Idling/ stalling, no pedal response, weird ecu readings

[blue62]

Originally Posted by ecp

I was sitting in traffic and all the sudden the car started sputtering and stalling. I barely could pull into the gas station 10 feet in front of me. I am getting zero response from the gas pedal. I pulled the engine cover while waiting for a tow and the throttle body initializes for a second but doesn’t move with the pedal. I pulled up my durametric and got
P2135 accelerator pedal potentiometer
P0123 accelerator potentiometer 1
P0223 accelerator potentiometer 2
P1120 throttle plate
P1138 throttle position sensor 1
P1140 throttle potentiometer 2
P0103 hot film MAF sensor
P0132 o2 sensor before cat
P0152 o2 sensor before cat
P0138 02 behind cat
P0158 o2 behind cat

Sounds to me like all of these are connected in a circuit that’s shorted out somewhere.
Pedal value is 30.08%
Pedal encoder potentiometers are reading 4.54v
Actual value throttle is 118% even though it’s fully closed
Throttle position sensor 1&2 are both getting 5v

I’m truly at a loss. I pulled my ecu and everything looks okay nothing obvious, I saw some weird cracking but not sure if it’s just age or what. This car is supposed to get in the body shop the end of this week and I still don’t even know if it’s going to be totaled out or not. Would love to get back running again. Any help will be greatly appreciated.

Throttle position sensor and the throttle potentiometer could be on the same circuit.
But O2 sensor and MAF with the above??? very doubtful.
I would look at a wiring schematic and see if they have a common ground.
A bad common ground for the circuits or for the ECU "could" cause your issue.

[ecp]

Originally Posted by blue62

Throttle position sensor and the throttle potentiometer could be on the same circuit.
But O2 sensor and MAF with the above??? very doubtful.
I would look at a wiring schematic and see if they have a common ground.
A bad common ground for the circuits or for the ECU "could" cause your issue.

I saw another thread where the issue looked to be pretty identical to what I’m experiencing, from 2007, they said they re established the ground from the MAF which was pin c9 on the ecu, but I can’t seem to find the pin out for the ecu anywhere, and also don’t really understand what it means exactly.
When I unplugged the MAF the car wouldn’t fire at all.

I reset the codes and the o2 sensor codes went away but everything else remained. I highly doubt this is something as simple as a fuse but I suppose I should check them just for good measure

[blue62]

Originally Posted by ecp

I saw another thread where the issue looked to be pretty identical to what I’m experiencing, from 2007, they said they re established the ground from the MAF which was pin c9 on the ecu, but I can’t seem to find the pin out for the ecu anywhere, and also don’t really understand what it means exactly.
When I unplugged the MAF the car wouldn’t fire at all.

I reset the codes and the o2 sensor codes went away but everything else remained. I highly doubt this is something as simple as a fuse but I suppose I should check them just for good measure

Interesting that your car will not start with the MAF unplugged.
Every Boxster I have heard of will run with the MAF unplugged.

You can check your MAF wiring with a Multi Meter so you could check it's ground that way.
You can also bring it up on your Durametric and look at voltage and if you know what to look for and how to compare it to other signals like throttle position you can test it's function.

You would have to look at the wiring schematics to figure out pin outs and grounds for various circuits.
Pin outs:
On the harness connection to the ecu each wire has a corresponding connecting point to the ecu.
those corresponding points are called pin outs....they are also coded similar to your fuse box...so say your looking for fuse A1 so that would be row A and 1 would be the first fuse in row A... Harness connections are set up a similar way.

Try recalibrating your E-gas (gas pedal) see if that will do anything to your throttle position codes and your potentiometer codes.
Have you every had any water get into your interior???

[ecp]

Originally Posted by blue62

Interesting that your car will not start with the MAF unplugged.
Every Boxster I have heard of will run with the MAF unplugged.

You can check your MAF wiring with a Multi Meter so you could check it's ground that way.
You can also bring it up on your Durametric and look at voltage and if you know what to look for and how to compare it to other signals like throttle position you can test it's function.

