Idling/ stalling, no pedal response, weird ecu readings

[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???

[ecp]

Originally Posted by blue62

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???

I unplugged the potentiometer under the dash. I unplugged the battery for a bit and it looked like all the fuel trims reset, but still no difference, when I try to clear the codes with durametric they do not go away. That tells me either wiring issue or issue with the ecu, but don’t know where to look.

Should I start testing the grounds to throttle body and MAF? Can I use continuity with my multimeter? I think I found a couple diagrams showing the ground wire for each, and in theory I should have continuity to any ground on the car? The plugs on the ecu look good no corrosion and they’re not loose. I tried wiggling them around to see if a wire on the plug is loose but no resolve. Seems like the wire for the MAF is on the third plug of the ecu from what I’ve found.
Maybe I can test for continuity between the ground on the maf and throttle body as well?

[blue62]

Originally Posted by ecp

I unplugged the potentiometer under the dash. I unplugged the battery for a bit and it looked like all the fuel trims reset, but still no difference, when I try to clear the codes with durametric they do not go away. That tells me either wiring issue or issue with the ecu, but don’t know where to look.

Should I start testing the grounds to throttle body and MAF? Can I use continuity with my multimeter? I think I found a couple diagrams showing the ground wire for each, and in theory I should have continuity to any ground on the car? The plugs on the ecu look good no corrosion and they’re not loose. I tried wiggling them around to see if a wire on the plug is loose but no resolve. Seems like the wire for the MAF is on the third plug of the ecu from what I’ve found.
Maybe I can test for continuity between the ground on the maf and throttle body as well?

You said your gas pedal felt different.
My guess is that your E-Gas potentiometer has gone south. "But it is just a guess"
there are numerous wires that go to it.
I think your best bet at this point is to take it to a shop that is well schooled in electrical issues with theses cars.

Continuity testing by it's self is not that reliable....... this is why I say that.
Wires are made up of multiple strands.
It only takes a single strand to show a connection "continuity"
So all the strands in a wire can be broken except one... that wire will test as good because it shows "continuity" on the single strand.
But the wire "circuit" will not function because there will be to much resistance from the broken strands.

Continuity test are only reliable if the wire is completely broken "no continuity" or used in conjunction with resistance testing.

So again I think you need a shop schooled in electrics specific to theses cars.
Sorry I can't be of more help.

[ecp]

Originally Posted by blue62

You said your gas pedal felt different.
My guess is that your E-Gas potentiometer has gone south. "But it is just a guess"
there are numerous wires that go to it.
I think your best bet at this point is to take it to a shop that is well schooled in electrical issues with theses cars.

Continuity testing by it's self is not that reliable....... this is why I say that.
Wires are made up of multiple strands.
It only takes a single strand to show a connection "continuity"
So all the strands in a wire can be broken except one... that wire will test as good because it shows "continuity" on the single strand.
But the wire "circuit" will not function because there will be to much resistance from the broken strands.

Continuity test are only reliable if the wire is completely broken "no continuity" or used in conjunction with resistance testing.

So again I think you need a shop schooled in electrics specific to theses cars.
Sorry I can't be of more help.

I appreciate all the input. It does feel different. And it started inching in traffic, it revved way up when I gave it a little gas and then started missing and died. I ordered a used pedal with potentiometer. I’m wondering if it’s still in “limp” mode with the pedal disconnected because it’s getting zero reading and that’s what it defaults to now. I hope I can get it by Thursday. I’m going on a trip and still have the body shop and insurance to deal with. Just want to drop it off and not have to worry about these headaches.
Fingers are crossed that the pedal and a hard reset of everything will correct it.