REM Gauge Readouts Summary

Here is a summary of all the available readings that have been programmed into the Renix Engine Monitor.

Renix Engine Readings

MAP = Manifold Absolute Pressure sensor

The MAP sensor reads the absolute (actual) pressure inside the intake manifold.

Note: An Absolute Pressure is not zeroed out, so a lower number means lower pressure.
Remember that the Earth’s Atmospheric Pressure is 29.9”Hg (14.7psi) at Sea Level, so a running engine will read less pressure than the atmosphere.

Note: Only one value is reported for the MAP sensor input. This reading can be converted into sensor voltage or actual sensor pressure, but they will always follow each other perfectly.

– Engine Off (~30”Hg at sea level) This should read Atmospheric Pressure
– Engine Idle (< 15”Hg) A healthy engine should pull decent low pressure at idle
– Open Throttle (~15-30″Hg) Opening the throttle should raise the pressure

VAC = Relative Manifold Vacuum.

This gauge calculates the Manifold Relative Vacuum in the intake manifold instead of the Absolute value above. This is a normal vacuum gauge that has been zeroed to the earth’s atmosphere and shows a negative pressure, which we call a vacuum.

Note: This is calculated from the MAP and Baro reading: Vacuum = [Baro] – [MAP]

– Engine Off (~0”hG), The engine should show ~0 vacuum when off
– Engine Idle (> 15”hG) A healthy engine should pull decent vacuum at idle
– Open Throttle (~0-15″Hg) Opening the throttle should lower the vacuum

Baro = Barometric Pressure before Engine Start.

This gauge shows the MAP pressure before the engine start and is used by the ECU to calculate fuel needs. This reading will not change when engine is running.

Note: This reading is reported directly from the ECU.

To test the accuracy of the MAP sensor, you can use an Air Pressure at Altitude calculator. Input the Baro reading, current outside air temp, and see if the altitude roughly matches your current areas altitude.

EX: BARO = 14.0 PSI, AIR = 72ºF. Estimated Altitude reading = 1,377 ft.

ºFWT = Water Temperature

Shows Temperature of the Engine Coolant from the Temperature Sender in the lower drivers side of the engine block.

Note: This may read different from the temp gauge in the dash because it is a different sender. The dash sender is located on the rear driver side of the cylinder head.

– Engine Cold (~Outside Air Temp) This should be close to the Ambient Air
– Engine Warm (~180 – 220ºF) 210ºF is proper Engine Operating Temperature

ºFIA = Intake Air Temperature

Shows Temperature of the incoming air inside the Intake Manifold. This sensor is important for proper engine fueling calculations since Renix is Speed Density tuned.

– Engine Cold (~Outside Air Temp) This should be close to the Ambient Air
– Engine Warm (~90-130ºF) This reading should be hotter than Ambient Air

RPM = Revolutions Per Minute

Shows how fast the Engine is spinning based off the Crankshaft Position Sensor (CPS). The engine has to spin faster than 300 RPM for the sensor to register. 0 RPM when cranking could point to a faulty sensor.

Note: This reading is actually the spark timing gap that the ECU sends to the ignition module. So if you see RPM, you should be getting spark, atleast to the ICM anyway.

– Engine Off (0) There should be no reading when off (may persist after engine stops/stalls)
– Engine Idle (~600-900) Proper Idle should be around 750 RPM
– Engine Redline (5000) Engine speed should not go over 5000 RPM

VLT = Battery Voltage

This displays the current voltage of the Battery.

Note: On 4.0L this may be the Fuel Pump/o2 Relay Circuit which will normally read 0v after 3 seconds when the engine is off. This will read correctly when the engine is running.

– Engine Off (~12.4-12.8) A healthy battery will rest around 12.6 Volts
– Engine Idle (~13.5-14.5) A healthy Alternator should supply 13.5-14.5 Volts

vO2 / mVo = Exhaust Gas Oxygen Sensor Voltage

Shows the Oxygen content in the Exhaust Gas Stream reported from the Oxygen (o2) Sensor. For proper Closed Loop operation, this reading should constantly swing between a high and low value.

Note: A faulty oxygen sensor will not move at all and usually pegs lean. This is the main cause of poor fuel economy and open loop conditions.

Note: For Renix, is it HIGHLY recommended that you use an NTK/NGK o2 sensor over a Bosch for a proper sensor swing!

