DIY PGMFI Diagnostics - Code 3 MAP

[ECU-MAN]

Disclaimer: The following is provided as a GUIDE ONLY, and neither myself nor Ozhonda take any responsibility for the outcomes of someone else doing the following. You follow these steps at your own risk!


No part of this DIY is to be reproduced with out acknowledgment of the site and author it came from, ie me and ozhonda.com. Do not rip parts off and claim them as your own.



MAP sensor "Manifold Absolute Pressure" also known as MP "Manifold Pressure" Sensor. MAP Sensor has two codes to it, Code 3 and Code 5. Code 3 is more of a disconnected or dead sensor. Code 5 is out of range or incorrect signal fault/function.

The MAP sensor is commonly located on the top of throttle body, however on pre OBDO and OBDO is located on the firewall next to the throttle body.




Aim:

Diagnose code 3.




Required:


Basic Testing

- Digital Multi Meter
- paper clip


Advanced Test

- Phillips head screw driver
- Digital Multi Meter
- paper clip
- vacuum pump
- vacuum gauge



Symptoms


For a faulty MAP sensor to trigger code 3, you will more than likely get the engine light come on and the car will go into limp mode, Limp mode is a preset fuel and ignition map running on a backup processor in the ECU. Limited to about 3500rpm and a rich mixture to protect the engine the engine will run but not the best. Common cause for code 3 is either a dead MAP or open circuit on the MAP sensor circuit to the ECU. Poor Installations of 3rd party piggy back systems can cause such problems.


Basic Test


- Perform a Visual inspection and make sure the MAP sensor is Connected


MAP Sensor Pin out Picture





**** Voltage Test ****



Set your multi meter to DC Volts ( 20v scale )

Step 1 ( Reference Voltage test )

Check the MAP sensor for its Reference Voltage from the ECU. Connect the Black Lead from your multi meter to the chassis for a good ground. Back probe* the MAP with the Red lead to Pin 1 of the MAP sensor while the sensor is connected.

KOEO* you must get 5v

If you get 5v proceed to step 2,




if you do not get 5v, repair open or short circuit to ECU from Pin 1 of MAP to the bellow ECU Pin ( also see continuity test below )

OBDO = C15
OBDI = C19
OBDIIa = D4
OBDIIb = C19

If you do not get 5v from the ECU pin above, replace the ECU.


STEP 2

Check MAP sensor for a good ground. Leave your Red lead from the above test on Pin 1 of the MAP. Back probe your Black lead into Pin 2 of the MAP.

KOEO* you must get 5v

If you get 5v proceed to step 3,


if you do not get 5v, repair open or short circuit to ECU from Pin 2 of MAP to the bellow ECU Pin ( also see continuity test below )

OBDO = C14
OBDI = C21
OBDIIa = D12
OBDIIb = C7


Leave your Black lead of the multi meter as is and move the Red Lead from Pin 1 of the MAP to the positive battery terminal. You should get 12v. If not, repair the wire between Pin 2 of the MAP and Pin listed above to the ECU



STEP 3


Check the MAP Signal. Connect the Black Lead from your multi meter to the chassis for a good ground. Back probe* the MAP with the Red lead to Pin 3 of the MAP sensor while the sensor is connected.


KOEO* at sea level you should get close to 2.9v
KOER* you should get close to 0.9v with a warm engine, 1.2v cold engine

as engine vacuum decreases MAP voltage increases





If you do not get a signal on Pin 3, replace the MAP sensor with a known good one and retest. If you do get a signal at Pin 3, then check the signal at the ECU end.

OBDO = C11
OBDI = C17
OBDIIa = D3
OBDIIb = C17


If you get a good signal at Pin 3 on the MAP and no signal on the above ECU Pin, repair the Open circuit between the above ECU Pin and Pin 3 of the MAP.

note: piggy back units like VAFC, Neo ect run in series with the MAP signal and could cause codes if your setup is sus.



***** Its is always best to check sensor inputs at the ECU side *****


**** Continuity Test ****


Set your multi meter to continuity. This setting is mostly a picture if a sound .))) when you touch the Red and Black leads together on your meter it should beep.


STEP 1

make sure the Ignition is off and unplug the ECU Connectors for this test

Continuity test between MAP Pin 1 and ECU, Connect your Red multi meter lead on the MAP Pin 1, Back probe* the Black multi meter lead on the ECU Pin below that suits your car.


OBDO = C15
OBDI = C19
OBDIIa = D4
OBDIIb = C19


your multi meter should beep and read short or 000.0ohms. Place the black multi meter lead on a good ground source. You should not get beeping, this is testing for short to ground.



STEP 2

make sure the Ignition is off and unplug the ECU Connectors for this test

Continuity test between MAP Pin 2 and ECU, Connect your Red multi meter lead on the MAP Pin 2, Back probe* the Black multi meter lead on the ECU Pin below that suits your car.


OBDO = C14
OBDI = C21
OBDIIa = D12
OBDIIb = C7


your multi meter should beep and read short or 000.0ohms. Place the black multi meter lead on a good ground source. You should not get beeping, this is testing for short to ground.



STEP 3

make sure the Ignition is off and unplug the ECU Connectors for this test

Continuity test between MAP Pin 3 and ECU, Connect your Red multi meter lead on the MAP Pin 3, Back probe* the Black multi meter lead on the ECU Pin below that suits your car.


OBDO = C11
OBDI = C17
OBDIIa = D3
OBDIIb = C17


your multi meter should beep and read short or 000.0ohms. Place the black multi meter lead on a good ground source. You should not get beeping, this is testing for short to ground.


If any of your continuity tests fail between the MAP and ECU, repair the OPEN in the wire between the MAP and ECU that failed.

If any of your continuity tests fail between the MAP and ground, Find the short circuit and repair it. look for squashed wires, or for damage to any part of the PGMFI loom.


reset the ECU and road test the car.


Advanced Test



With the key off, unscrew the MAP from the throttle body, undo the two Phillips head screws. Connect your vacuum pump to the MAP sensor's vacuum input.

Make sure the MAP is connected to the loom, Connect the Black Lead from your multi meter to the chassis for a good ground. Back probe* the MAP with the Red lead to Pin 3 of the MAP sensor while the sensor is connected.

Add vacuum to the MAP sensor, as vacuum increases voltage output from the MAP decreases and vice versa.

use the chart below to confirm correct operation,






replace the MAP if the output voltage jumps or glitches.



* Notes

KOEO = Key On Engine Off

KOER = Key On Engine Running

Back probe the sensor, use a paperclip and push it into the connector then touch/clip your multi meter lead to the paper clip


Disclaimer: The following is provided as a GUIDE ONLY, and neither myself nor Ozhonda take any responsibility for the outcomes of someone else doing the following. You follow these steps at your own risk!