O2 Sensor Wiring With Powerfc/datalogit

[edizio]

I'd like to have a go at getting O2 closed loop feedback working with datalogit so I can get some stable fuel ratios off boost.

I don't have a fuel temperature sensor so on long journeys, it seems like I am getting some small fluctuations when temperatures change. That, I think, is the only explanation I have for my fuelling going slightly lean (0.5 AFR), on a long journey (150+ miles). I've checked air temperature, voltages, fuel pressure and all the corrections available to me to no avail. I've also raised before that I get a lean condition when turning air conditioning on which is annoying again; grounding all seems fine and voltage corrections seem fine. I've been investigating and found that from most tuners, you'll get these problems if you're running everything in open loop because there's just so many things that need correcting, i.e. a small rise in fuel temp changes the amount delivered.

I've got a regularly calibrated MTX-L wideband that I use for tuning which is plumbed into AN1-AN2 on datalogit. I've got O2 feedback turned off because I don't have any narrowband sensors on my car but I was thinking that I would be able to turn the MTX-L to provide output in lambda instead of AFR.

If I do this, where do I sort the wiring? is it basically wiring the wideband into the loom that goes into PowerFC? Datalogit just shows 0.005 for O2-1 and O2-2 constantly.

I would assume that once PFC sees the wideband putting out the voltages it expects for the O2 sensors, it shouldn't care whether it's a wideband or a narrowband and my AFR problems will go away. I can have the MTX-L display gadget just understand the voltages I tell it and to display the AFR accordingly so I shouldn't notice any visual changes.

Edited June 28, 2015 by edizio

[KiwiRS4T]

I don't know if the PFC has the capability to make the automatic corrections you are looking for.

If not you need one of these:

http://campaign.r20.constantcontact.com/render?ca=13724212-ccee-4b4a-9b30-b3988d06b7a7&c=0ff310d0-1d6f-11e3-b800-d4ae5275b546&ch=107f9960-1d6f-11e3-b805-d4ae5275b546

[edizio]

The link ecu is the eventual plan however I have got a few jobs to do first that are more serious.

Powerfc does have o2 sensor feedback but not as detailed as the link. Ie, only one target value as opposed to idle/off boost etc.

Basically this is a wiring question. Pfc corrections are working great for less than a 100 mile journey but heat soak, lack of fuel temp corrections due to no fuel temp sensor, etc is just sending me a tad lean off boost.

Edited June 29, 2015 by edizio

[GTSBoy]

All you need is for your wideband controller to have a narrowband simulation output. Whatever those two terminals are get connected to the narrowband input on the ECU. Job done.

If your wideband controller doesn't have a narrowband simulation output, then you are shit out of luck. There is no way to wire it up otherwise.

[iruvyouskyrine]

MTX-L does do narrowband simulation iirc

[MJTru]

Im not to sure, and from what i see you cant have the power fc self tune the fuel. I use a AEM wide band with a 5v output i use that, and hook it up to my data logger then log the AFR's remember to calibrate the channel.

Thats about the only way i know to do it. Log then work out the correction, then input it.

I'm not sure of what a a narrow band simulation is. Sorry will google it though

[KiwiRS4T]

Im not to sure, and from what i see you cant have the power fc self tune the fuel. I use a AEM wide band with a 5v output i use that, and hook it up to my data logger then log the AFR's remember to calibrate the channel.

Thats about the only way i know to do it. Log then work out the correction, then input it.

I'm not sure of what a a narrow band simulation is. Sorry will google it though

Narrow band simulation is a feature on some wideband meters that sends a signal via another wire to the ecu that replicates the signal it would have got from the stock Lambda sensor to regulate idle and cruise afrs - that's what the OP was after. Fully automatic regulation of the AFRS is only possible on some newer ecus such as the Link that I linked above.

[MJTru]

I understand thanks for that KiwiRS4T. So no more need for a oem stock 02 sensor. Cleaner looking engine bay. Now that you mensioned it i wounder if thats what the green wire is for on my wide band. I never pay no attention to it.

Link ecu looks good mate.

[edizio]

Hi guys,

Thanks for the posts! I've been out of town so haven't had access to my computer.

Simulating the narrowband from the MTX-L; I'll have a read up on it and see if I can wire it into the PFC, I think it's slot 29.

Regarding self tuning, that's not really what I'm after and when I get the Link ECU, I'll probably be using that but for now, I'm happy with the on boost fuel ratios, just a bit tired at having slightly rich or slightly lean AFRs on cruise and idle with the PFC as I have no O2 sensors.

Thanks!

[edizio]

Looking into it, you guys are right, the MTX-L does have a narrowband output. I believe the PFC is expecting 2x inputs so I assume I can just wire it up in parallel?