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Old 02-24-2007, 02:37 AM   #1
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Default Jumpy LC1 Signal? Why!!!!

i installed my LC1 not too long ago with my megasquirt.
for some reason the signal is a bit jumpy, it goes up and down a bit.
is this common? i thought it was a unclean ground wire.
but i ran another wire from the battery to the signal gorund wire, it helped a bit but still kinda bad.

any suggestions?

thanks
simon
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Old 02-24-2007, 09:33 AM   #2
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At idle we are kinda jumpy sometimes
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Old 02-24-2007, 11:06 AM   #3
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a. Red 12V supply
b. Blue Heater Ground
c. White System Ground
d. Yellow Analog out 1
e. Brown Analog out 2
f. Green Analog Ground
g. Black Calibration wire

I've read numerous things that the LC1 will give you a jumpy reading if the Green Analog Ground and the White System Ground are not attached in the same spot. As in for a stable reading all your grounds need to share the same mounting point. I don't think the ground for the heater would matter though. That's the only info I've got for you.
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Old 02-24-2007, 01:02 PM   #4
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don't forget the resistor on the MS o2 input.
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Old 02-24-2007, 05:47 PM   #5
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resistor what resistor!!!
was i suppose to add something on the MS in order to get it to read the wideband?

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Old 02-24-2007, 06:34 PM   #6
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What do you mean by "jumpy"? Describe the behavior with a bit of detail.
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Old 02-24-2007, 06:39 PM   #7
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no, it will work fine, probably, but apparently many MS and LC1 users have experienced LC1 failure because the ms draws too much current through the o2 input. put a 330 or 470ohm resistor between the lc1 output and the ms input to prevent it.

your jumpy signal might be grounds, but it may also be correct. does it ever steady out? run it on the stoc ecu and see what it does at idle.
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Old 02-24-2007, 10:35 PM   #8
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From the Mega Manual
"Note: R11 and R10 form part of the EGO input circuit (with C10). It is very important that you do NOT install a capacitor across the sensor input before R11 (C10 comes after R10 and R11 and is fine). Some people have recommended adding such a capacitor to 'smooth' the sensor input. This will cause problems, especially with wide band analog outputs such as you find on Innovate's LC-1.

Also, if you have a wideband sensor/controller, be sure to ground the controller to the same point as MegaSquirt!"


I just happened to see that as I was assembling my unit tonight.
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Old 02-24-2007, 11:23 PM   #9
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Quote:
Originally Posted by Al Hounos View Post
no, it will work fine, probably, but apparently many MS and LC1 users have experienced LC1 failure because the ms draws too much current through the o2 input. put a 330 or 470ohm resistor between the lc1 output and the ms input to prevent it.

your jumpy signal might be grounds, but it may also be correct. does it ever steady out? run it on the stoc ecu and see what it does at idle.
no it doesn't even at a constant RPM and map, it still varies at least 1AFR. its kinda weird, i need to check the grounds again to make sure, if no good still i guess i'll try modifying the MS.

thanks again
simon
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