Petrol Injection Sensors Overview

How The Map Fits

SFI meters each injector in firing order from the ECM. Air mass, crank and cam position, throttle demand, coolant temperature and exhaust oxygen set pulse width. Idle is 725 ± 50 rpm. This page is a field overview, not an inlet-manifold or full rail strip.

Sensors At A Glance

• MAF: lives on the air cleaner outlet, reports air mass and intake temperature so the ECM can size the fuel shot. A choked element or leaky trunking after the meter skews mixture. Element service is separate from this article.
• CKP: inductive pickup on the timing-chain cover, reads the crank disc. Without it there is no sequential injection timing. Sensor-to-bracket 8 Nm, bracket-to-block 21 Nm. Renew the O-ring when the sensor is out.
• CMP: one on each bank at the right-hand end of the head, triggered by the inlet cams so the ECM knows bank and stroke. Bolt 6 Nm. Oil the O-ring lightly on refit.
• Throttle demand: 2.0 uses a potentiometer on the throttle spindle (TPS screws 7 Nm). 2.5 and 3.0 use a pedal position sensor; the ECM then drives the throttle motor. Housing to manifold 10 Nm if that joint is opened.
• Oxygen sensors: upstream (and downstream where fitted) keep the cats in the right window. Thread torque 40 Nm. Exhaust heat and loom chafe kill them as often as age.
• VCT oil control solenoids: meter oil to the inlet cam phasers under ECM command from load and speed. Solenoid bolt 10 Nm after the relevant cam cover is off. Cover strip is an engine job.

Coolant inlet pipe bolts are 25 Nm and outlet 10 Nm when those pipes are disturbed for sensor or housing access. Fuel rail bolts are 10 Nm. Do not probe ECM pins. A stored fault and a live data trace beat unplugging sensors one by one.