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Hello!

I'm having trouble figuring out what's happening with 165 ECM. It's in a 383 Camaro, converted to $12P code.
It was running OK, but suddenly started pinging and going lean.

Log shows that TPS voltage goes from 0.6V at closed throttle to 1.3V at 100% throttle. Measured TPS voltage at ECM pin C13 is 0.55V to about 3V at WOT.
5V reference is steady at 5.02V, grounds have good continuity.
The CTS signal is also behaving strange, it shows a little high when the engine is cold (35C when engine is at about 20C), but as the engine warms up it goes up very fast, and shows 110C when I can still grab the coolant hose and lay my hand on the intake, so I guess around 50C of real temperature.
When I unplug the CTS it still shows 35C instead of -40C, and doesn't throw the code.
CTS resistance is OK, checked with the Delphi table.

Uploaded stock $6E bin to check if the $12P is faulty, but the behavior is the same.

I have opened the ECM and checked all the resistors for the CTS and TPS inputs, everything is in spec.

MAT and MAP readings show sane values, also wideband input on pin D8 works correctly.

At this moment I have ran out of ideas what's going on. Tomorrow I'll get another 165 ECM and check on it.

Thanks for any help!

Are all the PCM earths ok?

Seems that probably ADC in the ECM went bad... Swapped for another ECM and the problem is gone. Strange failure anyway.

I had a similar intermittent problem with an 808, but it read lower and caused the engine to overheat and seize as the fan did not activate. Replaced the ECU and the problem went away.