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Alright, I was thinking maybe you were running into the predicted airflow table issue.
I stayed quiet after my initial suggestion of Edwin over at Powerhouse cause I didn't want to suggest any possible solutions based off of my own experience.
After installing my supercharger, I'd get a code and go into limp mode after I had drove the car around for about a month. The computer was thinking that the amount of air flowing in was way off from what it should be(I had the A&A supplied tune for the car installed) depending on how much throttle I was giving it. So going 3/4 throttle or full throttle with the supercharger obviously flows a lot more, and the computer thought that has to be wrong which would send it in to limp mode(which I would have to either shut off like you do, but after it happened 2 or 3 times I would get into the code checking area of the DIC and clear it while still rolling and it would leave limp mode). I fixed this by adjusting the predicted airflow table in HP Tuners and never had the issue again.
After dealing with it myself, it seemed to be pretty prevalent with supercharged/turbocharged C5s, as well as somewhat common with heads/cam cars since in all those scenarios you have more air flowing than originally expected.
I did remember reading about it popping up with people with an intake mod like what you said you've got, but it was much less often compared to people with Forced Induction/Cam upgrades for obvious reasons.
Long shot, but was the SLP intake added on shortly before you started experiencing this problem? I'm probably way off, but I always welcome any possible solutions myself when I'm trying to narrow down some random *** issue out of nowhere.
Interesting about the air flow issue. I bought the car used from a used car dealer in Chula Vista. Car already had the SLP on it. Test drove the car for about 15 minutes around town but no freeways. No issues. Paid the money, signed the papers, "as is final sale" no warranty. About 10 miles from the car lot heading home the car goes into "limp mode". Ah, CRAP! I have been dealing with the issue since last August.
I do not have the stock air cleaner set up. Maybe look for one on the forum to try out to see is that is the issue. Only thing I have not tried is replacing the TAC (throttle actuator control).
Interesting about the air flow issue. I bought the car used from a used car dealer in Chula Vista. Car already had the SLP on it. Test drove the car for about 15 minutes around town but no freeways. No issues. Paid the money, signed the papers, "as is final sale" no warranty. About 10 miles from the car lot heading home the car goes into "limp mode". Ah, CRAP! I have been dealing with the issue since last August.
I do not have the stock air cleaner set up. Maybe look for one on the forum to try out to see is that is the issue. Only thing I have not tried is replacing the TAC (throttle actuator control).
Worth a shot if you can find someone local to you that may have a stock intake. If I had a stock one I'd be willing to meet up with you to test it out just cause I'm curious at this point. Unfortunately I gave away the stock one I had a long time ago.
No, motor is stock but has CAI from SLP. Car has 84,000 miles on it.
I think I fixed the PM issue.
Question:
I know that you replaced the Pedal Position Switch - but you there isn't one of those throttle enhancers like "Pedal Commander" or "Solar Performance" a "Sprint Booster" installed on the Vette anywhere is there?
I know it's a long shot, but other members have had these fail on them and cause similar problems -
I am glad to hear that some of the other issues cleared up for you too -
I know that you replaced the Pedal Position Switch - but you there isn't one of those throttle enhancers like "Pedal Commander" or "Solar Performance" a "Sprint Booster" installed on the Vette anywhere is there?
I know it's a long shot, but other members have had these fail on them and cause similar problems -
I am glad to hear that some of the other issues cleared up for you too -
Thanks,Matt
Hey Matt,
Not that I know of. I do not see any additional equipment installed like that.
It never ceases to amaze me when a guy has a problem and tells his story on this site...someone is always tries to help!!!
Jerry (thread starter) is one of those guys that would give you his shirt off his back to help you. President of CSC for many years, his kindness is always evident. He has a heart of gold, always offers to help and an all-around nice guy...especially as a friend.
Sorry if I sound a tad biased, but I've known Jerry (doc) for many years and am very proud to call him my friend
So, I want to say "thank you" to all that have tried to help him...he would reciprocate if the tables were turned.
Sparky
Co-founder of The Block of Orange (with Jerry as one of its oldest members).
It never ceases to amaze me when a guy has a problem and tells his story on this site...someone is always tries to help!!!
Jerry (thread starter) is one of those guys that would give you his shirt off his back to help you. President of CSC for many years, his kindness is always evident. He has a heart of gold, always offers to help and an all-around nice guy...especially as a friend.
