performance – Macbook Pro 2011 – CPU Thermal Throttling

Macbook Pro (13”, late 2011);
Memory 4GB;
Processor 2,4Ghz Intel;
Graphics Intel HD;
Mac OS Sierra 10.12.6;
Power adapter original 60W (got 2 of them);
Battery new.

This issue has been reported before (Macbook Pro 2011 slow) and appeared to be solved since the Mac was working fine for three days. Before the problem only occurred when the battery was nearly 100% charged with the power adapter connected.

Here is what happens now:

• When the battery is charged more than ~50% while having the power adapter connected, the mac gets very slow. The activity monitor is showing kernel CPU usage of up to 500%, the system is running at ~93%, user load is normal =/< 8%. All other processes are normal. The activity monitor is not showing any processes with excessive energy consumption. Memory consumption is normal too. The CPU goes back to normal immediately when on Battery only, with the Power Adapter disconnected. Within minutes after connecting the power adapter the game starts all over again.
• No difference with different power adapters.

I performed a couple of different tests, all done without third party hardware, nothing connected, even not LAN. Software which had kernel extensions in Library/LaunchDaemons before, was completely removed.

Checking the System load while on Battery: pmset -g sysload

• 2025-01-02 15:34:49 -0300
• combined level = OK
• user level = OK
• battery level = OK
• thermal level = Great

Checking again while on Power Adapter with the CPU throttling: pmset -g sysload

• 2025-01-02 15:36:19 -0300
• combined level = Bad
• user level = OK
• battery level = Great
• thermal level = Bad

Checking the thermal log while on Battery, no problems:
pmset -g thermlog

• Note: No thermal warning level has been recorded
• Note: No performance warning level has been recorded
• 2025-01-02 15:56:26 -0300 CPU Power notify
• CPU_Scheduler_Limit = 100
• CPU_Available_CPUs = 4
• CPU_Speed_Limit = 100

Checking again while on Power Adapter with the CPU throttling:
pmset -g thermlog

• Note: No thermal warning level has been recorded
• Note: No performance
  warning level has been recorded
• 2025-01-02 15:58:25 -0300 CPU Power
  notify
• CPU_Scheduler_Limit = 40
• CPU_Available_CPUs = 4
• CPU_Speed_Limit = 29

After these tests I installed TG Pro. The temperatures are absolutely normal all the time. The fan speed is adjusting well to CPU loads. The fan and outlet are also clean. I was adjusting the fan speed to max when the problem occurred, but this made no difference.

It appears to me that there is a (false) temperature signal from somewhere causing the CPU throttling although all the temperatures recorded as well as the sensors are normal conform to TG Pro. It is also not possible to sense any excessive heat when touching the Mac.

The only way to get the CPU back to normal is disconnecting the Power Adapter and the system load drops immediately. Also the SMC reset is solving the problem for the moment until the battery is charging again with the Power Adapter connected.

Another strange thing I noticed is the System Report showing a negative mA reading while on battery power only.

In Safe Mode the Mac is still working fine again under any power supply condition. Anyhow after shutting down from Safe Mode and rebooting the problem comes back.

From my prospective this is either a hardware problem (sensor / connection) or a system management software problem. I would like to be able to determine either one.

Therefore a couple of questions:

1. Why are there no thermal and performance warnings recorded
   although the performance is down and the thermal level is bad when
   the problem occurs?
2. How can the negative mA reading of the battery
   being explained?
3. Did anybody experience this problem, CPU
   throttling only while battery being fully charged and using power
   adapter?
4. Is there any other Terminal commands or third party apps
   to retrieve more power management and SMC information, especially on other
   temp sensors?
5. Is it worth doing a clean boot stick reinstall of
   Sierra?
6. Any other suggestions to identify the root cause of the
   problem?

Thank you in advance.