LC1 & DB gauge ground wire ... 16ga ok ? - Miata Turbo Forum - Boost cars, acquire cats.

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Old 11-19-2008, 12:31 AM   #1
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Question LC1 & DB gauge ground wire ... 16ga ok ?

I'm wiring up my LC1 and DB gauge.

Would it cause a problem if I ran a single 16ga wire from the engine as a ground? Then run that wire through the firewall & connected the LC1 & gauge's grounds to it?

This is how I have it setup right now...
But now I'm wondering if a single 16ga wire will be sufficient to ground everything.
I'm also using a 16ga ground wire from the gauge (I have 100ft of it so decided to use it) that I was going to connect to that single ground off the engine.

Or do I have to run each wire seperately to the engine ground point?
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Old 11-19-2008, 12:39 AM   #2
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You have to follow the directions EXACTLY as stated. No deviation whatsoever. I promise. You cut ANY corners, do anything your way instead of their way, and you will be yet another person who has hell with their finicky LC-1.

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Old 11-19-2008, 08:25 AM   #3
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Proof is in the pudding. Does it work?
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Old 11-19-2008, 08:49 AM   #4
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Proof is in the pudding. Does it work?
negative. LC-1's are wayyy too finicky. It might work fine for a month, then one day it will loose it's free air calibration. (super common problem from noise interfering with the controller).
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Old 11-19-2008, 09:52 AM   #5
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Originally Posted by SHOthang View Post
Or do I have to run each wire seperately to the engine ground point?
The LC-1 and the gauge should share a common ground wire. This is so that any potential difference in ground is common to both devices. That much is stated in the manual.

My engineers' intuition says that this ground should also be shared with the ECU. While this raises the possibility of ECU-centric noise (from the injectors, for instance) affecting the potential of the ground wire in question, it also ensures that the ECU and the LC-1 see the same ground potential, which eliminates the potential for inaccurate readings due to ground imbalance.

I'm in the process of installing mine right now. For power, I'm taking +12 straight from the battery through a 16ga wire and switching it through a relay connected to ACC (the radio's switched power feed, specifically.) I have the LC-1 and the XD-16 grounds are connected together and fed through another 16ga wire which I then crimped into one of the MS's own ground wires.

We'll see how it goes.
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Old 11-19-2008, 11:07 AM   #6
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Originally Posted by patsmx5 View Post
negative. LC-1's are wayyy too finicky. It might work fine for a month, then one day it will loose it's free air calibration. (super common problem from noise interfering with the controller).
I think the super common problem is user error.

I'm pretty sure I ran the main ground for the LC1 with the ground for the XD16 with the same 16 or 18 ga wire to the motor and have never had issue. Come to think of it, that was probably at least 2.5 years ago.
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Old 11-19-2008, 11:20 AM   #7
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Ben, you didn't have an LC-1 IIRC. You had some other Innovate setup, no?

My advise is follow the directions to the "T" and you won't have any problems. If saving an hour on the install is worth the frustration down the road of having to recalibrate and reprogram, have at it. Do a title search for "LC1" and you'll get pages of people having problems with their LC1's. No ****. Read through them, and you'll find 90% of the people that had problems with them resolved them by rewiring the LC1 per the instructions that were included with it instead of "their way".

My LC1 has worked fine for ~10 months. But it's wired up per the instructions.
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Old 11-19-2008, 11:27 AM   #8
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Ben, you didn't have an LC-1 IIRC.
News to me.