4.0L: (0v to 5v signal)
– (< 2.5v) Exhaust is reading RICH, Oxygen content low
– (> 2.5v) Exhaust is reading LEAN, Oxygen content high

2.5L (0mV to 1000mV signal)
– (< 500mV) Exhaust is reading RICH, Oxygen content low
– (> 500mV) Exhaust is reading LEAN, Oxygen content high

A/F = Air / Fuel Ratio

Shows approximate Air / Fuel Ratio of the exhaust gas stream as reported by the o2 sensor. This is useful to see how efficiently your engine is burning fuel.

For better accuracy and o2 tuning, a Wideband o2 sensor driver/gauge can be hooked up to the REM and will show instead of the stock o2 conversion.

Note: This is an REM only reading and is very approximate since narrow band o2 sensors are not absolutely accurate or consistent. This is only used to put a “Real” number to the otherwise meaningless o2 voltage, and should not be used for real tuning needs.

– (13-14) Exhaust is showing Richer, more power but less fuel economy. Too rich may cause carbon build up.
– (14-15) Exhaust is showing Stoic, best complete fuel burn for emissions
– (15-16) Exhaust is showing Leaner, less power but more fuel economy. Too lean may cause knock.

EX = Exhaust Gas Status

ECU reported value that Indicates whether the Exhaust is Richer or Leaner than Stoichiometric (14.7lbs of air to 1lb of fuel)

Note: On older updates, this reading will not update in open loop.

– (LEAN) Exhaust Mix has more Air than 14.7:1
– (RICH) Exhaust Mix has more Fuel than 14.7:1

vHT = Oxygen Sensor Heater Relay Voltage

Shows the Voltage that the Oxygen Sensor Heater Relay is supplying to the Oxygen Sensor. This reading may read 0v under WOT Open Loop Conditions. Battery voltage is required for the o2 sensor to heat up and work properly.

Note: This is an REM reading from a built-in Voltage Divider that can safely read from 0 to 18V DC.

– Engine Off (0v) The ECU will provide power for 3 seconds, then stop
– Engine Running (~12-14v) Voltage drop may cause less than battery from the Relay

LP = Exhaust Loop Status

Indicates the Loop Mode that the ECU is currently in. This will read OPEN when the engine is cold and should switch to CLOSED when the oxygen sensor is ready. A faulty o2 reading will prevent closed loop and use more fuel to run.

– (OPEN) ECU Ignores o2 Sensor and runs off a base fuel curve
– (CLSD) ECU uses o2 Sensor to obtain proper air/fuel ratio
– (DECEL) ECU enters fuel cut-off mode during hard Deceleration(>1,200 RPM & Closed TPS)

EGR = Exhaust Gas Recirculation

Displays if the ECU is allowing the EGR Solenoid to open or close the EGR Valve.

– (ON) EGR Valve is Open, usually during Closed Loop
– (OFF) EGR Valve is Closed, usually during Warm-Up, Idle, WOT, and Decel

TPS = Throttle Position Sensor

Shows how far the Throttle Plate is open in Percent. The TPS should have a range between 17% and 94%, and should be adjusted for the engine to idle correctly.

Note: Only one value is reported for the TPS sensor input. This reading can be converted into sensor voltage or actual sensor percent, but they will always follow each other perfectly.

– Closed (~14-18) The TPS should rest at 17% when closed, adjust if necessary
– Wide Open (~94) The TPS will NOT read up to 100% under normal operation

TH = Throttle Position Mode / Switch

4.0L: Shows what mode the ECU is reading the TPS as.
2.5L: Shows Closed Throttle Switch in the ISM, and a WOT Switch on some models.

– (CLSD) ECU reads TPS as completely closed
– (PART) ECU reads TPS as Partially Open and operates normally
– (WOT) ECU reads TPS as being Wide Open Throttle and will go into Open Loop

IAC = Idle Air Control Valve Turns (4.0L)

On 4.0Ls, idle speed is controlled by an IAC stepper which provides extra air to the throttle body.

This is an REM only reading that shows the estimated number of IAC rotations open or closed, with the count starting at 128. The IAC is a stepper motor, which requires the ECU to send individual pulses to rotate. Each pulse is indicated by an open or closed arrow, even if the counter has hit a limit.

Note: The ECU does not have position feedback of the IAC so it does not know if the valve is stuck, fully opened, or closed. The ECU will still continue to send pulses to try and correct the idle speed, which could cause the count to eventually hit a limit.

