TPS reads 0% on Pocketlogger

[race_ready]

I only start a thread when I'm really lost. Most of the time I find what I'm looking for from just searching on here.

Has anyone come across this same situation? No matter how far I press or depress the accelerator, my logger shows 0, like it doesn't detect movement. I've tested 2 TPSs already and both have been adjusted as per steve's/RRE's instructions and measured as per Haynes to verify they're good. I've also tried resetting the ECU after adjusting it but still nothing. What else could I check?

 

[steve]

What else could I check?

Time to check the wiring. 2G TPS has four wires, +5, TPS output, IPS, and ground.
If the +5 isn't there you won't get any output.
If the ground is bad you'll get about the same voltage on the TPS output as what's on the +5 all the time and the IPS won't work.
If there is a voltage on the output but the ECU read 0 then wiring between the two of the ECU itself is damaged.

 

[race_ready]

Thanks steve. I'll check on the wiring side tonight and reply back.

 

[race_ready]

I've checked the harness:

1 - with TPS disconnected and engine off; resistance between pin 4 and chassis ground: first 1.7 then rechecked 0.0

2 - with TPS disconnected and engine on; voltage between pin 4 and chassis ground: 29.0mV

3 - with TPS disconnected and engine on; voltage between pin 1 and pin 4: 420.0mV

4 - with TPS disconnected and engine on; voltage between pin 2 and pin 4: 420.0mV

5 - with TPS disconnected and engine on; voltage between pin 1 and chassis ground: 420.0mV

 

[steve]

I've checked the harness:

1 - with TPS disconnected and engine off; resistance between pin 4 and chassis ground: first 1.7 then rechecked 0.0

2 - with TPS disconnected and engine on; voltage between pin 4 and chassis ground: 29.0mV

3 - with TPS disconnected and engine on; voltage between pin 1 and pin 4: 420.0mV

4 - with TPS disconnected and engine on; voltage between pin 2 and pin 4: 420.0mV

5 - with TPS disconnected and engine on; voltage between pin 1 and chassis ground: 420.0mV

1 - Note sure if this is OK.
2 - Doesn't seem too unusual.
3 - Are you sure? 420.0mV is 0.42v it should be close to 5v or 5000mV
4 - This should be 0v.
5 - Are you sure? 420.0mV is 0.42v it should be close to 5v or 5000mV

What lead up to this problem? Were you working on the wiring or changing an O2 sensor.?
The most common unnatural failure for a 2G ECU is a blown sensor ground.

 

[race_ready]

So almost all the measurements I took are off? I took my time, checked and rechecked the measurements each 3 times to have 1 consistent result. I'll verify again with the results you posted.

I wasn't messing with the harness before this. I wanted to log a run to see the current tune and found out that the TPS was reading a constant zero and the O2 sensor needs replacement. I started on the TPS issue first, thinking to get that out of the way but took longer than I thought it would take to resolve it so last night after checking the TPS connection I thought I might as well take off the O2 sensor but since I didn't have any anti-seize I'll only get to install the replacement tonight.

Just got to read this: blownsensorground [ECMTuning - wiki]

I'll check those mentioned there too to verify if it's indeed a blown sensor ground before I actually pull out the ECU. But last I checked IAT and coolant temp were spot on; not sure about baro; TPS read 0 and O2 was 0.04V so I'm thinking highly unlikely but worth checking to be certain. Anyone else know other related symptoms of a blown ECU sensor ground?

 

[steve]

I wouldn't focus on that being the problem. I just pointed out that it's the most common one that I see on 2G ECUs.

Double check the other sensors just to be sure, If your +5v sensor power really is 0.42v I would expect the Intake Air Temp, Baro, and MDP readings to be off too.

 

[race_ready]

I got to check the following parameters on the dsm last night:

- RPM: 950
- Coolant Temp: 186˚F
- Air Temp: 78˚F
- Air Flow: 0.58

Then compared it to a stock evo parked right next to the dsm within 3ft (same ambient condition as the dsm, waited till normal operating temp on both):

- RPM: 800
- Coolant Temp: 181˚F
- Air Temp: 96˚F
- Air Flow: 0.41

I also found out something, before checking the parameters on the dsm I did a byte timing setup test on pocketlogger and got an error stating - test halted: unstable connection. Could this be a symptom related to the TPS problem? To add, I have no CEL displays about the TPS.