Can I control just fuel?
Yes, you can! In fact, we recommend this for users new to MegaSquirt EMS and users new to tuning in general. The MegaSquirt ECU doesn’t need to control spark, idle, or provide power to the sensors for fuel-only control; simply leave the corresponding wires in your wiring harness disconnected. Your MegaSquirt ECU can generally share all of the sensors with your stock PCM, except the IAT and CLT sensors. You may need to install a second set of temperature sensors in order for both ECU’s to coexist. The 420A/Neon, for instance, requires a second set of temperature sensors. We recommend the cheap, widely available and dependable GM sensors.
