Help wiring an LC-1 into AV input

[bigbloodyturbo]

Has anyone previously used the 0-5v output from an LC-1 controller to feed the syvecs a wideband signal? I have tried to do this and have used an AV input to do so. This is working however it reads approx 1volt lower than what the LC-1 is outputting. This results in the afr reading roughly 2 points richer than what my gauge says (and I trust the gauge). I think the problem is where I'm grounding things. I'm grounding the LC-1 heater to chassis and the 'system' ground to the same point, I was grounding the LC-1 analogue ground to chassis aswell but I tried ground this to the analogue ground on the syvecs and it is still reading wrong.

One thing I don't know is whether the LC-1 needs a pull up or if it supplied its own on its output. I have set up the LC-1 for a 0-5v output and I can see this when I meter it at the back of the input pin on the syvecs. Am I perhaps using the wrong input from the syvecs?

[pavlo]

What pin are you wiring it to on the syvecs? Are you sure the 0-5v output is configured correctly? There shouldn't be a problem. Are you using a serial fed gauge?

Ultimately it doesn't matter as you can adjust the syvecs linearisation to match what you believe to be the correct AFR.

[bigbloodyturbo]

I'm using pin 42 (off the top of my head), it's one of the AV inputs and is configured for 5v and I have used a linearisation I found on this board for the LC-1 which matched up perfectly with what my gauge tells me at various voltages. The gauge is fed from analogue output 1 from the LC-1 controller and the syvecs is fed from analogue output 2 which has been programmed to output 0-5v (1&2 are now identical).

The setup did work fine the first time I hooked it up, this was for about 20-30mins of tinkering but then when i restarted the car sometime later that evening the indicated voltage being seen was now consistently down approx 0.9-1volt. When I measure from the input pin to ground (with the LC-1 disconnected) I get the same approx 0.9volts. It's almost like the LC-1 is having to overcome this potential before it registers its own signal. Could this be dodgy ground offset?

[bigbloodyturbo]

I think we figured this out. Turns out the ECU was not grounded properly and everything was off. Vbat was off as was the map sensor. We grounded a power ground to the old ecu bracket and everything is reading normal, wherever the syvecs was grounded before (loom im presuming) had some sort of impedance.