SnakeTuning at 22:12, 11 June 2024

2024-06-11T22:12:59Z

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{{DISPLAYTITLE:Tech Details and Explanation}}
[[File:VR_vs_Hall_Sensor.jpg|right|thumb|Fig. 1. [[VR_SENSOR|VR Sensor]] vs [[HALL_SENSOR|Hall sensor]]]]
Honda B, D, F and H series engine distributors have three [[VR_SENSOR|Variable Reluctance Sensors]]: CKP, TDC, and CYP. The voltage at these sensors varies with engine speed in the range of ±5V to ±60V.

[[VR_SENSOR|VR Sensors]] are critical for the ECU to maintain proper engine angle tracking. Unlike modern [[HALL_SENSOR|Hall sensors]], which provide a digital output, [[VR_SENSOR|VR Sensors]] provide an analog signal whose amplitude varies with engine speed (see Fig. 1). This variability can lead to signal integrity problems at high RPM, where precision is critical to efficient engine performance.

[[File:VR_Conditioner_Board.jpg|right|thumb|Fig. 2. Honda OBD1 ECU [[VR Conditioner]]]]
To process these high voltage signals and convert them into a digital output, a daughter board is installed in the Honda ECU, also known as the [[VR Conditioner]] (see Fig. 2). A distinctive feature of this [[VR Conditioner]] is the adaptive reduction in sensitivity to the input voltage of the [[VR_SENSOR|VR Sensors]] as the engine speed increases.

This setup is good for working with [[VR_SENSOR|VR Sensors]], but creates a serious problem when emulating OEM distributor signals. Ignition accuracy and correctness are very sensitive to the input voltage to the ECU. If the voltage at the current speed is not correct, the ignition timing begins to shift or misfire.

[[File:VR_Signal_Conditioning.jpg|right|thumb|Fig. 3. Oscilloscope readings at 8000 RPM]]
The oscilloscope reading shows what happens to the output signal at 8000 RPM (see Fig. 3). The blue trace shows the output of the [[VR Conditioner]], and the yellow trace shows the input of the [[VR_SENSOR|VR Sensor]]. The correct output signal always has a load of ~50%. If the input voltage is incorrect, the load begins to increase and the ignition timing begins to shift or misfire.

To emulate the Distributor, one might consider designing an electronic device that emulates [[VR_SENSOR|VR Sensors]]. However, the characteristics of [[VR_SENSOR|VR Sensors]] and the necessity of double signal converting from digital to high voltage and back can seriously affect the accuracy of ignition timing at high speeds. Additionally, high voltage emulation would not be compatible with Standalone ECUs without additional signal converters.

After a detailed researching of the [[VR Conditioner]]'s operation, we found simpler way to solve these problems (Patent pending). It's proposed "lock" sensitivity of [[VR Conditioner]], which will allow the ECU to consistently work with low voltage signals.

Applying this simple modification allow us to generate stable trigger patterns up to '''14000 RPM''' with '''0.1 degree''' Ignition tolerance.<br clear=all>
==Modification Guides==
{{MD0_Guides}}

MD0 TECH - Revision history

SnakeTuning at 22:12, 11 June 2024