Sorry if I sound a tad biased, but I've known Jerry (doc) for many years and am very proud to call him my friend
So, I want to say "thank you" to all that have tried to help him...he would reciprocate if the tables were turned.
Sparky
Co-founder of The Block of Orange (with Jerry as one of its oldest members).
Sparky,
thank you for the kind words. I appreciate your friendship over the years.
Have a blessed day.
Doc
A run down of what has been done to solve the problem.
Replaced Throttle Position Sensor, no change in problem
Replaced Pedal Position Sensor, no change in problem
Replaced Mass Air Flow Sensor, no change in problem
Replaced O2 sensors, code reader said to replace, cleared code
Replaced Steering wheel sensor, code reader said to replace, cleared code. Does not set off traction control anymore
Cleaned all under-hood grounds, no change in problem
Cleaned battery cable posts, no change in problem
Sent PCM in for diagnostics, tested OK
Tested EBCM, tested OK
So, as you can see, still have not found the one problem that is causing the "limp mode".
I will next contact Power House Racing as recommend in this post and see if they have any way of fixing the problem. I have been dealing with this since last August.
When it does go into "limp mode" then I pull over, turn the car off, pull the key, open the door, wait 30 seconds and restart. I can then drive the car although the "check engine " light is on. After a few days the "check engine" light will go off. Short drips around town are pretty safe but I do not take in on the freeway of long drives.
The scanner still shows codes for what we have replaced. PCM code P1125, P2130, P2131, and then TCS code C1278 (TCS temporally inhibited by PCM) This code will go away when PCM codes are gone.
Hi Gerry,
Been a long time since I have been to the "block" runs. Don't usually come in this part of the forum all that much, but I saw this post and was curious of the issue you are having. Looking at the service manual for code P2130 it seems to also throw P2131 with it. The other code P1125 will set with those codes too if it sees an issue between the 3 APP sensors. They need to be within 13% of each other.
Looking at these codes one thing keeps standing out. APP 3 seems to be the issue that throws these codes. There are 3 wires associated with APP 3. There is a 5-volt reference, a low reference, and the APP signal itself. So the issue with these codes seems to be because of the APP 3 power, ground, or signal. I assume it throws the reduced engine power message when this happens. Question, do you lose all or just most of the throttle when this happens? I see you have replaced a lot of parts but have not touched the TAC module yet. It could be the TAC module needs to be replaced or it could be a problem in the wiring, or just needs to be reset. One thing to test before swapping out the TAC module would be to pull the connector (C1) off of the TAC and inspect for corrosion or an open in one of the pins. That module sits below the battery just like the PCM does so corrosion could be an issue. I am adding a list of info below for your reading if you wish. The pins I am curious about are pins A, E, K on connector C1 of the TAC. Those are the pins to APP 3.
The air filter issue I'm not sure if that is causing any issue. If you are getting more air in than what the car expects it will usually throw a P1514 code. Putting on the stock air filter or adjusting the values in the tune would fix that problem if it did throw that code. So if you are not seeing that code then your air filter should be fine. Also seems like you are not throwing any lean codes because of it either.
Here is some reading info. Going to add the P2130 diagnostics info.
Hope this can be of some use to you.
The accelerator pedal position (APP) sensor is mounted on the accelerator pedal assembly. The sensor is actually 3 individual APP sensors within 1 housing. Three separate signal, low reference and 5-volt reference circuits connect the APP sensor assembly and the throttle actuator control (TAC) module. Each sensor has a unique functionality. The APP sensor 1 signal increases as the accelerator pedal is depressed, from below 1 volt at 0 percent pedal travel, with the pedal at rest, to above 2 volts at 100 percent pedal travel, with the pedal fully depressed. The APP sensor 2 signal decreases from above 4 volts at 0 percent pedal travel to below 2.9 volts at 100 percent pedal travel. The APP sensor 3 signal decreases from around 3.8 volts at 0 percent pedal travel to below 3.1 volts at 100 percent pedal travel. Notice that the signal circuits for APP sensor 2 and APP sensor 3 pull up to 5 volts and the APP sensor 1 signal circuit is referenced to low reference within the TAC module.
The control module stores the DTC information into memory when the diagnostic runs and fails.
The malfunction indicator lamp (MIL) will not illuminate.
The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
If one or more APP sensor DTCs are set for a single APP sensor, the following occurs:
The control module will not command Reduced Engine Power mode.
The control module will use the remaining two APP sensors to calculate throttle response.
