O2 Clamp

An O2 clamp (AKA O2 Signal Modifier) is frequently used in with piggyback fueling solutions attached to a stock ECU. During the transition from Closed/Open Loop fueling or transitioning into boost, the stock ECU may attempt to decrease fueling because it's unaware that a piggyback/AFPR is attempting to add more fuel at the same time. This is often described as "lean tip-in" - causing a lean fueling condition (that can damage engines), and for many MSM owners, a bog/hesitation when driving.

When the O2 clamp detects boost, it will send an altered signal to the OEM ECU, so that the stock ECU does not decrease fuel delivery.

  • An O2 clamp is not necessary when using standalone ECUs, as they completely control fueling.
  • Installation includes a vacuum line tap connected to the internal boost pressure sensor and two wires to intercept an OEM ECU signal.
  • Some electronic piggybacks no longer require an added O2 clamp, as they may already have them integrated into the unit or programmed to piggyback to account for this. Confirm if an O2 clamp is compatible or recommended by the specific vendor.

Installation is an easy few wires and safe (no lean tip-in when entering boost) solution is an O2 clamp. Typically they use a pressure switch that is connected into a vacuum line. When the switch sees a certain amount of boost (usually .5psi), they trigger the o2 clamp to trick the ECU into thinking that no extra fuel is being added. This will ensure that all your added fuel will be there when demanded upon and you will get rid of the stumble.

Available via:

User: Olderguy @ Miataturbo.net

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