Emerald, LC1 and 100 Ohm Resistors not playing ball!! - Resolved

[viperbl]

Ok, been trying to work out why my LC1 gauge is showing a different (less) reading to the emerald ECU, considering both are getting it from the same sensor.

 

So, I have the emerald set up to read in input aux 2 (pin 35) from 0-5v, AFR 11-16, I have also set this up on the LC1 with a sample rate of 1/3, all good.

 

Now, the LC1 will show 10.6 for example on start-up (pretty rich! but that’s another thing to sort, lol) and the Emerald will show 11.4 for example.

 

I put my voltmeter across the brown LC1 output wire, guess what, the voltage before the 100 Ohm?!!??! (1/4 watt) resistor was the same (converted to AFR) as the LC1 gauge, and after the resistor it was the same as the Emerald. So, the Emerald is not telling fibs, just showing what its been told ... seems the resistor is causing a voltage increase ...

 

Any ideas? I know nothing about resistors etc!!!!

 

Cheers, rich

 

 

 

 

Edited by - viperbl on 3 Jun 2008 08:52:13

[k80rum]

Not sure if this could be the problem or not Rich, but some of the Emerald inputs (AuxIn10 and AuxIn35) have pull-up resistors and Emerald say that if the LC-1 is connected to either of these inputs, the pull-up resistor should be disabled or "the analogue AFR signal will be distorted"

 

Might be worth a quick check because it's a quick fix if it is. It's on the "Inputs" page. The AFR/Lambda input is listed at the top. Assuming, this is showing AuxIn35, you'll need to make sure the AuxIn35 pullup resistor tick box on the RHS is unticked.

 

Hope this helps!

 

 

 

Darren E

 

K80RUM Website and Emerald maps library

 

Superlight R #54

 

 

 

Edited by - k80rum on 31 May 2008 01:09:21

[viperbl]

Thanks Darren, but I don't have the K3 upgrade yet, so still the old version.

 

Maybe its just me, but is the resistor not doing what its meant to do? drop the voltage?! Do I need this resistor in the older Emerald as well?

 

I also guess that resistors are not directional!?

 

 

[CageyH]

Resistors are not directional.

 

 

Only dead fish go with the flow....!

[Mike Scott]

Hi Rich,

Do you need to 100 ohm resistor in series 🤔 Unfortunately the manual I got with my Emerald doesn’t show the circuit for Lambda sensor, but with the 100 ohm resistor in series with the Emerald any current flow into or out of the Emerald will result in voltage drop from one end of the resistor to the other and hence different readings; as Darren says resistors aren’t directional. From what you say above it looks like the voltage difference across the resistor is about 0.5V which means the current flow through the resistor is about 5mA. This is quite a high current if both the Emerald and LC1 are supposed to be high impedance voltage sensing inputs

 

Give me a call if you want to have a chat.

Cheers

Mike

 

[Mr Locust]

Are you sure its not just the discrepancy from feeding a wideband LC-1 output into a narrow band input on the M3d controller i.e. the Emerald lookup table doesn't match the LC-1 characteristic.

 

Ian

 

Green and Silver Roadsport 😬 or Mrs Locust's Blue Roadsport Academy 😬

[viperbl]

All sorted.

 

Spoke to Emerald, they informed me that my older ECU may or may not have the pull up enabled on pin 35, it depends on the firmware that is on the ECU.

 

I tried it on pin 34 instead and its spot on now :)

 

He also informed me that there are different types of ECU water temp senders, they send different data out so the ECU might not recognise this. I think I may need to wait until I upgrade to the K3 to get this to work by calibrating it.

 

Thanks for your help guys.