LC1 setup (ground offset)

[c5kid]

Ok, I have my LC1 wired up correctly. Thats not the case this time.

When I am key on, not running, my Logworks reads 22.3-22.1 when sitting. My Hptuners reads 21.09-21.0, using the LC1 pid already setup.

I tried using the (volt/.625)+10 and setting my LC1 to read 0v = 10 and 5v = 18, but that just made it worse, HP would say 17.36 while LogWorks still read 22.3.

How do i fix this? I have the offset excel sheet that a member posted up that allows you to plug your actual volts compared to commanded volts.

But I do not know how to command the volts on the LC1. Do you use the Logworks? If so where is it at?

[mr.prick]

You can't change the PID expression without changing the LC-1's output values,
that is what "made it worse".
You need to program the LC-1 with Logworks and then build your PID expression off that.
It should read 22.8% -22.9% in free air as well, re-calibrate it.

The HPT reading will never be exactly the same as what you see in LW
because it is analog signal and not serial.
Comparing analog AFR to serial AFR in my last log the difference was .17 average.

[LSxpwrdZ]

Not to mension the LC-1 has the noisiest analog outputs of any wideband I've personally ever used. I am running an LM-1 which is very similar to the LC-1 and here are my settings in both the LM-1 and my custom PID in VCM Scanner:

Wideband:
0v=10afr
5v=20afr
1/12 update speed

HPTuners PID:
1/0.5 + 9.8

My wideband does read off from time to time but it's usually only .1 and with the cells in the histogram averaging everything anyway will not cause any problems.

[c5kid]

I know the HP will never be exactly the same, but it shouldn't be off 1.2.

I did the free air calibration and see 22.8-23 when it is just hangin in the free air. When I stick it back into the exhaust (key on, not running) is when i see the 22.3-22.1 I am goin to free air calibrate it again tonight and see if I can get HP & Logworks to read alittle closer.

Thanks for the help guys.

[WS6FirebirdTA00]

If I had a dollar for every time this question was asked...

Try to search, there is a lot of info out there. You need to setup a custom PID and more than likely decrease the range on the WB for better resolution. It may not be exactly what the WB says, but you should easily be able to get it <0.1 error. Command a heater voltage in log works, record what HPT is reading, rinse and repeat. You may have to tweak the WB and HPT. I never use 0 or 5 V. I usually go from 0.3-4.7 V or so.

[c5kid]

WS6, where is the command heater voltage in log works?

[WS6FirebirdTA00]

LM programmer.

[c5kid]

Ok, i am sorry but your goin to have to step me through this. I know how to program the LC1. I have changed the slope before setting 0v=10, 5v=18

how do i command a flat line of 0.5v and go then 1v, 1.5v...etc up to 5v so i can see how many volts my HPtuners is seeing.

I am using LM programmer 3.25

[WS6FirebirdTA00]

Check the top, bottom and middle. It is in one of the tabs as the heater voltage.

[mr.prick]

You set the analog voltage slope to the same values. (flat line)
1v=10, 1v=18 or 5v=10, 5v=18 ect.
It can be programmed to emit a set voltage during warm up in the advanced section.

[WS6FirebirdTA00]

I just set my curve. If .3 volts is 11:1, I will command that voltage and monitor the scanner. I tweak the curve until it is dead nuts on the average. I do the same at the top end. The ends may may need to be tweaked so the 14.7 value is also correct. Once you get it, you will have rock solid WB to HPT logging. I see no difference from 11.0-17.0 in my WB.

[c5kid]

Thanks guys!!! I also recieved a suggestion from TXZ0603, I was grounding mine to the frame, cleaned the paint off a solid ground. He said try moving the ground to the negative battery term. Did this yesterday and did another free air calibration. Now the thing is .1 off.

Dialing it in from here should be pretty quick.

[pontisteve]

I know this is an old thread, but the problem here is ground offsets.

The HP Tuners logger is grounded thru the OBD2 port, therefore thru the PCM, and therefore thru wherever the PCM is grounded to.

The LM-1 is grounded thru the cigarette lighter, and ultimately its grounds.

The analog ground wire from the LM-1 should reference the PCM ground if possible, so everything is in sync with the same ground offset. So the LC-1 (or LM-1) should analog ground to PCM ground, and so should the HP tuners analog ground (pin 5) on the connector. This should make a zero ground offset. To be more clear, there should be an analog ground wire from the LM-1 analog ground to the PCM ground spot. There should also be a wire from the HP Tuners analog ground (pin 5) to that same PCM ground spot. Both wires could go to an eyelet that the PCM ground bolt goes thru.

If this is not done, the next best thing is to ground the analog ground to the engine block. Whether this is done or not, the next step is to measure ground offset. To do this, you get into LM Programmer, and command 2.5v = 10 afr, and 2.5v = 20 afr. The AFR numbers (or lambda numbers, if using them instead) do not matter at this point, since no matter what the AFR is, you're commanding 2.5v being output by the LM-1 or LC-1.

