Idling/ stalling, no pedal response, weird ecu readings

[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.

Sent from my SM-N975U using Tapatalk

[ecp]

Originally Posted by ike84

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.

Sent from my SM-N975U using Tapatalk

I pmd you. I have continuity to ground on the 5v and ground for the accelerator pedal. When I measure the 5v and ground wires on the harness (one end of the multi meter in each) I get .84v and 1.20v for each power and ground circuit. If I go from signal wire to ground I get about 4.5v from each harness. There is no continuity to ground on the signal wires.

Is this telling me there’s a short somewhere in the harness? Or is the dme providing no voltage to the pedal because it’s malfunctioning?