Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Ignition Control
The ECM calculates the optimum ignition timing based on pre-programmed maps and information from the following sensors:
- CKP sensor
- CMP sensors
- MAF sensor
- ECT sensor
- Electric throttle TP sensor
- Knock sensors
- TCM
- Ignition coils.
During engine starting the ECM uses a fixed ignition setting. When the engine has started and the vehicle is being driven, the ECM adjusts the ignition timing accordingly using other parameters such as engine speed, load and temperature.
Once the engine has reached its normal operating temperature, the ECM monitors the signals from the knock sensors. If any of the cylinders produce knocking, the ignition timing for that cylinder will be retarded until the knocking has stopped. The ignition is then gradually advanced back to the normal timing or until the knocking re-occurs.
The ECM uses information from the TCM to provide torque limitation during transmission shifts. The ignition timing is adjusted to momentarily reduce the engine torque output to give a smooth transmission shift and reduce load on the transmission.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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