i installed an lc-1 along with the aeroforce scan gauge and am having issues figuring out what slope and interept to use. i also need to figure out what to program the output of the lc-1. i tried to use slope = 1 and intercept = 9 but that is obviously wrong as i am not getting any useful #'s out of it. if someone could tell me what BOTH the scan gauge and the lc-1 should be set at, i would love you forever.
i thought i calibrated it. i left the sensor unplugged and turned power on to the lc-1 for 20 seconds, turned off power to it for 20 seconds, plugged the sensor to the wideband and turned power on for 2 minutes. i thought that it was calibrating when i did that. maybe not? has anyone else not used the optional button?
ok i went back through the directions for the lc-1 and found that the default analog 2 output is 0v=7.35 and 5v=22.35. so using that i calculated the slope to be 3 and the intercept to be 7.35 (put 7.3 in since it is only accurate to the tenth). took it out and all i saw was either a 7.3x or a 22.3x, nothing in between. why would the lc-1 only put out 0v OR 5v?
Did you calibrate you lc-1 ?? if not you could have weird reading
i have the lc-1 xd-1 and at first i could not see anything, i had to program the lc-1 and xd-1 and do a calibration
i just read that i should wait 6-8 hours after turning the car off before calibrating the sensor since it is still in the exhaust. i did not wait that long before i calibrated it when i first installed it. i am guessing this is my problem.
ok i went back through the directions for the lc-1 and found that the default analog 2 output is 0v=7.35 and 5v=22.35. so using that i calculated the slope to be 3 and the intercept to be 7.35 (put 7.3 in since it is only accurate to the tenth). took it out and all i saw was either a 7.3x or a 22.3x, nothing in between. why would the lc-1 only put out 0v OR 5v?
are you sure you have analogue 2?, i'm not sure but analogue 1 is more 0 to 5 Volt (maybe 1 V) it's far in my head
check the calibration again and make sure your ground a connected rignt
a good way to make sure evevry thing seem ok...at idle or driving normal you should have an afr of 14.7
What are you using for the ground location for the LC-1? I would use G102 [see diagram below (it is located between "LEFT PARK/TURN SIGNAL LAMP" and "POWERTRAIN CONTROL MODULE" towards the front of the engine bay)] because the Aeroforce Interceptor uses the same ground. According to Innovate Motorsports, you want to use the same ground as the data-logging device (yours being the Aeroforce Interceptor). I would then ground the "heater" wire next to G102 (but NOT on the same bolt as the LC-1 main ground).
to be honest right now all the grounds are hooked up with one eyelet to a screw inside the fuse box. i didn't know where the scan gauge would ground, so i just put it to a ground close by.
What are you using for the ground location for the LC-1? I would use G102 [see diagram below (it is located between "LEFT PARK/TURN SIGNAL LAMP" and "POWERTRAIN CONTROL MODULE" towards the front of the engine bay)] because the Aeroforce Interceptor uses the same ground. According to Innovate Motorsports, you want to use the same ground as the data-logging device (yours being the Aeroforce Interceptor). I would then ground the "heater" wire next to G102 (but NOT on the same bolt as the LC-1 main ground).
Let me know if this works for you.
my ground is not going to reach that far. i would have to add 3-4 feet of extra wire to it if i was to ground it there. would it be ok to do that?
ok i went back through the directions for the lc-1 and found that the default analog 2 output is 0v=7.35 and 5v=22.35. so using that i calculated the slope to be 3 and the intercept to be 7.35 (put 7.3 in since it is only accurate to the tenth). took it out and all i saw was either a 7.3x or a 22.3x, nothing in between. why would the lc-1 only put out 0v OR 5v?
are you sure you have analogue 2?, i'm not sure but analogue 1 is more 0 to 5 Volt (maybe 1 V) it's far in my head
check the calibration again and make sure your ground a connected rignt
a good way to make sure evevry thing seem ok...at idle or driving normal you should have an afr of 14.7
analog out 1 is 0v-1v and it is hooked up to an autometer a/f gauge. right now all it does is sit on full rich all the time. i double checked it and the autometer gauge is hooked up to the yellow lc-1 wire and the scan gauge is hooked up to the brown lc-1 wire. i know the calibration has to be off or else the autometer gauge would not sit on full rich.
My ground is not going to reach that far. i would have to add 3-4 feet of extra wire to it if i was to ground it there. would it be ok to do that?