You would have to look at the wiring schematics to figure out pin outs and grounds for various circuits.
Pin outs:
On the harness connection to the ecu each wire has a corresponding connecting point to the ecu.
those corresponding points are called pin outs....they are also coded similar to your fuse box...so say your looking for fuse A1 so that would be row A and 1 would be the first fuse in row A... Harness connections are set up a similar way.

Have you every had any water get into your interior???

I had some rain water get in way over a year ago but I removed all the carped and cleaned and sealed. It was just a little water behind the seats, nothing got to the immobilizer.
It hardly runs as is because all the readings on the sensors are out of wack. The reading I’m getting on the MAF is like when it’s unplugged….. reads -40c for intake temperature. There’s gotta be some common wire for the MAF, e gas and throttle body.

I’m getting 5v on the MAF and throttle position sensor, 30% pedal value. Throttle body does not move with pedal, reads actual throttle position at 118%. I just don’t know what would make it go out sitting in traffic. It’s been dry here for quite a while, and the car was running fantastic earlier in the day

[blue62]

Originally Posted by ecp

I had some rain water get in way over a year ago but I removed all the carped and cleaned and sealed. It was just a little water behind the seats, nothing got to the immobilizer.
It hardly runs as is because all the readings on the sensors are out of wack. The reading I’m getting on the MAF is like when it’s unplugged….. reads -40c for intake temperature. There’s gotta be some common wire for the MAF, e gas and throttle body.

I’m getting 5v on the MAF and throttle position sensor, 30% pedal value. Throttle body does not move with pedal, reads actual throttle position at 118%. I just don’t know what would make it go out sitting in traffic. It’s been dry here for quite a while, and the car was running fantastic earlier in the day

The water issue:
I was more wondering if things got wet around the base of the gas pedal.
That is where the e-gas (potentiometer) is.

try recalibrating the throttle see if it has any effect.
And or disconnect the battery for an hour or so and see if the ECU will reset with default values.

5v is usually reference voltage .....the signal voltage from the ECU.

[ecp]

Originally Posted by blue62

The water issue:
I was more wondering if things got wet around the base of the gas pedal.
That is where the e-gas (potentiometer) is.

try recalibrating the throttle see if it has any effect.
And or disconnect the battery for an hour or so and see if the ECU will reset with default values.

5v is usually reference voltage .....the signal voltage from the ECU.

Never water up there. I thought it was up under the dash? Since it’s drive by wire, unless there’s multiple. The pedal feel is definitely different, I’m going to try that and also unplugging the pedal to see what readings I get.

[ecp]

Originally Posted by blue62

The water issue:
I was more wondering if things got wet around the base of the gas pedal.
That is where the e-gas (potentiometer) is.

try recalibrating the throttle see if it has any effect.
And or disconnect the battery for an hour or so and see if the ECU will reset with default values.

5v is usually reference voltage .....the signal voltage from the ECU.

Disconnected the pedal still says 30% throttle position. With my durametric I’m getting an extremely erratic MAF airflow reading. It’s running extremely rich to the point of smoke coming out of the exhaust (no cats). It bounces up and down at idle like a bad vacuum leak only it’s just sputtering and running horribly.
It seems like it’s trying to adapt to whatever the issue is but is still thrown way off

[blue62]

Originally Posted by ecp

Disconnected the pedal still says 30% throttle position. With my durametric I’m getting an extremely erratic MAF airflow reading. It’s running extremely rich to the point of smoke coming out of the exhaust (no cats). It bounces up and down at idle like a bad vacuum leak only it’s just sputtering and running horribly.
It seems like it’s trying to adapt to whatever the issue is but is still thrown way off

If the engine is not running smoothly your going to get erratic MAF air flow readings.
The more erratic the engine runs the more erratic the MAF airflow readings will be.

Did you try disconnecting the battery for a few hours???
That will force the ECU to default settings.

Then before you start it re-calibrate the E-gas.
To do that reconnect the battery.
Turn the key to the on position but do not start or crank the engine.
Wait one minute turn key off for 30 seconds.... then restart the car.
See if any of that does any good.

When you say you disconnected the pedal what exactly did you do???