REDUCED ENGINE POWER! PLEASE HELP

[Pealewis]

Hi everyone I’m new to the group. Can anyone please tell me what I need to do with this horrible issue I am having? I have a 2011 Camaro 2SS. Intermittent I will get “reduced power” on dash and the car spits, sputters, shakes, sounds horrible and will not go over 20mph. If i shut car off and wait 10mins or up to an hour, it may drive normally again but then out of the blue I will het in it, crank up and BAM, its possessed again! Any advice? I get wayyy too many answers trying to figure out online and seems like the money will rack up if I change everything people are suggesting thanks in advance!

[InFiD3ViL]

First question...Do you have an aftermarket electronic throttle control installed, like a Vitesse or Pedal Commander? If so, disconnect/remove that and drive around for a while to see if that took care of it. Otherwise...

Do NOT change anything until you have the car properly scanned. You do not want to just throw money at a problem when a proper scan can help narrow things down dramatically. It could be many things, ie. throttle pedal, throttle body, coil, spark plug, plug wire, wheel speed sensor...etc. You should scan it because there are quite literally dozens of reasons this could be happening.

Take it to an Autozone, Advance Auto, O'Reilly's, or a local mechanic that you trust and ask if they can run a diagnostic scan on the car for you. Usually these are free at the auto parts stores, but you will get charged a diagnostics fee at a mechanics shop, although that may be worth it as they tend to have higher end, more thorough scanners. Only issue is that it may not report anything at that moment, but if you are lucky you will have stored codes. Then you can come back here and report what you found or work with a shop on repairs if it is an easy fix.

Either way, please update this thread with what info you find or actions you take. It helps out those in the future. Good luck and welcome to the site.

[Vegas Bound]

Where are you in TX? I may be able to recommend an honest shop.

[Greenhornet2]

Scan for codes, auto parts stores usually have a scanner you can use. Without a code for direction the possibilities are endless. Common issue is an aftermarket throttle body or throttle body controller as noted above.

[ElderJ]

Originally Posted by Vegas Bound

Where are you in TX? I may be able to recommend an honest shop.

I hear Scotty Kilmer is free these days. Just sitting home quarantined from what I'm seeing in his videos...

[LimaCharlie]

Agree with all comments above. First thing that came to mind for me was a bad MAF (Mass Air Flow) sensor. Checking the throttle body itself or connections is another suggestion.
Connecting a scanner to the OBDII port will answer alot of questions....

[Pealewis]

Alright, I took to AutoZone and there were two codes:
P0121-Throttle/Pedal Position Sensor A Circuit Range/Performance
P2135-Throttle/Pedal Position Sensor/Switch A/B Voltage Correlation
So, they told me I needed a MAP Sensor...?
I have also noticed my volts on my guage was dropping back to about 12-12.5, at times and my battery kept going dead about once a week. So, seeing the car still had the original battery from factory, I replaced battery. The car stopped going dead, however my volts still fall back to 12-12.5 , then will go back up to 14-14.5 when driving.. intermittently.

[JD555]

The voltage is normal. When the battery is fully charged it will drop to 12.4-12.5V and can see 15.1 when low. Mine are all over he place and only drop below 14.8-15.1v after a long long drive like over an hour or I put it on charge. After sitting all week its always 15.1v for awhile.

[DJ_BigC]

Battery voltage regulation and charging system operation is controlled via on-board control modules (ECM and BCM) along with your core components, battery and alternator.
The system voltage can vary from 12.7V-14.5V for example for no good reason aside from the vehicle wanting more or less charging output from the alternator.
Before the “start with changing or testing your battery because your vehicle has crucial electronics and blah blah blah people start chiming in with that none sense I’m telling you from 10yrs of professional experience and counting at a GM dealer a bad or weak battery is NOT your current problem. While it wouldn’t hurt to have your battery tested once this condition is diagnosed i can assure you that its not your problem.

If your battery is or has been going dead after the vehicle sits you need to perform a parasitic draw test to see if something is “staying awake” and discharging your battery and over an extended period of time causing it to be so low it doesn’t start. Next a full charging system/starting system test should be performed.. inspect to see how much amperage your starter is drawing and then load test your charging system to see if your alternator is doing it’s job.. putting a battery in your car may have put a bandaid on an ongoing problem but it doesn’t mean it didn’t fix something.

A P2135 is definitely going to give you a reduced engine power condition, it was very common in other GM models, not all vehicles have the ability to set a P2135 but GM has been plagued with this issue for years in various models with this style of DTC. A P0121 is also a throttle body DTC, the genetic scanner used to pull codes doesn’t read out the DTC description properly. If this was my vehicle.. pending it doesn’t have any other underlying issues or aftermarket accessories or tuning that modify the APP and TP voltages I would replace the throttle body assembly and perform an idle learn, I always recommend using an OEM unit for this because the aftermarket units suck and do not last.. even the performance aftermarket units are known to have TP sensor issues.
Rock auto has great prices and believe it or not most of their OEM electronics are cheaper if not the same as my cost price.

[Pealewis]

No, I do not have aftermarket parts... thanks for all the input! I did have a issue with the back blinker working/not working... noticed trunk was wet, culprit was sunroof drain... fixed that and so far nothing more issues with blinker. Waiting on clutch master cylinder now... noticed brake fluid in floor , rolling down clutch. Hopefully all the bugs will be gone soon!

[Greenhornet2]

Sounds like the throttle body to me. Voltage fluctuation is normal as stated above.

[Pealewis]

Do you think it would be worth trying to clean throttle body?? If so, is this procedure correct procedure to perform throttle/idle learn:

Key on for 3 min
Key off for 1 min
Key on for 3 min
Key off for 1 min
Start and let idle for 1 min
Go drive

[black.]

Originally Posted by LimaCharlie

Agree with all comments above. First thing that came to mind for me was a bad MAF (Mass Air Flow) sensor. Checking the throttle body itself or connections is another suggestion.
Connecting a scanner to the OBDII port will answer alot of questions....

This comment. Each time I got this was a weak MAF sensor.

[Greenhornet2]

P2135 we see a lot in the warranty world. Your throttle body is fly by wire, so for safety safe there are two sensors in it both reading the throttle position. When one of those sensors is not seeing the same position as the other sensor the computer knows that something is wrong. Being that it controls your throttle is why you go into reduced power mode. This should have nothing to do with a map, or maf sensor.