Wideband Accuracy: Facts & Issues

[jackedupcanyon]

Depends on what you mean by monitor. The data logger or the black box is needed for calibration of the sensor which is needed periodically based on usage. Depending on how you hook it up, you may also need a relay to only power the sensor when the vehicle is running.

[Rockrz]

Are there any plans by HP Tuners to build this capacity into their program so we don't have to buy additional equipment?

[EC_Tune]

No.

[Rockrz]

I'll bet they would look into it if some
of their competitors started doing this...

[Blades]

Building that functionality into HPT would be bad.. For starters, the 12V heater power would need to be hooked up to the hpt unit and then supplied to the sensor.. Portability would be very hard to implement. The integration means more 'stuff' can break.. There are many LC-1s that get 'bricked' and have to be RMA'd. With that kind of failure rate, are you sure you want that time-bomb integrated into the hpt unit?

Speaking of which, my LC-1 just died as the result of a firmware update (locks up on verification).. Can you believe that? And I went and bought another one... CAN YOU BELIEVE THAT? I should've read this thread. I don't want to swap widebands again, I did such a good job with this install too. I need a drink.

[ktoonsez]

I have only had LC-1's, does any system come with a cable that has a real length or do they all have a 2 inch cable coming off the sensor (Exaggerating).

[boomer]

Got my kit with the upgraded sensor yesterday

[proggod]

Got my kit with the upgraded sensor yesterday

Who did you get it from, and how much did you pay?

[boomer]

Who did you get it from, and how much did you pay?

got it from here. was like 378 shipped i think.
http://www.bmotorsports.com/shop/pro...roducts_id/582

[mgm1979]

don't suppose there's any way to pick up the AFX unit somewhere WITHOUT any sensor - I've got two brand spanking new Bosch sensors in my toolbox...and gotta replace this POS LC-1 unit ASAP.

[shanekennedy]

it sounds like the original poster is saying that because a company makes a fantastic upper-end product, their lower-end product must be better than the competition

sony has a wonderful picture on their 240hz 52" xbr7 lcd, but that doesn't mean their 19" tv's that sell @ walmart are better than the other 19 inchers

i've nothing for or against any of the manufacturers, i'm researching for my own purchase & just don't follow the logic in the original post

i'm curious as to why the details of the test were not posted & why the afx was not tested

[krunchss]

So is this what everyone is looking for? Sounds like they are now offering the AFX with the (upgraded) NTK sensor.

http://www.bmotorsports.com/shop/pro...roducts_id/582

Is this still a good price? (Noob here in the market for a WB)

Krunch

[jackedupcanyon]

They are the only ones offering this at this time. NGK said they would start packaging the NTK sensors with the AFX after there stock of bosch sensors are gone. Said in could be 8+ months before it is offered but would only be about $30 more.

[krunchss]

So quick math, Pay $365 now, or wait 8 months or more and see if you can save $75. Hmmmm.........

Option 2 - $260 for unit with LC1 sensor. Are they really that crappy?

Krunch

[krunchss]

Just curious,

Came across this one as well. Now, I have a gauge pod on my pillar with a worthless NB autometer A/F gauge in it. This would look cleaner in my application, and still be able to log the data to my tuner. Any comments on bang for the buck on this one?

http://www.egauges.com/vdo_ind.asp?T...mp&PN=ATM-3378

There is also a $50 rebate on the Autometer site right now if that makes it more worthwhile.

Krunch

[eficalibrator]

it sounds like the original poster is saying that because a company makes a fantastic upper-end product, their lower-end product must be better than the competition

Actually, yes. It has to do with the logic and construction of the controller (not the actual sensor so much). ECM makes the best wideband controllers on the planet and holds the patents for their particular logic for tip temp control, temp compensation, and other things that get carried across their entire line of wideband controls. From a engineering standpoint, this is a worthwhile reason for me to use their products over just about anything else.

I'd still drive "lower end" Chevy in a heartbeat over an "upper end" Chery or Ssangyong. Get it?

[ktoonsez]

For all you guys out there still following this post here is some data:

Had an LC-1 in my car for the last 4 months or so and used it to do my VE tuning and set the WOT area to 12.3-12.9 range.

Just went out and bought the AFX controller today and replaced the LC-1 with the AFX (my AFX had the same bosch sensor as the LC-1, didn't come with NTK sensor). Went out and did some logging and saw what post #1 was saying, the car was actually .2 to .6 richer than the LC-1 was reporting on the average. With the LC-1 I had several rows for the same column in the 12.8 to 12.9 range for WOT and the AFX ended up reading them as being 12.3 to 12.5.

So all in all, some good data here and suggests that the test was good at least for that AFR.

Now some other interesting side notes, I also watched my cruising area of the VE table to see the difference there and could not really see much of a difference between the 2 controllers, I would say the LC-1 came up richer again but only by .1 or .2 which would suggest it is NOT linear like Chris@HP was wondering about but progressively seperates on the richer side as you go richer.