Note: The datastream will tell us if the IAC is currently being commanded open or closed, but not exactly how many pulses were sent so this number is only an estimate. The ECU can send multiple step pulses much faster then the datastream updates, and they will be missed by this count.

– (< 128) The IAC is being commanded closed more often
– (> 128) The IAC is being commanded open more often
– If the number continues to rise or fall at idle without stopping, the IAC is either at fault or their is an air/fuel imbalance that is preventing the IAC from fully controlling idle speed.

ISM = Idle Speed Motor Offset (2.5L)

On 2.5Ls idle is controlled by an Idle Speed Motor (ISM) which physically opens and closed the throttle body plate.

This is an REM only reading and shows the estimated TPS Offset that the ISM is extending. The ISM is a DC motor which spins open or close to control idle. This can be seen by the TPS changing at idle.

– (0) No Idle Offset Commanded
– (> 0) TPS% Amount of idle offset commanded

PSW = Power Steering Pressure Switch (2.5L)

This is an REM only reading. On 2.5Ls, idle compensation is used when high Power Steering Load is detected to help the engine from stalling.

– (OFF) Power Steering Pressure Low
– (ON) Power Steering Pressure High

IGN = Ignition Timing Advance (ºBTDC)

Shows how much Ignition Advance the ECU is applying in Degrees Before Top Dead Center. Engine Knock will lower this reading.

– Idle (10-20º) Advance is low during Idle
– Throttle (30-40º) Advance will rise with throttle input

RTD = Ignition Timing Retarding Amount

REM only readings. Shows how much Ignition Retarding the ECU is removing from the base IGN value. A higher retard reading means more timing is being pulled back.

– (0) No Ignition Retarding applied
– (> 0) Amount of Retarding applied due to Engine Knock

KNO = Knock Sensor (4.0L)

Shows how many units of Engine Knock the ECU is detecting. This reading will be near 0 at idle and rise with RPM

Lower Driver Side of Engine Block, sends an electrical signal to the ECU if Engine Knock is measured.

– Engine Idle (~ 0) No Engine Knock is detected
– Engine 2500 RPM (~10-100) A little knock with RPM increase is normal

mS = Injector Pulse Width (mS)

Shows the length of time the ECU is energizing a fuel injector for in Millisecond which relates to how much actual fuel is being requested.

Note: This will read much lower on 2.5L’s due to a single TB Injector

– Engine Idle (~4-8) Should be low when engine is running properly in closed loop
– Engine Raised RPM (~6-22) Will vary on how much fuel is needed.

– Engine Idle (~1-2) Should be low when engine is running properly in closed loop
– Engine Raised RPM (~2+) Will vary on how much fuel is needed.

Cold Enrich = Injector Cold Enrichment Value (mS)

Shows the additional length of time the ECU is energizing a fuel injector for in Millisecond which relates to how much actual fuel is being requested. When the Engine is cold, the ECU will dump fuel to help heat up the Catalytic Converter.

– ( > 1) Engine is very cold and using lots of additional fuel
– ( < 1) Only slightly more fuel is used to help engine run, closed loop will be attempted
– ( 0 ) No Additional Enrichment is being added.

%DC = Injector Duty Cycle

This shows the percentage of time the Injector is energized compared to the time it takes the engine to complete one cycle. A properly sized Injector should never be above 80% DC.

– Idle (~2-10%) Low RPM means less fuel and a longer engine cycle
– WOT (< 80%) At Max RPM the Injectors shouldn’t be on for more than 80%

SYN = Distributor Fuel Sync Signal (4.0L)

Reads the sync signal generator in the distributor to determine proper firing order by locating piston 1’s compression stroke. This may not update when engine is off.

Note: Due to the Flywheel only showing piston pairs (1/6, 2/5, 3/4), the sync signal is required to determine which pair is on a compression stroke and set it’s firing order.

Note: The REM displays an animation when Sync change is detected. Exact speed or direction are not important, just as long as it’s spinning.

– (+) Piston 1 is on Compression Stroke
– (-) Piston 1 is on Exhaust Stroke

ST = Short Term Fuel Trim (Adaptive Offset)

This is a value used by the ECU to monitor the instantaneous amount of fuel required to run properly. This value is an offset of the LT Fuel Trim and will change with current Engine Conditions.

Note: This value will only update in Closed Loop, otherwise the base value of 128 is shown. If a limit of 0 or 255 is hit for too long, closed loop will fail and go back to open.

