How to check EA82 MPFI ECU codes

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Gannon
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How to check EA82 MPFI ECU codes

Post by Gannon » Wed Mar 19, 2008 6:51 pm

It comes up often enough, and everybody has a different idea of how to do it.

Taken from the 1988 MPFI XT Service manual. Applies to all MPFI EA82 engines with the 4 Plug ECU
Reading Codes from the 3 plug ECU's will be very similar

Function of Self Diagnosis
The self-diagnois function has four modes: U-check mode, Read Memory mode, D-check mode and Clear Memory.

There are 2 sets of connectors...
Black Single Spade Plugs
Green Dual Spade (T shape) Plugs
Both are located near the ECU, usually above the clutch area

And 2 lamps,
The Check Engine light on the dash (not avaliable in all areas) and the o2 Monitor LED (located on the side of the ECU)

U-Check Mode
Green and Black connectors disconnected with igntion on (engine not running)
In U-check mode, only the crucial MPFI components required for start up and drive are diagnosed. When a fault is found, the Check Engine light is illuminated to show there is a problem and the Code is displayed from the o2 Monitor LED.

Read Memory Mode
Black connected, greeen disconnected with ignition on
Used to display past problems that may be intermittent, like a loose connection or plug.

D-Check Mode
Green connected, Black disconnected with ignition on
Also known as 'Test Mode' and is used to check/adjust Ignition Timing and Idle Speed
Also used to check the entire MPFI system to detect faulty parts. Includes non-crucial items like EGR, Purge valves ect.

Clear Memory
Green and Black connected with engine running
Used to clear all current and stored codes. Clearing of memory should be perfromed after replacing a faulty part

How to read codes
The o2 monitor LED flashes the code corresponding to the faulty part
A long flash (1.2sec) indicated a 'Ten'
A short flash (0.2sec) indicates a 'One"

For example...

If the LED gives 3 long flashes and 1 short flash, it corresponds to a fault with the TPS

If there is more than one fault, codes will be given in order with a 1.8 second pause between codes

List of codes for 4 plug 1987.5 - 1994

11 - Crank Angle Sensor (no reference pulse)
12 - Starter Switch
13 - Crank Angle Sensor (no position pulse)
14 - Fuel Injectors 1 & 2
15 - Fuel Injectors 3 & 4
21 - Water Temp Sensor
22 - Knock Sensor (Turbo models only)
23 - Air Flow Meter
24 - Air Control Valve
31 - Throttle Position Sensor
32 - o2 Sensor
33 - Vehicle Speed Sensor
35 - Purge Soleniod
41 - Fuel Mixture Lean
42 - Idle Switch
44 - Wastegate Duty Solenoid (Turbo models only)
45 - Kick-down Relay (Auto models only)
51 - Neutral Switch (Manual models only)
55 - EGR Soleniod

List of Codes for 3 Plug 1984 - 1987.5

11 - Ignition System (no reference pulse)
12 - Starter Switch (remains OFF)
13 - Starter Switch (remains ON)
14 - Airflow Meter (circuit)
15 - Pressure Switch
21 - Airflow Meter (seized flap)
22 - Vacuum Switch
23 - Idle Switch
24 - WOT Switch
31 - Vehicle Speed Sensor
32 - Oxygen Sensor
33 - Coolant Sensor
34 - Air Temp Sensor
35 - EGR Soleniod
41 - Pressure Sensor (circuit)
42 - Fuel Injector
43 - Kickdown Relay

Note. When there are no codes to display, the o2 Monitor LED will flash a "Model Designation Code" Usually 1 for Turbo Manual, 3 for Turbo Auto and 7 for Non-Turbo
Current rides: 2016 Mitsubishi Triton GLS & 2004 Forester X
Ongoing Project/Toy: 1987 RX Turbo EA82T, Speeduino ECU, Coil-pack ignition, 440cc Injectors, KONI adjustale front struts, Hybrid L Series/ Liberty AWD 5sp
Past rides: 92 L series turbo converted wagon, 83 Leone GL Sedan, 2004 Liberty GT Sedan & 2001 Outback
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