3000GT/Stealth AEM FAQ

Introduction to the AEM EMS

From the AEM Website:

"AEM’s Plug & Play Engine Management System (EMS) will forever change the way you look at and perform fuel injection tuning! This user-programmable system plugs directly into a vehicle’s factory ECU harness and requires no additional wiring or hardware. Windows™-based software (2000, NT, 98, 95, ME) makes the task of copying, viewing and manipulating data as simple as a click of the mouse. User-defined templates are easily configurable and enable tuners to establish “quick keys” to any pertinent information during the tuning process.The AEM EMS’s infinitely adjustable software allows tuners to program virtually any combination of engine control, power adders and auxiliary devices, and accurately deliver proper amounts of fuel and correct ignition timing for ANY boost level or operating condition."

Using an AEM EMS provides you with full control over the engine's running parameters. If you are patient enough to learn how to tune the system and understand the basics of engine control and tuning, you can extract more useful power out of your motor than is possible by using Piggyback devices and a stock Mitsubishi ECU. The AEM EMS will essentially allow you to do anything you want, within reason. Some special features are: vehicle speed-dependent boost control, nitrous oxide system control, traction control, 2-step revlimiters, drag-race antilag, user-definable knock control, closed-loop O2 sensor feedback at any running condition, and much more. You get complete control over fuel and timing, and full datalogging of every parameter in the system.

What do I need to run the AEM EMS in my car?

Since you are reading the 3000GT/Stealth FAQ, I assume you already have a 3000GT or Stealth. The Plug and Play version is configured to work with 3/S Turbo models between 1991 and 1997. You can just plug the AEM EMS unit in place of your stock ECU and successfully run the car using all the stock sensors, but higher levels of success have been achieved by adding a few other pieces: A wideband O2 sensor and controller is nearly mandatory to get your car running well with the AEM EMS. Without it, you will have to tune your fuel map solely by feel and trial and error. Using the Wideband, you can get an accurate reading of your Air/Fuel ratio at all times and do a much better job of tuning. The stock "Narrowband" oxygen sensors on your car are only calibrated to be accurate in a range near 14.7:1 A/F ratio, and will have a high level of variation between different sensors on different cars and should not be used to tune fuel ratios while under load. They are to be used only for tuning at light load and idle, for fuel economy purposes. By adding a Manifold Absolute Pressor sensor (MAP sensor) and Intake Air Temperature sensor (IAT sensor) you can change how the AEM EMS meters the airflow of your engine to a "speed-density" system and eliminate the restriction of your stock Mass-Airflow meter. The stock meter can be restrictive at higher flow levels, and a lower pressure drop between the atmosphere and your turbos' inlets will help turbo performance. Most AEM users will skip tuning the AEM with the MAF and go straight to speed-density for its higher performance potential. Exhaust Gas Temperature sensors (EGT sensor) can help you tune your car by indicating how well the charge in the cylinders is burning, and whether or not your timing is set properly. The only probes that are known to work with the AEM EMS at this time are supplied by AEM. They are an RTD-style probe, which works differently than the typical K-style thermocouple EGT probe you may be used to. The RTD probe is a bit larger, and uses resistance to indicate the temperature that the probe is exposed to. AEM says that the RTD probe reacts quicker than a K-type thermocouple, but regardless - they are the only type which will successfully interface with the 1311-model AEM EMS (3/S model).

How do I install the AEM EMS in my car?

Installation of the unit itself is quite easy. Remove the two trim panels on each side of the center console by where your feet go when sitting in the drivers and passenger seat. There is one screw on each side, hidden under a round plastic trim cover, and a pushpin style plastic retainer up by the footwell. Remove both, and the panels should pull out. The stock ECU is held in place by four 10mm bolts, two on each side of the ECU which is located behind the center console, under the radio area. On the driver's side of the ECU are four wiring harness connectors. To remove them from the ECU, there is a tab centrally located on each of the yellow plugs. Press the tab in, and the connector should slide out of the ECU with moderate force. Pull on the connector, NOT the wires. Remove your stock ECU. The AEM EMS will take the place of the stock ECU, with the wiring harness connectors plugging into it the same as they did on the stock ECU. If your car has "Active Exhaust", you will need to cut the wire going to pin #102 on the ECU harness in order to disable the Active Exhaust motor. If you do not do this, the AE motor will incessantly run and make a rather annoying noise. That's all that is required to get started if you aren't setting up a Speed-Density system. If you are installing a GM AIT Sensor, wire the sensor to pin 6 (black wire, ground) and pin 7 (red/blue stripe, signal) of the stock MAF connector.

If you are installing a 3-Bar GM MAP sensor, wire "A" should be connected to the Black TPS sensor wire (ground), wire "B" connects to the ECU EGR pin for your model year car (pin 53 or pin 73). Wire "C" should be teed into the Green/Yellow striped TPS sensor wire (+5V).

If you have purchased additional sensors - follow these links to installation guides for each sensor:

How do I set up a Basemap to start my car?

Open AEM Pro

File -> Open
Select 1311 MAF 91-93.V1.11.cal if your car is a 1991-1993 3/S
Select 1311 MAF 94-97.v1.11.cal if your car is a 1994-1997 3/S

REMEMBER - When entering values in cells, ALWAYS hit ENTER after each entry!

Setup -> Injectors -> Primaries -> Primary Inj Battery Offset Wizard
Select the type of fuel injector you are using if it is in the list, if your injector is not in the list, look on the AEM Forum for a battery offset table for your injectors. If none is there, you can send your injectors to AEM for free testing. Otherwise, select the stock Mitsubishi 3000GT/Stealth injectors for now.

