Stupid check, but need to verify WB 5v input is correct

[itsdaveonline]

I have the BM AFR500 / NGK AFX. What's odd is that HP scanner reads about .5 AFR units leaner than numbers on the built in wideband display. I consider the wideband display the source of truth as the WB sensor is processed on the same hardware with the screen.

During power the power on / ignition on sequence this wide band performs 3 known output voltages that represent the stoich, lower, and upper values. Generally speaking these values display around 14.68AFR, 9.11AFR, 15.97 AFR so thats good...

BUT sometimes I notice the power up sequence shows as 14.86AFR, 9.27 AFR, 15.97 AFR. Min max voltages are around
.20v min 4.97 max. Is there anything I can do with my formula to better adjust for voltage offset? I'm using the mfg. recommended formula and datalogging via A/C pressure sensor. 9+[PID.7101]*1.400.

What else can I plug into the formula to account for offset!? thnx!

PS analog ground and wideband ground both connected to same point, and have tripple checked grounds are good, WB is also calibrated.

[ecotec88fiero]

I have the BM AFR500 / NGK AFX. What's odd is that HP scanner reads about .5 AFR units leaner than numbers on the built in wideband display. I consider the wideband display the source of truth as the WB sensor is processed on the same hardware with the screen.

During power the power on / ignition on sequence this wide band performs 3 known output voltages that represent the stoich, lower, and upper values. Generally speaking these values display around 14.68AFR, 9.11AFR, 15.97 AFR so thats good...

BUT sometimes I notice the power up sequence shows as 14.86AFR, 9.27 AFR, 15.97 AFR. Min max voltages are around
.20v min 4.97 max. Is there anything I can do with my formula to better adjust for voltage offset? I'm using the mfg. recommended formula and datalogging via A/C pressure sensor. 9+[PID.7101]*1.400.

What else can I plug into the formula to account for offset!? thnx!

PS analog ground and wideband ground both connected to same point, and have tripple checked grounds are good, WB is also calibrated.

Where is it grounded?

[itsdaveonline]

Right beside the where the battery grounds. My finger is pointing to where the battery - terminates. The little black wire with the blue collar is 5v analog ground and the larger black wire is wideband power ground.

ground.jpg

[ecotec88fiero]

From that picture and what you are describing, you need to find a better ground. Painted sheet metal is never a good ground.

Terminate it at the battery termination point on the body. Usually the factory CTS grounds are electroplated and work great.

[itsdaveonline]

For what it's worth the factory ground where I'm pointing terminates on what appears to be the sheet metal. I also sanded off the paint and brought it to bare metal where those 2 wires ground.

[ecotec88fiero]

Alright I just couldn't tell from the picture how well it was prepared. Factory termination point have two or three threads of electroplated metal that is formed into the sheet metal so usually its a better spot is all.

You could adjust the voltage offset then but every AFX unit I have used hasn't needed it.

Have you contacted Ballenger?

[itsdaveonline]

Nope not yet, was planning to contact them but says they are on holiday hours.

I could try moving the two grounds to where it terminates on the battery neg or where the battery neg grounds to the chassis, just not sure how to do that since these wires are so tiny and fragile, also the eyelet connectors are way small.

Im open to whatever suggestions though. How do you adjust the original formula to account for voltage offset? Can you spell it out in plain English for me? I'm not much of a math geek so something close to a copy and paste solution or a clear formula would be much appreciated.

[MikeOD]

Reading different than the display is normall...the display on that wideband is calibrated to display 14.57 at Lambda 1.0...the voltage in at stoich is probably correct when you see 14.68 during the power up sequence, it just means you're calculating AFR assuming that's lambda 1.0.

If you work in Lambda instead, you can just ignore the display...but you still do seem to have an intermittent issue since it shows different when powering up sometimes.

[itsdaveonline]

Reading different than the display is normall...the display on that wideband is calibrated to display 14.57 at Lambda 1.0...the voltage in at stoich is probably correct when you see 14.68 during the power up sequence, it just means you're calculating AFR assuming that's lambda 1.0.

If you work in Lambda instead, you can just ignore the display...but you still do seem to have an intermittent issue since it shows different when powering up sometimes.

I have no issues being .10 AFR off reading. Don't care to use lambda either right now. But .50 AFR discrepancy is too much.

Agreed on intermittent problem. My max voltage is always at 4.97v during powerup. But min voltage and lambda / stoich values are sometimes too high. How do i correct in hp tuners or physically speaking.

[ecotec88fiero]

The problem that you run into is if you modify your offset to make them agree during one condition, the other condition will be off.

You usually add your offset to the the offset value in your wide band formula. If using AFR, the AFX has a +9 offset so your offset would be +9.5 or +8.5 depending on which way your AFR is offset.

It is odd that when your AFX unit does it checks only two of the three values are offset.

I would try changing your ground and doing a voltage drop test on your power and ground wires of the AFX unit during start up to verify there is no problem with your wiring.

If no problems are found, shoot an email to Ballenger, they have always been helpful with any of my questions.

[DSteck]

You need a more solid ground. Period.

[itsdaveonline]

Okay with that said, it seems your confident that's the issue. I guess i either connect to battery negative terminal or where the battery negative negative cable grounds to the chassis.

[Crawler]

If you are getting different readings on various startups. Then it is in the wiring or the controller itself. Those startup readings are a verification tool.

If they were always the same 3 numbers but were off from Ballengers set numbers, then it could be in the formula. However with them changing between startups, that tells us that its in the wiring or the controller. (Odds are wiring)

The guys above are correct.