I would bet that the way you have it grounded is what is causing all of the problems. I found this information on the Innovate Motorsports forum (The BLUE text is all about the importance of grounding and the RED text is the ideal placement for grounding):
A lot of people have problems understanding correct grounding and how it effects AFR to voltage conversion of the analog outs of an LC-1.
Lets first look at the basics of what is going on there electrically:
Think of Voltage as the pressure in a line (measured in Volts, symbol V).
Different to pressure though, there is no “absolute” Voltage. Voltage can only be measured as “pressure” difference between 2 points.
Current is the amount of flow of electrons, like gallons per minute in a water line. Current is measured in Amperes or amps (symbol I).
When water flows through a line, there’s a pressure loss along the line because the of the friction of water against the pipe walls and other restriction. Same goes for electrical current. Everything that conducts electricity has a resistance to that current flow and therefore causes a Voltage (pressure) loss along that conductor. The resistance is measured in Ohms (symbol R).
The Voltage (pressure loss) along a conductor follows Ohms law:
V = R * I (Voltage loss is resistance times current).
Different to a home plumbing system, the electrical current runs closed loop. What goes out of the + side must come back on the ground (-) side.
This “return” current is what creates ground offsets.
When the engine is running, the alternator acts as “pump” for the electrons. The battery is then just an electrical power consumer, like everything else. The “head” side of the alternator is its B+ terminal. The “suction” side of the alternator is the body of the alternator itself, that usually has good contact with the engine block.
All the current for all electrical systems in the car has to flow through the ground strap of the engine. If for example the total electrical current load of the car is 10A, these 10A have to flow through the frame and then through the ground strap back to the alternator/engine block.
If there is electrical resistance in that path, as there always is, a voltage loss is created along that path. For example if the path resistance is 0.1 Ohms, at 10A a voltage loss of 1 Volt is created. This means that the frame sits at +1V when measured against the engine block (remember, voltages can only be measured as difference between 2 points).
Now assume the ECU is grounded to the engine block, but your LC-1s system/analog out ground is grounded to the frame. The LC-1 measures its output voltage referenced to its “ground”, as that is the only zero reference it has. The ECU measures its O2 input voltage against a different zero reference, namely the engine block. As the LC-1’s zero reference sits 1V higher than the ECU reference, the ECU will read 2V on it’s input. Of course, you could compensate by programming the LC-1, but that is not a very good solution because:
a) The LC-1 cannot output what it regards as “negative” voltages. It references everything to its ground, and therefore 0V is at low as it can go. 0 Volt would even then be read as 1V by the ECU/datalogger/display.
b) The 1V ground offset as described in the above example depends on the current in the return path. With a 0.1 Ohm resistance in the return path and 10A electrical current you will have 1V. With 20A current you would have 2V. With 2A electrical current you would have an offset of only 0.2V.
c) The current load in a car, and therefore in the return path, can change very dramatically from 2-3 Amps to 50-100 Amps in milliseconds due to ignition systems, fans, a/c clutch and so on. These changing currents will create corresponding changing ground offsets which then is often wrongly attributed to "noisy analog outs". This "noise" can often be seen when displays intended for NBO2 sensors are used. On LED instruments, multiple LEDs will light up at the same time.
A better way is to ground the LC-1 to the same reference point where the receiver of the data, wether its ECU, datalogger or display instrument is grounded. This way all devices are “on the same page” and ground differentials somewhere else have no effect.
This is also the reason the LC-1 has different grounds for heater (large current) and system/analog out ground. The potential ground offsets created by the heater current when they are connected together can create its own problems. By connecting the heater ground to the same grounding metal as the rest you will minimize that effect. Therefore the best way is to ground the LC-1’s heater to the same area as the other grounds, but on a seperate bolt/lug. The contact points of bolts and lugs can account for 75-80% of the resistance of the connection and can change dramatically when corrosion sets in.
I have extended wires before and have had good luck. What I would do is get some wire (similar in size to the wires your extending) and attach them with solder. Once attached, use heat sink to cover the wire/solder attachment. Personally, I wouldn't use crimp connectors.
Keep me posted on how everything turns out.
Last edited by Turboholic™ : 06-16-2006 at 10:03 AM.
everything is soldered and heat shrink wrapped now, except for the grounds. i will try a free-air calibration first to see if that helps. if it does not i will move the ground. thanks for your help!
i did a free-air calibration and it works like a charm. i did not have to move the ground, so i lucked out there. it reads 14.5-14.9 at idle, so i figure it is getting a pretty good reading. thanks for the help guys!
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slope and intercept settings for lc-1?
Linear Mode