If running a MAF setup:

Setup -> Sensors -> Mass Air Flow Sensor -> MAF Sensor Wizard
Select the type of MAF sensor you are using, if stock then choose Mitsubishi (DSM/3000GT/Stealth)

Setup -> Sensors -> Oxygen Sensor -> O2 Sensor #1 -> O2 Sensor #1 Wizard
Select your wideband controller for O2 sensor #1

Setup -> Sensors -> Oxygen Sensor -> O2 Sensor #1 -> Options - O2 Sensor #1
Set the O2 #1 gain initially to 0.96 - this will be tweaked later

Setup -> Sensors -> Oxygen Sensor -> O2 Sensor #2 -> O2 Sensor #2 Wizard
Select your wideband controller for O2 sensor #2 (if installed)
Repeat the gain setup for O2 sensor #2

Setup -> Sensors -> Air Intake Temp Sensor -> Air Temperature Wizard
Select the proper IAT sensor, Mitsubishi if using stock MAF, or GM/AEM if MAP.

Setup -> Sensors -> Coolant Temp Sensor -> Coolant Temp Wizard
Select "Mitsubishi (All)" unless using an aftermarket sensor.

Setup -> Sensors -> Cam/Crank Sensor -> Cam/Crank Sensor Wizard
Select "Mitsubishi 3000GT/Stealth (V1.11 Firmware and newer)"

Setup -> Sensors -> Vehicle Speed Sensor -> VSS Wizard
Select "Mitsubishi 3000GT/Stealth"

If you have an AEM EGT probe installed on your car:

Setup -> Sensors -> Exhaust Gas Temp Sensor -> EGT Sensor Wizard
Select "AEM (All Other EMS Applications)"

Your sensors are set up!

Setup -> Rev Limiters -> Main Rev Limiter -> Options - Main Rev Limit
Set Fuel Cut and Ignition Cut to whatever you want your primary revlimit to be, set ignition cut 100 rpm lower than fuel cut
Set Fuel Cut Load to whatever PSI boost you want a hard fuel cut to be at - overboost protection.

Setup -> Internal Logging
Set the conditions where you want the internal logger to log data
I use throttle at least 20%, rpm at least 2000

Set the parameters you want logged.

I use:

Fast 1: Engine Speed
Fast 2: Engine Load
Fast 3: Ign Timing
Fast 4: Knock #1 Volts
Fast 5: Vehicle Speed (for use with FWombat's Dyno Maths Library)
Fast 6: O2 #1
Slow 1: Air Temp
Slow 2: Coolant Temp
Slow 3: Knock #1 Fuel
Slow 4: Knock #1 Retard
Slow 5: Injector Duty
Slow 6: Throttle
Slow 7: O2 #1 FB Value
Slow 8: O2 #1 Target Error

Set the logging rate you desire - I use the fastest to provide the highest resolution.

Fuel -> Fuel Map -> Table
Right-click on the map and select "Change Injectors/Pressure"
Input 360cc/min at 45 psi for the stock injectors
Input your new injector size at 45 psi for your new injectors
Click "OK" to rescale the fuel map, crank fuel table, crank pulse table, and secondary options.

I recommend that you print out the resulting fuel map and ignition timing map before making the following change:

Setup -> Breakpoints -> RPM Breakpoints Table -> Table

You most likely will not be spinning your motor up to 10,500 RPM - so by squashing some of the breakpoints down you can increase the resolution in your fuel and timing maps.

I recommend the following for breakpoints:

500, 750, 1000, 1250, 1500, 1750, 2000, 2250, 2500, 3000, 3500, 4000, 4500, 5500, 6000, 6500, 7000, 7500, 8000, 8500

Note that making this change will not move around cells in your fuel map, so cells that used to mean 6000 RPM will now be in the cells for 4000 rpm. You will need to take the printout of the original fuel map and timing maps and input the proper values in the proper cells. If you are running MAP and made the flat fuel table, you only need to enter one row's worth and copy/paste the values to the rest of the table.

A similar problem will also plague your ignition timing map, so you will need to rescale it as well. However, the AEM basemap is so extremely safe for values that you can run it as-is after rescaling the RPM breakpoints. Trust me, you can safely run a LOT more timing than AEM specifies in the basemap.

MAP Sensor users only:

Setup -> Sensors -> Manifold Pressure Sensor -> MAP Sensor Wizard
Select the type of MAP sensor you are using, if you want to run speed-density

Fuel -> Advanced Fuel -> Fuel Trims -> Boost Fuel Correct Table
At the top of the map, note your highest load number. For each 14.5 psi (1 bar) you want to add 100% more fuel. If your top load is 29.48 psi, you want 203% more fuel in the highest cell.
At the bottom of the map, figure the same percentage of reduced fuel from 0 psi that you need. If your bottom cell is -13.10 psi load, then you want -90% in the lowest cell. (Enter negative numbers as 90-)
Select all the cells in the map, and right-click and select "Calculate". The map should fill in all the intermediate cells with proper values.

Fuel -> Advanced Fuel -> Fuel Trims -> Boost Fuel Correct Graph
Verify that your plot is a diagonal line, intersecting the X/Y axis at 0% and 0 psi. If it is not, check your calculations for the end load cells.

On your fuel map, select all the cells on the row closest to 0 psi. Hit Ctrl-C to copy them to the clipboard. Now select the entire map, and hit Ctrl-V to paste the values into the whole map.

This style map will look strange, as all columns now contain the same values (it is now essentially a Volumetric Efficiency map, and the Boost Fuel Correct map will add/remove fuel from the primary fuel map based on manifold pressure).

Tuning/Setting notes for v1.11 Software

Section under construction

Suggestions from 3000GT/Stealth Owners

Section under construction

How do I tune this thing?

Section under construction

Owner-provided Map Library

Section under construction