1999 VW Lupo ECU Change
Discussion
as before I appreciate everyones advice on this. I haven't yet sent the ECU off. The sensor that came out of the car that was working fine since my ownership was replaced with the same type the thinking being that it had always worked, so why change. For £3.95 its worth a go, so I will order and report back. My expectation is that it is one of two problems. The ECU not talking to the Port is not helping, but I have some time to check the wiring from one to the other this weekend, so lets see what I find !
I hope you have a wiring diagram
Disconnect the ECU before you start checking and going by the diagram disconnect anything else that is connected to the OBD/ECU loom, also pull all the fuses for the circuits you are checking, you need to be checking from A To B with nothing else possibly misleading you with false test results
Something else that catches people out is that although the wiring from A To B checks OK they forget to check for shorts to earth or live and also the possibility of a wire to wire short in the loom.
What I mean is although a wire continuity test shows up as good, the wire may still be at fault due to a short and a continuity test will not show up the short to neg, pos or another wire
Disconnect the ECU before you start checking and going by the diagram disconnect anything else that is connected to the OBD/ECU loom, also pull all the fuses for the circuits you are checking, you need to be checking from A To B with nothing else possibly misleading you with false test results
Something else that catches people out is that although the wiring from A To B checks OK they forget to check for shorts to earth or live and also the possibility of a wire to wire short in the loom.
What I mean is although a wire continuity test shows up as good, the wire may still be at fault due to a short and a continuity test will not show up the short to neg, pos or another wire
I don't yet have a diagram, the ECU is totally disconnected (its in the Kitchen !) I was hoping to be able to test the port in situ. please feel free to offer a 'how to' do it ! I was hoping that a simple bulb test would be sufficient, but I take on board what you say about breaks, earths shorts etc.
Have you cleaned the throttle body and reset the basic settings for throttle angle at idle yet?
After that I'd be looking for air leaks possibly use a smoke machine on the inlet manifold and see if any of the associated vac pipe work is split.
I think others have covered temp senders enough already, what diagnostic kit are you using? have you tried VAGCOM or generic OBD code readers?
After that I'd be looking for air leaks possibly use a smoke machine on the inlet manifold and see if any of the associated vac pipe work is split.
I think others have covered temp senders enough already, what diagnostic kit are you using? have you tried VAGCOM or generic OBD code readers?
benters said:
I don't yet have a diagram, the ECU is totally disconnected (its in the Kitchen !) I was hoping to be able to test the port in situ. please feel free to offer a 'how to' do it ! I was hoping that a simple bulb test would be sufficient, but I take on board what you say about breaks, earths shorts etc.
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I have a 1998 Lupo 1.4. The MIL (CEL/EML or whatever) light never came on, even for a bulb check. My initial thought is it had been doctored by a previous owner. There is a surface mount LED present in the speedo for it. I checked it was working. I then ran an instrument check with VAG-COM and it didn't illuminate the MIL (it did every other warning light and gauge) and showed no errors. My conclusion is that it was designed in by VW for future use but not activated in the ECU software until the relevant legislation came into force. Yours could be the same.
I had no problem reading codes with VAG_COM but another, generic, OBD reader wouldn't connect. I wouldn't be too hasty to blame the ECU.
I had no problem reading codes with VAG_COM but another, generic, OBD reader wouldn't connect. I wouldn't be too hasty to blame the ECU.
Edited by kabman on Sunday 17th January 20:15
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