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I'm at work already, the clock is 07.17 here in Finland
I'm running the RS4 MAF and don't unnecessary want to cut up the tapeing to do this as Dmitris pic of how to wire it up would be more helpful
1. Not used
2. Supply Voltage (12V)
3. Signal Ground (not directly connected to chassis ground)
4. Reference Voltage (5V with ignition on)
5. Measurement signal.
On the measurement signal you should have 2-3 volts when the MAF is unplugged and ignition is on.
Check that all the pins have correct voltages. I don't know how resistant the MAF is to short circuiting, because when using the proper connectors it is impossible to short circuit anything on it. So I don't know if it is protected or not from factory.
Worst case scenario you might need a new one (you can go for exchange unit and it is probably about 120 EUR), but check all the signals first and make sure they are correct.
The ECU is quite well protected in this regard, so I do not think you damaged anything inside the ECU... And I guess better run the wiring differently. It is not a good idea to run it right past the hot exhaust.
Basically I was suggesting a solution of a replacable section which could be made more heatproof. As the car is not stock its not going to matter. Once the best run has been determined, make two leads, keep one in the glovebox. Assuming that its possible to make a secure and waterproof/heatprrof connection at least as good as yours.
Basically I was suggesting a solution of a replacable section which could be made more heatproof. As the car is not stock its not going to matter. Once the best run has been determined, make two leads, keep one in the glovebox. Assuming that its possible to make a secure and waterproof/heatprrof connection at least as good as yours.
The part of the wiring that melted was not the wiring I extended.
It was the original wiring present in the car.
I do not see what that plugin section would accomplish at all when the wiring that melted was the one in the loom pre-maf connector.
The issue when adapting factory harnesses to other vehicles is that often you end up with wiring that is either too short or too long plus you have to make it fit which sometimes causes issues with brittle wires when you bend them against their set. Indeed that might explain the other issues you have as the even the youngest factory harness would be at least 16 years old!
Just an opportunity to remove that particular leg and replace it with something fit for purpose especially now as it has suffered damage. That could include rerouting away from the heat source and including more heatshielding to withstand the environment.
The issue when adapting factory harnesses to other vehicles is that often you end up with wiring that is either too short or too long plus you have to make it fit which sometimes causes issues with brittle wires when you bend them against their set. Indeed that might explain the other issues you have as the even the youngest factory harness would be at least 16 years old!
Just an opportunity to remove that particular leg and replace it with something fit for purpose especially now as it has suffered damage. That could include rerouting away from the heat source and including more heatshielding to withstand the environment.
I've started thinking about doing a new harness as there is alot of slack, quite a lot of left over connectors and then the neatness. Have to look into where to aquiring all sorts of connectors.
I did some measuring tonight on the harness, continuity is ok on every wire. Even measured resistance between wires to see if there were any shorts on them. The only two that showed up as shorted were 12V live on MAF and N75. I guess they are fed from the same source, but the ABY pinout site said nothing about any N75 12V live.
Ok the HFM5 pinout is as follows:
1. Not used
2. Supply Voltage (12V)
3. Signal Ground (not directly connected to chassis ground)
4. Reference Voltage (5V with ignition on)
5. Measurement signal.
1.
2. Were 12V, connected to pin 37 on the ECU
3. Were floating around 0.6 mV so I guess that's ok, connected to pin 26 on the ECU
4. Were 5V, connected to pin 25 on the ECU
5. Were 3V, connected to pin 7 on the ECU
... The only two that showed up as shorted were 12V live on MAF and N75. I guess they are fed from the same source, but the ABY pinout site said nothing about any N75 12V live...
The N75 and the MAF are *NOT* on the same fuse. The 3B/ABY N75 is on the S24 fuse and the MAF is on the S28 fuse. Both of these fuses are NOT activated *UNTIL* the ECU has energized the J17 Fuel Pump relay after it (the ECU) has received a G28 engine speed sensor signal that says the engine is turning over at more than 13 RPM (suggested by Paul N. - the manuals say 23 RPM).
HOWEVER, the MAF is fed through the Holding Relay inside the ECU with just the ignitions switch in the "ON" position.
3B but basically similar to ABY on this issue:
RS2'd 93 UrS4 5 spd sedan
94 UrS4 V8 6 spd manual avant
The issue when adapting factory harnesses to other vehicles is that often you end up with wiring that is either too short or too long plus you have to make it fit which sometimes causes issues with brittle wires when you bend them against their set. Indeed that might explain the other issues you have as the even the youngest factory harness would be at least 16 years old!
Just an opportunity to remove that particular leg and replace it with something fit for purpose especially now as it has suffered damage. That could include rerouting away from the heat source and including more heatshielding to withstand the environment.
There's absolutely nothing wrong with the factory wiring. Any wiring you are going to put against a 700C exhaust is going to melt. The factory wiring is very much "fit for purpose", the previous owner who swapped the engine in just did not take due care to route it properly.
Can't blame him either. It's all on me, tried routing it a bit differently and have it somewhat neat. But that didn't work out. You always learn from doing mistakes though.
I ordered a new MAF through a friend yesterday so I hope it'll run properly again soon. Atleast the S4 works nice
Yeah, if that doesn't sort I'll bring the proper isolation resistance meter from work and put 5,5 kV through the whole harness in the car and see how it likes it
Nah, but everything on the harness and ECU side of it looks ok.
Well today I got a new MAF, but to no luck. Still don't get any MAF signal.
I redid the continuity and short tests with my multimeter and everything is in its order. I measured shorts to every pin on the ECU connector and it's all fine. I had on pin number 2 in the MAF connector (12V) at first shorts to several pins. But after looking up what they were in the S2Central ABY Pinout site I came to it shorted through the electrical loads that were connected. I disconnected all the injectors and the ISV and then it showed no shorts.
I guess I'll have to sort a new ECU.
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