AFR Gauge And Stand Alone ECU

[Jotronic]

I'm not even sure how to craft the question for Google because I keep getting everyine except the answer I want so I'm asking the hive; How are an AFR gauge and a stand alone ECU run together so both can measure AFR? I guess what I'm asking is, is it necessary? I thought it would be so you don't have to crack open your laptop every time you want to see what your AFR is.

[Tom]

I'm not even sure how to craft the question for Google because I keep getting everyine except the answer I want so I'm asking the hive; How are an AFR gauge and a stand alone ECU run together so both can measure AFR? I guess what I'm asking is, is it necessary? I thought it would be so you don't have to crack open your laptop every time you want to see what your AFR is.

I'll take a swing, though it may not be any better than google. It really depends on the system and how it is set up. On one end of the spectrum, the wideband can be an entirely independent system you read via a gauge and/or its own logging system. You would use the AFR info supplied by the wideband to make your own changes to the tuning maps in the ECU. If the ECU has logging functions, you may be able to log the wideband output to produce one integrated log showing the AFR along with other sensor signals all sync'd up, so you know exactly what all the sensors (including wideband) were reading at each split-second of the log. Some systems can then recommend map changes based on logs like that, in an effort to achieve desired AFR's at various cells in the map. Many moderns systems go even further and offer some form of auto-tuning, where you select target AFR's and the system tries to adjust the maps as needed to get you there. Is that helpful?

[TC72]

There are a few was this can work, depending on if your ECU has an onboard driver for a wideband. If your ecu has a wideband wired directly into it, or if you have am external CAN based module with no gauge, then you need a laptop of a CAN based gauge/ display to see your AFR.

If you want to connect an external gauge like an Innovate or AEM to your standalone, they usually have a linear 0-5v output to provide the AFR from the gauge to the ECU. With this, obviously there is no need for another gauge. The downside is that the 5v output is subject to ground and power supply quality at the gauge, and can be less accurate than direct methods(sensor driver built into the ECU) or CAN drivers(signal transmission is digital, not analogue, so more liely to be accurate).

What the ECU can do with the information depends on the ECU. Basically all can enact a short term trim. You have an AFR target table, actual AFR, and the ecu can modify the injection quantity(within limits you impose). Some ECUs are better at this than others, or respond faster/ slower.

Some ECUs can enact a long term trim, where they see that a certain cell is consistently off target. They record, and gradually increase, a semi permanent change to that cell. Most ECUs that have a long term trim have a function that lets you write these changes in to the base table and zero out the trim table. This is handy for catching cells you couldn't quite get on the dyno, but shouldn't be used for "auto-tuning". Most auto tune features are slow, which is fine at low load but dangerous at high load.

TLDR; if your ECU has an onboard driver, use a CAN based gauge. This lets you see AFR or any other info from the ECU. If it uses an external driver (Haltech, MoTec, Link etc Lamda to CAN module), a CAN gauge is still the best way. If your ECU does not use CAN, run the output from a WB gauge to a voltage input on your ECU. The features in the ECU should work essentially the same, regardless of the source of the wideband signal.

[Bergerac]

My setup is;

CAN Wideband controller -> ECU -> CAN Gauge.

This way the wiring is simple, no need to mess around with multiple sensors/inputs, not prone to signal issues/interference and the CAN controllers are faster and have higher resolution. All the can wiring connects into a 5port hub along with my CAN EGT module.

The Canchecked gauge (MFD15) can display nearly any ECU value I want. I'm just about to setup a few buttons for boost and traction control as well.

Or you could be really fancy and replace your whole dash with an LCD screen like Bas.

[SirLapsalot]

How are an AFR gauge and a stand alone ECU run together so both can measure AFR? I guess what I'm asking is, is it necessary?

No, it is not necessary. Having a gauge in the car is just personal preference. Some like to see it for reference, some think it looks cool, some think it looks tacky.

If using closed loop fuel control then the ECU will require a wideband lambda input. Some have onboard lambda controllers (best case), some require external input from a CAN capable lambda controller like the Motec LTC or Link CAN-Lambda (next best case), or you can use an analogue input from something like an Innovate gauge (worst case/least reliable). You recently made a thread stating you've committed to a MaxxECU, which has onboard lambda control. So in your case the only reason to have a gauge is if you want to view AFR while driving for your reference. You'd just need to find any CAN capable gauge or dash display to put in the car. Keep in mind you can also just rely on internal logging from your ECU and view it later (far more useful...).