I have LC1 (2 now actually) and I also have an LM1 portable. In the past I also had the AEM UEGO which is not as nice as the innovate.
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Old 11-19-2008, 11:28 AM   #9
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Well, I must be thinking of someone else obviously. Ah yes, I was thinking of Joe Perez, my bad.
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Old 11-19-2008, 12:27 PM   #10
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I have all my LC-1 related grounds (heater, system, LED & switch from the calibration wire, and DB gauge) attached to one wire inside the car, and that wire runs through the firewall and is crimped & soldered to a lug that is on the same ground under the TB that the ECU uses. That single ground wire is 12 gauge, which is probably overkill, but it's what I had sitting around. My MS is a parallel install and I took the +12V for both the LC-1 and the DB gauge right off the boomslang. So much emphasis is placed on having the same ground point for the ECU & WBO2 that I figured I might as well use the same +12V also. I've had the LC-1 in for about 6 months, which includes a couple thousand street miles and a couple track days, with no issues whatsoever (knock on wood).
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Old 11-19-2008, 12:51 PM   #11
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Quote:
Originally Posted by ScottFW View Post
I have all my LC-1 related grounds (heater, system, LED & switch from the calibration wire, and DB gauge) attached to one wire inside the car, and that wire runs through the firewall and is crimped & soldered to a lug that is on the same ground under the TB that the ECU uses. That single ground wire is 12 gauge, which is probably overkill, but it's what I had sitting around. My MS is a parallel install and I took the +12V for both the LC-1 and the DB gauge right off the boomslang. So much emphasis is placed on having the same ground point for the ECU & WBO2 that I figured I might as well use the same +12V also. I've had the LC-1 in for about 6 months, which includes a couple thousand street miles and a couple track days, with no issues whatsoever (knock on wood).
I have mine wired like this except I have the 12v off the wipers. It read almost a full point richer in my logs than the dyno's tailpipe sniffer last week. Anyone know what the differential should be between the AFRs at the O2 sensor and the AFRs at the tailpipe after a cat? I'm going to try doing a little rewiring (I have a 6-wire version btw, not the newer 7 wire), but I've already ordered a AEM UEGO to replace it.
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Old 11-19-2008, 02:18 PM   #12
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Quote:
Originally Posted by ScottFW View Post
I have all my LC-1 related grounds (heater, system, LED & switch from the calibration wire, and DB gauge) attached to one wire inside the car, and that wire runs through the firewall and is crimped & soldered to a lug that is on the same ground under the TB that the ECU uses. That single ground wire is 12 gauge, which is probably overkill, but it's what I had sitting around.
That's pretty much exactly what I did, except mine's a 93 so it ground on the back of the engine and I'm using 16ga.

I'm using my +12v from an add-a-circut to the fuse box.

I was getting tired lastnight after wiring it up & I still have to wire up the analog out to my MSPNP so I haven't fired it up yet.

I will give it a shot on thursday and let you know how it goes.
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Old 11-19-2008, 02:29 PM   #13
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Quote:
Originally Posted by Joe Perez View Post
I have the LC-1 and the XD-16 grounds are connected together and fed through another 16ga wire which I then crimped into one of the MS's own ground wires.

Pretty much how I have mine. The Heater and System ground run through a 16ga wire into the center connector my boomslang. This run through another 16ga wire that splices into one of the MS grounds.
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Old 11-20-2008, 01:44 PM   #14
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Well, got the install done today and fired it up. To recap, power is direct from the battery, through a relay switched by the radio's power feed. Ground is to one of the MS's ground wires. LC-1 and XD-16 share common power and ground.

So far, so good. Even though the battery is being pulled to about 8.5v during cranking, the LC-1 seems quite happy. As a test, I should probably bypass the relay some day and see how it responds to actually seeing that sort of thing, but with the relay in place it's working fine for now.

I'm really impressed by how quickly the LC-1 responds compared to the AEM, and what's even better, my dash gauge and MegaTune finally agree! Near as I can tell, they are within 0.1 of each other in the range that I've been able to observe so far, which covers about 13:1 to 15:1.

Much happiness. Assuming it stays reliable, I'll be an LC-1 convert.
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Old 11-20-2008, 03:35 PM   #15
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So, I was in the garage getting drunk the other day and decided to use my superior art skills to draw up a rough sketch of how my LC-1 was going to be setup. I saw this picture today and busted up laughing. I figured you guys might get a kick out of it so I'm going to share with the rest of the class.

I posted it on a free hosting site so click on the thumbnail to view a larger image.




Here's how it looks so far in real life.





Haha.... Enjoy
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Old 11-20-2008, 06:54 PM   #16
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For some reason I like drawing stuff and coming up with plans when I'm drunk too.
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