Idling/ stalling, no pedal response, weird ecu readings

[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.

[blue62]

Originally Posted by ecp

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.

Just a guess on my part here but.....
With the pedal disconnected the ECU will see conflicting signals from the potentiometer and the throttle position sensor.
they work together..... you probably know this.... but as you press the gas pedal the potentiometer sends a signal to the throttle butterfly to tell it how far to open.
So my guess is if the pedal is disconnected or it has a fault the ECU sees nothing or a signal that does not make sense from potentiometer at the same time it is getting a signal from the throttle position senor. So there is a conflict....ECU's don't like that.

Wish I could be more help but trying to diagnose an issue remotely is very difficult when they are typical issues.
Your problem is far from typical....
Please keep me posted on what you find what the fix is that sort of thing.
You can PM me or just follow up on this thread.
Good luck with it.

[ecp]

Originally Posted by blue62

Just a guess on my part here but.....
With the pedal disconnected the ECU will see conflicting signals from the potentiometer and the throttle position sensor.
they work together..... you probably know this.... but as you press the gas pedal the potentiometer sends a signal to the throttle butterfly to tell it how far to open.
So my guess is if the pedal is disconnected or it has a fault the ECU sees nothing or a signal that does not make sense from potentiometer at the same time it is getting a signal from the throttle position senor. So there is a conflict....ECU's don't like that.

Wish I could be more help but trying to diagnose an issue remotely is very difficult when they are typical issues.
Your problem is far from typical....
Please keep me posted on what you find what the fix is that sort of thing.
You can PM me or just follow up on this thread.
Good luck with it.

I’ll post a follow up when I find some resolve. Poked around at some wires and traced some harnesses. Took the pot out of the car and tried testing the resistance but since there’s 6 wires it was harder to try and figure out what was what. The red and violet wire carries 5v to the gas pedal, and is also connected to the throttle body. I traced it back to the ecu so i at least know that wire is connected properly. I tried jiggling wires around while the car sputtered. The maf is hooked up to the ecu properly. If I could figure out which wires are what on the maf and throttle body I could be sure that they have correct voltage.

I’ll keep poking around at stuff after work until the new pedal and pot arrives

[ike84]

Originally Posted by ecp

I’ll post a follow up when I find some resolve. Poked around at some wires and traced some harnesses. Took the pot out of the car and tried testing the resistance but since there’s 6 wires it was harder to try and figure out what was what. The red and violet wire carries 5v to the gas pedal, and is also connected to the throttle body. I traced it back to the ecu so i at least know that wire is connected properly. I tried jiggling wires around while the car sputtered. The maf is hooked up to the ecu properly. If I could figure out which wires are what on the maf and throttle body I could be sure that they have correct voltage.



I’ll keep poking around at stuff after work until the new pedal and pot arrives

If you DM me your email, I'll send you all the wiring schematics.

My guess it's 1 of 2 things

1 - there are only a few common ground points in our cars. Multiple circuits ground to a single point. If one has become corroded (or damaged - we're you in an accident?), it could effect multiple electronics. This could also be true of wiring bundles - if you were in an accident and a bundle was pinched it could short multiple sensors.

2 - your ecu is shot

I'm hoping for 1, but Occam's razor may be pointing at the second (especially if there are signs of physical damage to the casing)

If I were you, I'd roll her to the body shop and have her totaled. Get the cash and then decide how much its worth to sort this out. That's just my 2c though.

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