Having some engine problems, that to date my mechanic has been unable fix. Seeking any advice you can provide.
First some background.
Car was running well, but wouldn't rev past 4000rpm. Had my mechanic try to find the problem.
The error code that came up was: Code 4 Voltage at mass air sensor with hot wire circuit. Open or shorted circuit.
At this point, the mechanic looked at the upper wiring harness, and it was in bad shape. Had to order a new wiring harness for the car, which took about a month. In the meantime, most likely due to further shorts from inspecting the very bad wiring harness....the car would stutter, not rev pass 3000, and smoke was coming out the exhaust...car looked to be running rich.
So having installed a brand new upper wiring harness, the car still suffers from the same issues. Stumbling, not reving pass 3000, running rich.
When he checked the codes post installing the new harness, two codes came up. He managed to clear the injector code, but cannot clear the original code: Code 4 Voltage at mass air sensor with hot wire circuit. It will not change with the meter plugged in or not, won't clear.
Would greatly appreciate any help on this.