TTransport

EE / layman help requested... I have a 2.2 Eurospec longblock in my 2001 with the factory ecu. The speed sensor that came with the long block is different than the one that was in my amu.
Symptoms: Intermittently the car won't start, I then throw my battery disconnect, wait 30 secs and then it starts. During daily driving I can't cross 3200rpms or the car throws up. It shuts down the throttle and changes the timing to 0. Then throws an implausible crank speed sensor. I already replaced the speed sensor but no difference.

I pulled the Bentley and ran the diags on my old speed sensor and it was fine, I had resistance between pins 2 and 3 per design and pin one is the ground. Then I got the Bentley equivalent for the 1.9TDI speed sensor that comes in the EuroSpec longblock. It says that pin 1 and 2 have resistance per design and pin 3 is the ground.

In reading the wiring diagrams I figured that I could mix and match to make it work, but I am concerned about the difference in resistance. What type / size resistor or capacitor would I install to get from 1100-1600 Ohms down to 730-1000 Ohms?

Below you will see my combinations and what works vs what doesn't.

Factory 225 amu wiring harness:
Pin 1 to pin 2 and pin 1 to pin 3 =2.5volts
Pin 1=Ground
Pin 2=ECU
Pin 3=ECU

225 factory amu speed sensor
Pin1=Sw=black =ground
Pin2=Br=Brown=ecu
Pin3=Ws=White =ecu
Pin 2 to pin 3 resistance 730-1000 Ohms

1.9TDI speed sensor
Pin1= Br=Brown=ecu
Pin2= Ws=White =ecu
Pin3= Sw=black =ground
Pin 1 to pin 2 resistance 1100-1600 Ohms(updated)

With the factory harness directly connected to the 1.9 Speed Sensor the car runs up to 3000 rpm and then I receive an implausible signal from the speed sensor and the car kills the throttle
= Pin1 SW-BR, Pin2 BR-WS, Pin3 WS-SW
Pin1=ground-ecu, Pin2=ecu-ecu, Pin3=ecu-ground

I then tried jumpers so Pin1,Pin2,Pin3 of the harness directly matched the pinout of the TDI harness and the car won't start
=Pin1 SW-SW, Pin2=BR-BR, Pin3=WS-WS

I then tried jumpers adjusting the jumpers so that the ground stayed in place and the ECU wires were crossed, the car started, but with the temp setup I can't drive to see if it breaks the 3000rpm limit. I'll pick up a connector tomorrow for a drive test and call Eurospec and find out what they have to say.
=Pin1 SW-SW, Pin2=BR-WS, Pin3 WS-BR

GorTT

on your OEM setup you are measuring resistance between pin 2 and 3 (ecu/ecu) but you say you are measuring the same two pins (2 & 3) on the TDI - but that's ground to ecu (why wouldn't you be measuring pin 1 to 2 on the TDI?). did you just typo, or are you not measuring ecu to ecu for some reason?

MCPaudiTT - DEFCON 1

will rescale it to 800 to 1050 ohms. You won't be able to match the 730 to 1100 without playing some games - the resistance would have to change as it scales. This can be done, but not with a simple resistor. I don't know how much current or voltage is going through the connection, so I can't recommend what wattage rating you need, but I imagine it is a pretty low current. I suspect if you use a 3k 1 watt resistor it would be fine. No idea if it would solve your actual problem, though...

3.5k will scale to 836 to 1100 ohms, and a 2.2k will scale to 730 to 930 ohms.

To calculate, use this formula:

Rnew = 1 / [ ( 1/R1) + (1/R2) ]

So:

Rnew-low = 1/[(1/1100)+(1/3000)] = 804
Rnew-high = 1/[1/1600+1/3000]=1043

TT_Nuge

Shouldn't your tuner have the answer/solution?

GorTT

:-)

MCPaudiTT - DEFCON 1

And as you likely know, it's no longer at the tuner...

M power this!

If you haven't already, post this in the 1.8T technical forum on Vortex

TT_Nuge

Exactly... seems like a fairly significant new territory issue and it's "no longer at the tuner"

TTransport

The OEM speed sensor has resistance between pin 2-3.
The TDI speed sensor has resistance between pin 1-2

with the correction you can see part of my dillema is the resistance, and part is the fact that the pin outs are differenct on the sensors.

GorTT

in other words you used the tdi pin/connector setup, then spliced the wires from the connector to the harness in the oem orientation, so it's either the resistance or a voltage difference, correct?