Presented with an Alfa Romeo 156 Twin Spark suffering with a flat spot but without any fault codes, Stephen Kasapis told GW Views how he tackled the problem job.
He said: “The Alfa had a new air flow meter, just a few hours old and I was asked to see why it had bad flat spot.
“I set up my PicoScope O2 sensor, throttle position sensor and airflow performance information data on my scan tool and went for a drive.
“Give it full throttle and the 02 went lean, so I know it needed more fuel.
“I knew it had a new air flow meter, so I checked the fuel pump and the pump flow was OK.
“The new air flow meter went to 4.454 volts, so it looks like the new air flow meter was OK.
“I’ve scoped a few Alfa 156 air flow meters before and had a look at my Pico library to confirm good air flow meters go to about 4.4 volts with the motor hot…”
This article first featured in Garage Wire Views, click here to continue reading and find out the cause of the problem.