[Z06] Reduced Engine Power getting ridiculous
Racer
Joined: Jul 2009
Posts: 406
Likes: 1
From: Kingdom of Bahrain
Hi
A new slant as I have been having problems with "reduced engine power"
The 1st thing I would do is to take a look at the connection at the starter motor where there is a small black cable that runs back to the alternator. It is called the fusible link, but most times it does not fuse and if you get an increase in current (electric water pump, fans, big amplifier) it gets hot, resistence goes up, and the ability to charge the battery and run the car in general is compromised.
So 1st mod is to scrap that cable altogether and connect a new 2AWG cable directly from the alternator to the post at the side of the fuse box
In doing this, you are assured that you have continuous power to all circuits at all times
Maybe.....................
A new slant as I have been having problems with "reduced engine power"
The 1st thing I would do is to take a look at the connection at the starter motor where there is a small black cable that runs back to the alternator. It is called the fusible link, but most times it does not fuse and if you get an increase in current (electric water pump, fans, big amplifier) it gets hot, resistence goes up, and the ability to charge the battery and run the car in general is compromised.
So 1st mod is to scrap that cable altogether and connect a new 2AWG cable directly from the alternator to the post at the side of the fuse box
In doing this, you are assured that you have continuous power to all circuits at all times
Maybe.....................
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
A few months after I bought my 08 new, the reduced engine power thing went on a few times in a couple of days. Limped to the dealership during one of the episodes and they diagnosed it as a bad pedal/tps. They ordered a new unit, changed it and it has been fine over a year later.
Thread Starter
Instructor
Joined: Aug 2004
Posts: 147
Likes: 0
From: Florida
Yah. Took the throttle body apart, and found that the blade had some burrs on it, and some scratches on the intake portion. Took some steel wool and some sandpaper and put it back together. Problem hasn't returned since then. Looks like that fixed it.
Paul
Paul
Le Mans Master
Joined: May 2007
Posts: 6,013
Likes: 18
From: Havre De Grace, MD/Apalachicola, FL
Nice to know. Hope that is a permanent fix.
Instructor
Joined: May 2009
Posts: 211
Likes: 3
From: Dallas, TX
P2138 Throttle Pedal Position Sensor / Switch D/E voltage correlation.
Usually this is a throttle pedal issue, there is only a few things that should set this code a short in the circuits, bad engine ecu, or accelerator pedal position / throttle pedal position sensor.
I'll be surprised if cleaning the throttle body fixes it.
Usually this is a throttle pedal issue, there is only a few things that should set this code a short in the circuits, bad engine ecu, or accelerator pedal position / throttle pedal position sensor.
I'll be surprised if cleaning the throttle body fixes it.
Last edited by 1988Bullitt; Jan 18, 2010 at 10:31 AM.
Racer
Joined: Jan 2010
Posts: 293
Likes: 2
From: Atlanta Georgia
The code you're getting is for APP2 HIGH VOLTAGE. Just from the code description and criteria for setting it, you can conclude a few different things,
1: The 5 volt reference to APP2 is good. Without it, you can't have high voltage.
2: The sensor return circuit from the APP to the PCM is good. If there were high resistance in the circuit, you could not have high voltage.
3: The connectors/connections are good. Again, with high resistance in the connections, you won't have high voltage on that circuit.
4: It cannot be the tune. Conditions for setting the code require the voltage to be over 4.5 volts for more than 12.5 seconds. You cannot tune that in or out.
5: It's not a TPS/ETC problem. That would have it's own separate set of codes.
The best part about OBD2 diagnostics is, for alot of the codes, they're so descriptive, with a good understanding of the systems, you can deduce alot. This particular one, it is safe to deduce that you need a pedal assembly.
1: The 5 volt reference to APP2 is good. Without it, you can't have high voltage.
2: The sensor return circuit from the APP to the PCM is good. If there were high resistance in the circuit, you could not have high voltage.
3: The connectors/connections are good. Again, with high resistance in the connections, you won't have high voltage on that circuit.
4: It cannot be the tune. Conditions for setting the code require the voltage to be over 4.5 volts for more than 12.5 seconds. You cannot tune that in or out.
5: It's not a TPS/ETC problem. That would have it's own separate set of codes.
The best part about OBD2 diagnostics is, for alot of the codes, they're so descriptive, with a good understanding of the systems, you can deduce alot. This particular one, it is safe to deduce that you need a pedal assembly.
Last edited by jatolbert; Nov 12, 2010 at 12:25 AM.
Racer
Joined: Jan 2010
Posts: 293
Likes: 2
From: Atlanta Georgia
P2138 Throttle Pedal Position Sensor / Switch D/E voltage correlation.
Usually this is a throttle pedal issue, there is only a few things that should set this code a short in the circuits, bad engine ecu, or accelerator pedal position / throttle pedal position sensor.
I'll be surprised if cleaning the throttle body fixes it.
Usually this is a throttle pedal issue, there is only a few things that should set this code a short in the circuits, bad engine ecu, or accelerator pedal position / throttle pedal position sensor.
I'll be surprised if cleaning the throttle body fixes it.
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Racer
Joined: Jan 2010
Posts: 293
Likes: 2
From: Atlanta Georgia
Racer
Joined: Jan 2010
Posts: 293
Likes: 2
From: Atlanta Georgia
Hi
A new slant as I have been having problems with "reduced engine power"
The 1st thing I would do is to take a look at the connection at the starter motor where there is a small black cable that runs back to the alternator. It is called the fusible link, but most times it does not fuse and if you get an increase in current (electric water pump, fans, big amplifier) it gets hot, resistence goes up, and the ability to charge the battery and run the car in general is compromised.
So 1st mod is to scrap that cable altogether and connect a new 2AWG cable directly from the alternator to the post at the side of the fuse box
In doing this, you are assured that you have continuous power to all circuits at all times
Maybe.....................
A new slant as I have been having problems with "reduced engine power"
The 1st thing I would do is to take a look at the connection at the starter motor where there is a small black cable that runs back to the alternator. It is called the fusible link, but most times it does not fuse and if you get an increase in current (electric water pump, fans, big amplifier) it gets hot, resistence goes up, and the ability to charge the battery and run the car in general is compromised.
So 1st mod is to scrap that cable altogether and connect a new 2AWG cable directly from the alternator to the post at the side of the fuse box
In doing this, you are assured that you have continuous power to all circuits at all times
Maybe.....................
