Forum Audi 80 Klub Polska

Hello, sorry i only speak english... I have one strange problem, so I am asking for help please.
I made a swap ABK engine in audi B2. Siemens ECU 43 pin
I connected everthing and started the engine, connected to VCDS and see that ECU voltage is dancing around. Reley 30 output was 7-8V, so I shorted relay, car was wotking about 2-3 sec realy good than engine stoped. There was no spark.
I changed relay 30, engine still don't start (don't have spark)and I have 17V on hall sensor. When I connect fan from computer to a hall sensor conector there is a spark.
How is posible the ECU feed hall sensor with 17V, when battery have 12.6V?

[ Dodano: 2020-01-04, 22:25 ]

BlackT pisze:Hello, sorry i only speak english... I have one strange problem, so I am asking for help please.
I made a swap ABK engine in audi B2. Siemens ECU 43 pin
I connected everthing and started the engine, connected to VCDS and see that ECU voltage is dancing around. Reley 30 output was 7-8V, so I shorted relay, car was wotking about 2-3 sec realy good than engine stoped. There was no spark.
I changed relay 30, engine still don't start (don't have spark)and I have 17V on hall sensor. When I connect fan from PC to a hall sensor conector there is a spark.
How is posible the ECU feed hall sensor with 17V, when battery have 12.6V?

It is not possible for you to have 17 volt on the sensor, you have a damaged ECU or you measure something wrong.

I measure voltage betwen 1 and 3 terminal on hall sensor. It is 17V, i checked serveral times. I don't know have ECU produce that voltage. On every other sensor volatge is similar to battery voltage

And what voltages do you have on the flowmeter and throttle potentiometer?


flowmeter - pin 4,2
potentiometer - pin 1,3


Maybe I measured the voltage between pin3 and the mass of the vehicle?

I will check tomorow and post here results

[ Dodano: 2020-01-05, 20:08 ]
On TPS and VAF I have straight 5V, between ECU ground and car ground there is no voltage.




Very very strange???

Check GND continuity. Measure the potential difference between the minus pole of the battery and the GND terminal in the Hall sensor plug.

I did that, no potential between GND of hall sensor and engine battery. It is really small, about 0.02V

Connect a 2 / 5W light bulb to the plug and check the voltage under load.

Despite the voltage, the hall sensor can easily withstand 20V ...

When I connect fan from PC voltage drop to about 10V...
I thout that hall can withstand that voltage but it looks like it can't . Output from hall is now always same as pin 1, when i rotate the distiributor it doesen't change to zero.

So i put zener 14V betwen pin 1 and 3, connect hall from other car, and when I rotate it with my hand I get spark.

The original hall must be able to withstand higher voltages than 14V if it were otherwise a larger half of the cars would have a failure when the battery was being charged or alternator failure.

So out of curiosity I will ask how there ground cable between 1 and 2 cylinder bolted? brown / red cable.

Even the cheapest hall sensor can hold 20 V, so i think Bosch can hold it without problems, but it looks like it can't. It is dead
I put distributor from ABT engine, engine start but it shows about 30% higer RPMs on VCDS, that beacuse ABT have smaller windows on metal sheet that triger hall sensor
Ground betwen 1 and 2 cil is tighten well and have good conductivity

BDW. now I have normal 12V on hall sensor

Interruption does not matter if it will be 40% PWM or 60% PWM, the motor controller will behave the same, the most important is the beginning of the pulse. Since the engine driver sees more RPM than it should mean that somewhere it does not connect hall pin2 - ECU either on GND power supply or + so I would look at power supply that would explain 17V

Do you have any vag? then you would give the group log 000

Strange i've never seen that voltage level in car:D
My first guess was that your broken hall sensors give back some additional 5v on supply but from the picture you measured voltage on disconnected hall.
And now you have 12V, interesting:)

Widocznie mało wiesz😜 niestyk jakiejś cewki czy elektroniki generuje napięcia wiadomo że są diody zabezpieczające ale napięcie może krążyć powstają szpilki z indukcji i miernik to wychwyci...

Nie od dziś wiemy że nie wolno spawac normalnie auta bo może uszkodzić elektronike takie spore napięcia mogą się wytworzyć.

dzięki Jarewa za info ale trochę o tym wiem ale kolega mierzył na wyłączonym silniku jak rozumiem