If certain multiple APP sensor DTCs are set for more than one APP sensor, the following occurs:
The control module commands Reduced Engine Power mode.
The APP indicated angle is limited to a predetermined value to limit the amount of throttle control.
The message center displays Reduced Engine Power.
If all three APP sensors are out of range, the following occurs:
The control module commands Reduced Engine Power mode.
The APP indicated angle is limited to 0 percent. The control module only allows the engine to idle.
Inspect the TAC module connectors for signs of water intrusion. When water intrusion occurs, multiple DTCs could be set with no DTC circuit or component conditions found during diagnostic testing.
When the TAC module detects throttle movement with a DTC P2130 set, a DTC P2131 also sets.
When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests that run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Keep this in mind when reviewing the Capture Info.
The numbers below refer to the step numbers in the diagnostic table.
This step determines if a communication condition exists.
This step isolates an internal APP sensor failure. The condition may only occur at a certain accelerator pedal position. Monitoring the APP angles for sensor 1 and sensor 2 is an accurate way of verifying the actual position of the pedal. The APP angles for all 3 sensors should be within a few percent of each other. When the pedal is at rest, the APP angle for all 3 sensors should be 0 percent. When the pedal is fully depressed, all APP angles should be 100 percent.
The APP sensor 3 has a dedicated 5-volt reference circuit. Monitoring the APP sensor 1 voltage aids in diagnosing the APP sensor 3 5-volt reference circuit. If the scan tool displays 5 volts then the circuits are OK.
When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests that run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Keep this in mind when reviewing the Capture Info.
Test for a short between the APP sensor 3 5-volt reference circuit and all other APP circuits at the APP sensor harness connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Test for a short between the APP sensor 3 signal circuit and all other APP circuits at the APP sensor harness connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Test for a short between the APP sensor 3 signal circuit and all other APP circuits at the APP sensor harness connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze/Frame Failure Records.
Hi Gerry,
Been a long time since I have been to the "block" runs. Don't usually come in this part of the forum all that much, but I saw this post and was curious of the issue you are having. Looking at the service manual for code P2130 it seems to also throw P2131 with it. The other code P1125 will set with those codes too if it sees an issue between the 3 APP sensors. They need to be within 13% of each other.
Looking at these codes one thing keeps standing out. APP 3 seems to be the issue that throws these codes. There are 3 wires associated with APP 3. There is a 5-volt reference, a low reference, and the APP signal itself. So the issue with these codes seems to be because of the APP 3 power, ground, or signal. I assume it throws the reduced engine power message when this happens. Question, do you lose all or just most of the throttle when this happens? I see you have replaced a lot of parts but have not touched the TAC module yet. It could be the TAC module needs to be replaced or it could be a problem in the wiring, or just needs to be reset. One thing to test before swapping out the TAC module would be to pull the connector (C1) off of the TAC and inspect for corrosion or an open in one of the pins. That module sits below the battery just like the PCM does so corrosion could be an issue. I am adding a list of info below for your reading if you wish. The pins I am curious about are pins A, E, K on connector C1 of the TAC. Those are the pins to APP 3.
The air filter issue I'm not sure if that is causing any issue. If you are getting more air in than what the car expects it will usually throw a P1514 code. Putting on the stock air filter or adjusting the values in the tune would fix that problem if it did throw that code. So if you are not seeing that code then your air filter should be fine. Also seems like you are not throwing any lean codes because of it either.
Here is some reading info. Going to add the P2130 diagnostics info.
Hope this can be of some use to you.
The accelerator pedal position (APP) sensor is mounted on the accelerator pedal assembly. The sensor is actually 3 individual APP sensors within 1 housing. Three separate signal, low reference and 5-volt reference circuits connect the APP sensor assembly and the throttle actuator control (TAC) module. Each sensor has a unique functionality. The APP sensor 1 signal increases as the accelerator pedal is depressed, from below 1 volt at 0 percent pedal travel, with the pedal at rest, to above 2 volts at 100 percent pedal travel, with the pedal fully depressed. The APP sensor 2 signal decreases from above 4 volts at 0 percent pedal travel to below 2.9 volts at 100 percent pedal travel. The APP sensor 3 signal decreases from around 3.8 volts at 0 percent pedal travel to below 3.1 volts at 100 percent pedal travel. Notice that the signal circuits for APP sensor 2 and APP sensor 3 pull up to 5 volts and the APP sensor 1 signal circuit is referenced to low reference within the TAC module.