– (< 128) The ECU needs less fuel then base to run properly
– (128) The ECU is using the Base Fuel Curve (Open Loop)
– (> 128) The ECU needs more fuel then base to run properly

LT = Long Term Fuel Trim (Adaptive Gain)

This is a value used by the ECU to monitor the average fuel required to run properly. This value doesn’t usually change after the ECU has adapted to the fueling requirements.

Note: If the ECU can not properly hold Closed Loop for an extended period of time, the base value of 128 will not update.

– (< 128) The ECU needs less fuel on average then base to run properly
– (128) The ECU is using the Base Fuel Curve
– (> 128) The ECU needs more fuel on average then base to run properly

A/C = Air Conditioning Select Signal

Displays if the ECU is detecting the A/C Select Signal to activate the A/C Compressor Clutch. The A/C Mode Select Switch and A/C Low Pressure Switch must both be closed for this to be displayed.

– (ON) A/C Select Signal is active
– (OFF) A/C Select Signal is not active

REQ = Air Conditioning Request Signal

Indicates if the A/C Evaporator Thermostat Temperature Switch is at an acceptable range for A/C use.

Note: The A/C Select Signal must be active for the Request Signal to work.

– (YES) All conditions met for A/C operations
– (NO) One or more conditions are not met for A/C operations

ACCL = Air Conditioning Clutch Signal

Indicates if the Air Conditioning Clutch Relay is being requested.

– (ON) A/C Clutch Signal is active
– (OFF) A/C Clutch Signal is not active

Starter Signal

Indicates if the ECU is detecting the Engine Starter Signal is active. The NSS may block this reading so check that first!

– (ON) Starter Signal is active
– (OFF) Starter Signal is not active

NSS: Neutral Safety Switch Mode

Indicates if the ECU is detecting the Vehicle Shifter is in Park/ Neutral. This is used by Automatic Transmission ECUs to see if it is safe to start.

– (YES) NSS Signal is in Park or Neutral
– (OFF) NSS Signal is in a Drive gear

PROM: ECU Program Number

This is the ECUs reported Software Program Number and can give details on the type of program installed. These numbers are shown in Hexadecimal to save space.

– (B0) – Older Program Tune
– (B1) – Newer Program Tune

GPH/MPG = Current Gallons per Hour / Miles per Gallon

Displays current estimated fuel consumption in Gallons Per Hour. This is estimated from injector flow rate and injector duty cycle.

Note: This is only an estimate, as different injectors and other vehicle conditions will affect this. For accurate readings, the Fill-Up feature should be used for 2 consecutive Full Fill-ups so the REM can calculate actual flow rate.

On auto trans vehicles, MPH can be used to calculate Miles per Gallon.

AW-4 Auto Trans Readings

RPM = Transmission Output Shaft RPM

Displays the Revolutions per Minute of the transmission output shaft from the Vehicle Speed Sensor(VSS). May not read below 300 RPM.

MPH/KPH = Miles per Hour / Kilometers per Hour

Displays the speed of the vehicle. This is based off the transmissions speed sensor (VSS) and calculates speed from Trans RPM and other driveline options.

Note: Vehicle Driveline options must be set for accurate reading. This reading cannot account for transfercase 4-lo range.

0T = Transmission TPS Steps

Displays the Transmission side of the Throttle Position Sensor in Steps from 0 to 7. This is separate from the Engine side of the TPS but should still stay synchronized. This is used by the TCU to modify the shift points to intended driving style.

GEAR = Current Gear

Displays which gear the transmission is currently in. This only shows what gear the TCU has selected and may not accurately reflect custom bypass shifters.

PRND = Shifter Selection

Displays whether the Transmission Range Shifter is in a normal position (PRND) or a manual mode such as (3RD) or (1-2).

B12LC0T = Combination Trans Info Gauge

This is a combination gauge that displays most of the TCU gauges in one line. Readings will display on the screen when they are currently active.

– (B) = Brake Switch
– (1,2,L) = Solenoids
– (C/P) = Comfort/Power Switch
– (0T) = Trans TPS in steps.

 0/0 = TCU Error Codes

The AW-4 TCU has the ability to throw basic trouble codes. The first number is for Solenoid Codes and the second is for TPS Codes. Under the AW-4 TCU Menu, the right selection buttons will bring up TCU Error Screen and display current and stored codes.

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