Hello everyone, I have a1989 6 SPD. The SES light comes on and usually stays on. The car is running well. But, if I throttle it, the car bogs. I did some electrical testing and found out the purple wire to the MAF has no voltage. I have the FSM but I really do not understand the circuit pg 464, 6E3-A40. It looks to me like the purple wire always has voltage, fusible link. The orange wires that go to the MAF power and MAF burn relay have power. I should also note that the Fuel pump fuse does not have power. I am running the fuel pump off a fuse I piggy backed on. I’m thinking this is all related.

I ran TrunerPro RT I get a code 13 O2 sensor error. The MAF reads about 10/17 grams.

I would really like to fix it the correct way.

From the Diagram 6E3-A-40 the FP always has power at terminal A, correct?

Does ALDI terminal G have power always or only key on?

The MAF power relay terminal A always has power, orange wire correct?

The MAF burn off relay terminal A and D also always has power, orange and blue wires correct? What closes the MAF burn off relay switch, the car in run?

I’m looking at the diagram. It seems to me the oil pressure switch also always has power, correct?

Wire 994 the dark blue does it have 12 volts, I am thinking yes.

I want to apologize for this being so long. I’m trying to understand this circuit. I really want to fix it correctly.

Thank you for your understanding and help.

 

I can't answer all your questions, but I can answer the wiring ones.

PURPLE WIRE
The purple wire should have power when one of the following two cases occur:

1. The ECM or oil pressure switch closes. When the oil pressure switch closes it will energize the relay and switch the MAF Power relay to the "top" contact on the schematic (terminal A) and route power from the battery through the fuse link and the relay into the purple wire.

2. The MAF burn off relay is closed by the ECM. When the MAF burn off relay is closed power goes from the battery through the MAF Sensor Burn Off relay then through the "bottom" contact on the MAF power relay (terminal C) to the purple wire.

In either case 1 or case 2 the purple wire should have about 12 Volts to ground. If neither 1 or 2 apply it should be near 0 volts.

From the Diagram 6E3-A-40 the FP always has power at terminal A, correct?

Correct the fuel pump relay always has power at terminal A

Does ALDI terminal G have power always or only key on?
Two things have to happen for terminal G to have power. The oil pressure switch is closed (engine has oil pressure) AND the ECM has the fuel pump off (relay terminal D not powered by ECM). There will be no voltage at terminal G unless BOTH of these things happen.

I believe the intent of terminal G is to hot wire the fuel pump and make it run when the car is off.

The MAF power relay terminal A always has power, orange wire correct?
The MAF burn off relay terminal A and D also always has power, orange and blue wires correct?
both correct (as long as the fuse link is not blown.)

What closes the MAF burn off relay switch, the car in run?
The ECM will ground terminal F to turn on the MAF Burn off relay. I believe it normally does this after the car is turned off after running for some amount of time. If the engine is running with oil pressure this will not route power to the MAF (the MAF power relay will be switched to terminal A).

 

I ordered a new FP relay. I'm thinking these are the original relays. Thank you for the help