The control module stores the DTC information into memory when the diagnostic runs and fails.
The malfunction indicator lamp (MIL) will not illuminate.
The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
If one or more APP sensor DTCs are set for a single APP sensor, the following occurs:
The control module will not command Reduced Engine Power mode.
The control module will use the remaining two APP sensors to calculate throttle response.
If certain multiple APP sensor DTCs are set for more than one APP sensor, the following occurs:
The control module commands Reduced Engine Power mode.
The APP indicated angle is limited to a predetermined value to limit the amount of throttle control.
The message center displays Reduced Engine Power.
If all three APP sensors are out of range, the following occurs:
The control module commands Reduced Engine Power mode.
The APP indicated angle is limited to 0 percent. The control module only allows the engine to idle.
Inspect the TAC module connectors for signs of water intrusion. When water intrusion occurs, multiple DTCs could be set with no DTC circuit or component conditions found during diagnostic testing.
When the TAC module detects throttle movement with a DTC P2130 set, a DTC P2131 also sets.
When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests that run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Keep this in mind when reviewing the Capture Info.
The numbers below refer to the step numbers in the diagnostic table.
This step determines if a communication condition exists.
This step isolates an internal APP sensor failure. The condition may only occur at a certain accelerator pedal position. Monitoring the APP angles for sensor 1 and sensor 2 is an accurate way of verifying the actual position of the pedal. The APP angles for all 3 sensors should be within a few percent of each other. When the pedal is at rest, the APP angle for all 3 sensors should be 0 percent. When the pedal is fully depressed, all APP angles should be 100 percent.
The APP sensor 3 has a dedicated 5-volt reference circuit. Monitoring the APP sensor 1 voltage aids in diagnosing the APP sensor 3 5-volt reference circuit. If the scan tool displays 5 volts then the circuits are OK.
When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests that run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Keep this in mind when reviewing the Capture Info.
Test for a short between the APP sensor 3 5-volt reference circuit and all other APP circuits at the APP sensor harness connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Test for a short between the APP sensor 3 signal circuit and all other APP circuits at the APP sensor harness connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Test for a short between the APP sensor 3 signal circuit and all other APP circuits at the APP sensor harness connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze/Frame Failure Records.
Wow! This is what I need is someone who understands a procedure to find the CAUSE of the failure in this system. I’ve read this in its entirety. Now I’m pretty good at figuring things out but this is a step above even for me. I need someone in Orange County that I can pay to do the proper diagnostics on this car. I’ve replaced enough parts just chasing symptoms.
Thank you for your help with this information, RedriderZR1. Are you available to dx this car?
Wow! This is what I need is someone who understands a procedure to find the CAUSE of the failure in this system. I’ve read this in its entirety. Now I’m pretty good at figuring things out but this is a step above even for me. I need someone in Orange County that I can pay to do the proper diagnostics on this car. I’ve replaced enough parts just chasing symptoms.
Thank you for your help with this information, RedriderZR1. Are you available to dx this car?
I do have a TECH2 so I can hook it up and see what is going on. Let me know.
Well, it appears that the saga of "Limp Mode" has come to an end. Last Sunday I spent the afternoon with SilverC54me, Gary. He has a Tech 2 scanner and he proceeded to start checking voltages on the pedal position sensor. One of the voltages was incorrect and inconsistent. He then switched out the pedal position sensor for one that he know works. This helped a little but still inconsistent voltages. As he was looking under the dash he noticed that some wires had been "spliced" in. He had an a-ha moment. After further checking the TAC wiring harness he could see further "splicing". Gary then replaced the wiring harness, with the help of Brian, from the TAC to the pedal position sensor seems to have solved the problem of someone else's hatchet job at a fix. I can't thank Gary and Brian enough and RedRiderZR1 for his technical submission. I have driven the car several times a day since then with no "limp mode" or "check engine" light. I'm gaining confidence in the car again.
This Forum can be a valuable tool from the members that belong to it. After running out of things to replace I threw up the white flag and several members had good suggestions and I appreciate you all.
See you on the road!
Doc
When finding the multiple splices in the battery area on the harness and testing the continuity between the connector ends and seeing inconsistencies that just about made it definitive that the prior splices were not good.
Ran a shielded cable from the TAC module to the pedal splicing the original connectors on to the new wire.
07-05-2021, 07:25 PM
