RCPro AFR reading differs from Innovate Motorsports DB gauge

[GTIspirit]

Anyone running an Innovate Motorsports LC1 with the DB gauge?
http://www.innovatemotorsports.com/products/db.php
I've noticed that the AFR logged by the RCPro was reading about 0.5AFR higher than what was shown on the DB gauge. Strange, because both are driven by the same analog output from the LC1, according to this transfer curve.

Excel graph of what I was reading from the RCPro. Was about 0.5AFR higher than the gauge. I fed the voltage into another analog input and acquired that as the raw voltage to double check the scaling. No issues with the math conversion between voltage and physical units. I also tried to use the virtual gauge to compare against my multimeter reading, but that wasn't a good comparison method.

Took another look at how I had the other analog output of the LC1 programmed to fake out the narrow band signal to the engine ECU.

Hmm, my readings should be bouncing between 0.85lambda and 0.912lambda, which is 12.5 and 13.4AFR. Which pretty much agrees with what the RCPro was telling me.

So I think it's actually the Innovate Motorsports DB Gauge which is incorrect, since it reads lower than it should. I calculated that about a 0.2V delta would account for the differing readings. Maybe the ground for the DB Gauge has a slightly higher resistance so the voltage is a little lower, causing the lower AFR?

Anyone else experience this when comparing their RCPro readings against their Innovate gauge?

[TrackRat]

I have had issues with Innovate reading a little low with their LC1 package. I did a somewhat similar test with actual measured vs Innovate vs AEM's and found the the actual and AEM read the same and Innovate a little low. Not sure that helps, but does confirm that Innovate does read low sometimes.

[brentp]

The definitive thing to do is measure the actual voltage at the RCP terminal block and map that back to the spec for the wideband sensor. The RCP raw measurement should be within 1% (due to the tolerance of components during mfg).

In the future a finer calibration could be performed in firmware.

[GTIspirit]

The definitive thing to do is measure the actual voltage at the RCP terminal block and map that back to the spec for the wideband sensor..

I did that, as best as I could. I jumpered the AFR input to another RCP channel and logged that channel as raw voltage. I then converted that voltage to AFR in Excel using the linearization formula. Exactly agreed with the physical reading logged by RCP.

Performing a plausibility check of physical readings to what the AFR should be toggling between, the RCP is correct (toggling between ~12.5 and 13.4AFR according to how my narrow band simulated signal is configured) and the Innovate gauge is incorrect.

I wanted to report the behavior because if like me you double check the RCP reading against the Innovate gauge, and note a discrepancy, you might question the product which is new to the market rather than the existing product. It appears the Innovate gauge really does read low..... Maybe it displays the min values during a time period or has some other funky logic.

So it's further reason to use the RCP virtual gauge.

[brentp]

\o/

We like to hear that!

[mark pietz]

I know I'm late to this party. I'm wanting to run an innovate a/f monitor on my dash, and my needs are really quite simple. I'm satisfied with the data log feature on my Megajolt Jr., except I would like to add the analog output from the LC1/LC2, which I read is 0-5V. So what all is involved - just cutting that trace at R6, and then plugging in the wire from the 02 sensor into the aux input?

How do this all work?

[brentp]

Hi Mark,

you've actually posted in a RaceCapture/Pro thread In any case, yes, what you read in the instructions would work.

[mark pietz]

Thanks for the confirmation. It looked like it was straightforward (too easy, actually), and it does look from the above posts that scaling should be a fairly simple exercise in interpolation. I see where innovate posts a table that equates that voltages within this range with commensurate a/f ratios. My problem will be when I add the turbo I'm using a sidedraft carb with a metering rod, and need to monitor a/f under boost conditions, needing to keep things within 12.0-13.0 under all boost conditions.

BTW, I have made a convert to the MJLT! Another IH "Scouter" has converted his 196 ci 4-cylinder and did a variation on my notching of a pulley sheave. In fact, I wish I had thought of it and I'll try to get him to post his install.

[brentp]

awesome!