & Pedal Codes Hello. 2002 Boxster S 6-speed I suddenly am having a problem: When the vehicle is on, the accelerator pedal does not do anything (no affect on the engine at all). I know that I have the throttle-by-wire, but here is a quick background of what I have done recently… I changed the clutch (not really a bad job at all surprisingly) and all of the sudden I am having the pedal problem. I had cleaned the throttle body while the clutch was being done, but everything seems to be in order there (took the electronics apart and all seems to look perfect). It ran fine after the clutch job for a few days. I have the Durametric, and it comes up with the following codes: P1219 – Porsche Code 256 – Accelerator Pedal Potentiometer P1578 – Porsche Code 428 – Accelerator Pedal Potentiometer P0121 – Porsche Code 117 – Throttle Valve P1121 – Porsche Code 430 – Throttle Position Sensor P1122 – Porsche Code 431 – Throttle Position Sensor P0103 – Porsche Code 115 – Mass Air Flow Sensor So I ran a real-time watch of the sensor values, and came up with the following: Mass air flow: 48.5 kg/h Pedal value: 30.07% Pedal encoder potentiometer 1: 4.54V Pedal encoder potentiometer 2: 4.54V Setpoint throttle: 2.98% Actual value throttle: 116.8% Throttle position sensor: 5.00V Throttle position sensor: 5.00V Throttle plate angle potentiometer 1: 116.8% Throttle plate angle potentiometer 2: -14.1% Mass air flow sensor: 4.99V I have tried the “normal” fixes: car on accessory for 1 minute, then off for 10 sec, and disconnecting the MAF. Disconnecting the MAF made the car run worse, so it should be fine. I also disconnected the battery for a bit to no avail. Can this be a problem with the pedal assembly? I see the 5V readings on the TPS, is that a broken ground or something like that? It sounds like a maximum value? The throttle body is properly plugged in, and the plug shows no sign of damage. How is this wire loomed to the pedal and computer? It disappears under the intake manifold. Any tips would be greatly appreciated. I have only had the car for a few months, but I have put a lot into it, and I want to drive it for the final few weeks of nice weather here, and this is frustrating.  BTW, photos of the car can be seen at: http://www.myspace.com/cheetahonline http://www.cheetahonline.com/vehicles/boxster.html Thanks, Paul