Page Comparison

Idle

Light Throttle

Wide Open Throttle (WOT)

AFR Actual

Measure air fuel ratio of the front (pre catalytic converter) oxygen sensor. Units used are Air Fuel Ratio where 14.7 is the “ideal” mixture of fuel and air.

This lets you know how rich the fuel mixture is in the engine at any given time. Under most conditions the car will run 14.7 and then get richer under heavier load when component protection kicks in, as a richer fuel mixture provides a cooling effect for both the turbocharger and catalytic converter

• 14.7 +/- 0.2

• 14.7 +/- 0.2

• FK8

  • 13.0-11.3

Short Term Fuel Trim

(STFT)

Instantaneous correction to fuelling caused by the engine not hitting target AFR. This is based on how the car is running currently.

Based on the AFR measurement, if the ECU continually sees the car being either richer (a lower AFR number) or leaner (a higher AFR number), it will begin to add or remove (trim) the fuelling over time to compensate so the car goes back to hitting it’s target. Large numbers may indicate a leak in the intake tract where extra air is getting in. It can also indicate other physical issues with the car, or that some modification hasn’t been tuned for on your car.

• -10% - +10%

• -10% - +10%

• -10% - +10%

Long Term Fuel Trim
(LTFT)

Adjustments to fuelling the computer has learned over time are necessary for optimal engine operation/efficiency. Based on how the car has run historically

Typically based on the car continually making adjustments via STFT, these trims are added “permanently” but will gradually learn away if it sees STFT corrections in the opposite direction in that area.

• -10% - +10%

• -10% - +10%

• -10% - +10%

Ignition Timing Cyl 1-4

Ignition timing for each cylinder (1-4). This is relative to when the piston is at top dead center (TDC) of the combustion stroke.

This is the angle during the rotation of the engine (for that cylinder) at which the spark plug will fire. Numbers above zero are the number of degrees before the piston hits top dead center of the combustion stroke. While negative numbers are numbers after the piston has hit TDC. Typically as the engine works harder (load increases, more airflow/airmass/boost pressure) ignition timing advance will decrease

• -5° to 5°

• 20° to 40°

• 4° (low rpm) to 12° (high RPM) +/-2° based on fuel octane

Knock Retard Cyl 1041-4

Adjustments retarding the ignition timing (reducing ignition advance, lower ignition timing numbers) when knock has been detected

Knock has occurred, this can happen as a result of inadequate fuel octane (either bad fuel or you’re running too aggressive a map for the fuel you have), high temperatures of outside air, coolant, or intake temperature. While very minor ignition adjustments are normal, consisten large events can be very bad. Knock is actually a very aggressive detonation creating high pressure in the cylinders and can result in damage to the engine.

• 0°

• 0° to -3°

• 0° to -3°

ETC Angle Actual

Electronic Throttle Control Angle Actual. The amount of opening of the throttle body.

When you put the accelerator pedal down you’re essentially asking for an amount of torque to be produced. In response the ECU will open the throttle to allow airflow to meet the demand of this request. If you see the number go down from 100% when at full accelerator pedal down, it may be closing due to traction control coming in to play to reduce power so you can regain traction

HPFP Spill Valve Duty (Final)

Duty cycle from 0-100% of the spill valve opening.

As the high pressure fuel pump builds pressure it releases fuel and pressure via the spill valve in order to hit the pressure target. Typically if you start to hit 100% continuously, that means it is always closed, and you may not be hitting the fuel pressure or quantity target the engine needs. This can cause the engine to go lean and cause problems

• 10-20%

• 10-20%

• 10-20%

Boost Pressure

The amount of pressure over atmospheric pressure in the intake manifold. Also called Manifold Relative Pressure

Current amount of pressure in intake manifold.
Boost=Manifold Absolute Pressure-Barometric Pressure.

• -11 to 9psi

• -5 to 15psi

• 25psi peak reducing by redline.