Last thing to note is that one of my friends did the same thing about 3-4 weeks ago and showed the same data that I was seeing (car being .2 to .7 richer than the LC-1 was showing), so he went ahead and changed his tune to get the AFX say 12.9 thru the WOT area. Now here is kicker, he did this on a DYNO recording the Horsepower before and after and ended up gaining NO Horspower AT ALL once he got the AFX to read 12.9 in areas that supposidly "would" have been 12.2 because of the LC-1 reading higher that it really is. So his question about this whole thing is, if 12.9 is "usually" peak horsepower for an LS motor and supposidly the car was really running 12.2 then adjusting it to 12.9 according to the AFX, why didn't he gain any HP. So again his question was, was the car already at 12.9 and he really ended up making the car run 13.6 or so which would probably explain why he didn't gain any HP.

Comments, observations?

[BennyHHR]

I had questions as to the accuracy of my AFX when bought almost two years ago. Did a bunch of testing, including voltage issues, setting up average histos, without a confident solution. Even had exchanges with a NTK engineer on the issue.

First, realize that these and most others, compute lambda and convert that to a gasoline AFR value, even though you may be running an ethanol mix fuel. Stoic is usually considered to be 14.68, yet for some reason NTK considers it to be 14.57, so there's some of the difference.

After considerable testing with open loop tuning and seeing the resulting FTs when back in closed loop, looking at the histos for averages, etc., what I did was write a custom PID for the AFX. Their formula is: AFR = (V * 1.4) + 9. HPT's equivalent formula used in the supplied PIDs is: AFR = (V / 0.7143) + 9, which is the same. After doing considerable tests and some math, in the custom PID I used 9.33 instead of 9 for the adder in the formula.

From that point on, after open loop tuning was done switching back to closed loop always resulted on near 0 FTs, which tells me that the 0.33 "correction" resulted in accurate data. (The gage still reads a little low though.)

That seems to closely coincide with your testing, ktoonsez. You might want to try a modified custom PID for AFR and see what happens.

[eficalibrator]

Went out and did some logging and saw what post #1 was saying, the car was actually .2 to .6 richer than the LC-1 was reporting on the average...

This is par for the course in my experience. You're seeing the difference between a "bargain" wideband and one designed by a real engineering company. This is more evident at richer AFRs and higher temps.

Now some other interesting side notes, I also watched my cruising area of the VE table to see the difference there and could not really see much of a difference between the 2 controllers, I would say the LC-1 came up richer again but only by .1 or .2 which would suggest it is NOT linear like Chris@HP was wondering about but progressively seperates on the richer side as you go richer.

Getting the lambda=1.00 region right is relatively easy for a wideband since that's where pump current of the Nernst cell is zero. Being accurate outside of this region is what separates the toys from the tools.

So his question about this whole thing is, if 12.9 is "usually" peak horsepower for an LS motor and supposidly the car was really running 12.2 then adjusting it to 12.9 according to the AFX, why didn't he gain any HP. So again his question was, was the car already at 12.9 and he really ended up making the car run 13.6 or so which would probably explain why he didn't gain any HP.

There's actually a "plateau" near lambda=0.90 that makes pretty close to LBT (lean best torque). As long as a naturally aspirated engine is run somewhere relatively close to this, minor swings in AFR either way don't usually have a tremendous effect upon power output. I usually run on the rich side of this to get me more cooling and knock resistance so I can operate closer to MBT timing at WOT.

First, realize that these and most others, compute lambda and convert that to a gasoline AFR value, even though you may be running an ethanol mix fuel. Stoic is usually considered to be 14.68, yet for some reason NTK considers it to be 14.57, so there's some of the difference.

The stoich point for Indolene clear is 14.56:1, which is the the certification fuel used by OEMs for official emissions testing. Pure Iso-Octane (2-2-4 trimethyl pentane) has a stoich point of 14.68:1, which is why this number gets seen a lot. Keep in mind that the fuel you buy at the pumps is a cocktail of lots of different ingredients, each with its own stoich point and you'll be working against the average of all of these when tuning most street cars.

To avoid confusion, I work exclusively in units of Lambda so that I see an actual excess air ratio regardless of stoich point. All I have to do is make sure that the PCM's calibrate-able value fr stoich point is set properly for whatever fuel I'm using at the start and corrections based on Lambda make the tuning process incredibly simple.

[ktoonsez]

Here is a question for you guys that are using the AFX and I plan on calling them but are closed today I think. The max voltage I can get out of the yellow wire is 4.88V instead of the full 5 when the display is reading 16.00 AFR, has anyone else seen this? Suggestions?
I followed the recommendations and grounded the double black wire and the signal ground together at the battery and didn't extend the wires at all. My LC-1 had a little voltage drop, it always read 4.98 in air but 4.88 is a little too much of a drop and of course I had to adjust my formula to accomidate for the drop and did get the display and HP to match up, just want to know what is with the .12 V drop.