Now that we should have 2.5v coming out of the wideband no matter what, we can hook up the HP tuners stuff and log wideband voltage. Just enter in the formula Volts/1 + 0. That should give you raw analog voltage, which should now be 2.5 no matter what.

Whatever difference you find, is the ground offset. I did this yesterday on a Z28, and found that 2.5v output got me 2.58v input in the HP tuners software. (By the way, sometimes you can get less voltage, sometimes more voltage). I like to measure this with the car both running and off, to be sure I have consistent offset measurements here. If they're much bigger than .1v, look into wiring it like I described earlier.

Now, how important is this? Well, in my case at .08v, and assuming 0v will = 10 afr and 5v will = 20 afr, then each volt would be worth 2 AFR points. So .08v would work out to a .16 AFR error.

Now, lets calculate the formula correctly, shall we? First, take the range that the AFR has to spread. In our case of 0v=10 AFR and 5v=20 AFR, our range (or spread) is 10 AFR points. Now take the 5 volts and divide that by the 10 AFR point range we have to work with, and we get .5 Volts per AFR point. So our formula in HP tuners would be Volts / .5 + 10. (This last 10 in the formula represents the starting point of our AFR range, i.e. 10 - 20).

Lets try this again, with different numbers. Our AFR output formula in LM Programmer will be 0v = 7.35 AFR and 5v = 22.39 AFR. So our range would be 15.04 AFR. Divide the 15.04 AFR range by 5 volts and we get 3.008 AFR per volt. 5 volts divided by the 15.04 point range = .3324. [This is the inverse of 3.008!]. Our starting (minimum possible AFR) number will be 7.35 AFR, which means our formula will be Volts / .3324 + 7.35.

In other types of software, the inverse way of writing this formula is AFR = (Volts * 3.008) + 7.35. In HP Tuners, they make it more difficult by writing it as Volts / .3324 + 7.35. By the way, this 7.35 - 22.39 range was chosen because it's one of the default AFR settings used by Innovate.

Now, plug this into the EIO input as a custom user defined input. Take a look at the graph, and see if it comes out exactly right!

Note... if you use windows calculator, there is a button on there that says 1/x. This is an inverse function button. So if you punch in 3.008 and hit the 1/x button, it will result in a .3324 answer. Hit the button again, and the inverse will read 3.008 again. This 1/x button is also extremely handy to switch between lambda and equivalence ratio!

So, now that we know how to build a formula correctly, we still have to decide what to do about the ground offset. This isn't too easy in HP Tuners, since we can't modify volts directly. We can only modify the range the voltage has to cover, and the starting point of the range.

We either have to calculate what kind of AFR (or lambda, if using that) correction factor we need, and add or subtract that from the starting point box (the box on the right, in the custom input settings of the scanner), or we have to just remember to mentally add that correction in. If we go the mentally add route, then you add (or subtract, depending) the correction factor to the datalogged AFR.

In our above example, we put out 2.5 volts all the time, and the HP tuners software datalogged 2.58 volts (slightly bobbling around that number anyway) as the custom input, when we rigged the input to just spit out the voltage without any formula other than V/1+0. Since the voltage is higher, the AFR error we figured out (.16 AFR) will be added to the AFR number we datalog once everything is set up correctly. So if we datalog a 14.00 AFR, it's really 14.16.

If the ground offset turns out to read 2.42 volts instead of 2.50 volts, then we need to subtract that .08v offset (.16 AFR) from our readings. So if we set up everything right, and datalog a 14.00 AFR in this case, it's really 13.84. The important thing to remember here is that a lower logged voltage (2.42 vs 2.50) will make the wideband read richer than it really is! A higher voltage (2.58 vs 2.50) will make the wideband read leaner than it really is. Obviously, the 2.42 example is more dangerous if not compensated for!

And remember, since our voltage chart is adjustable, that means the ground offset can be a bigger or smaller difference, depending on the AFR range we use! And of course, the more ground offset voltage we have, the worse it is as well. The trick here is to get the formula right, ground the analog ground to the PCM ground, or the engine block (all by itself, not sharing ground with any other wires!!!), and then measure for and correct for the remaining ground offset that we're stuck with.

While it takes temporarily setting up LM Programmer to spit out 2.5 volts all the time, and then setting up HP tuners to log voltage/1+0 in a custom input PID to see what you are really getting (due to ground offsets) every time you set up for a car, it's worth it. Now you'll know you're correctly datalogging the real AFR or lambda reading. Now, watching the VCM scanner wideband AFR input, and watching your LC-1 or LM-1 in real time should match perfectly.

If your LM-1 or LC-1 has had a recent heater calibration and free air calibration, and if the Wideband O2 sensor is in truly free air, the oxygen content should display on the wideband gauge, which at least for me is 20.9. Your should be that or very darn close to it. If not, recalibrate the sensor in free air.