Where can I pull power so the wideband will not reset every time I crank the car? - Miata Turbo Forum - Boost cars, acquire cats.

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Old 01-21-2010, 10:14 PM   #1
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Default Where can I pull power so the wideband will not reset every time I crank the car?

Right now im pulling power from the little blue plug under the hood on the drivers side.

Every time iIstart the car, the wideband resets, showing my AFR as 8 for a few seconds as it warms up when im trying to figure out the afr when cranking
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Old 01-21-2010, 10:18 PM   #2
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Get your volt meter out and start testing wires....but dont just tap wires off the ignition to power the wideband, you'd be asking for trouble. Have that lead control a relay with power coming from the battery.
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Old 01-21-2010, 10:21 PM   #3
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Quote:
Originally Posted by Dlaitini View Post
Right now im pulling power from the little blue plug under the hood on the drivers side.

Every time iIstart the car, the wideband resets, showing my AFR as 8 for a few seconds as it warms up when im trying to figure out the afr when cranking
Just turn the electrical on for a few seconds before you start the engine.
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Old 01-21-2010, 10:22 PM   #4
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The ecu, fuel, ign and starter circuits do NOT lose power during cranking.
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Old 01-21-2010, 10:27 PM   #5
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Quote:
Originally Posted by m2cupcar View Post
The ecu, fuel, ign and starter circuits do NOT lose power during cranking.
Don't use the starter circuit....then it'd only be on during cranking.....ecu or fuel is your best bet


I think I used the fuel pump lead to switch my relay....heres what it looks like...the blue 8ga wire is coming from the battery and then goes to one side of the distribution block (yes I know its not attached in this pic). The other side of the distribution block I used for my grounds. Just to give you an idea

DSC03258.jpg?t=1264127080
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Old 01-22-2010, 09:40 AM   #6
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Quote:
Originally Posted by Cspence View Post
Don't use the starter circuit....then it'd only be on during cranking...
Not so direct run to the +

but I should have said starting, as in leads from the ignition switch that provide power to those items that need to be on during cranking- like the igniter, coil... though I used the ecu lead for my wb also.
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Old 01-22-2010, 12:32 PM   #7
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Is it an LC-1?

In Logworks you can see text info on the guage as you crank such as 'warm up', [low voltage' etc. The LC-1 requires a min supply voltage of 9v. During cranking, especially if your cranking for excessive periods of time and are trying to dial in cranking PWs you will likely get the error code. Your voltage is probably dropping below the 9v min and the LC-1 throws a heater calibration error as it's trying to warm-up. Mine displays the 'low voltage' message just as the engine catches.

It happens with mine every so often and it's wired to the stock ECU 12v supply - LC-1 error code 4 IIRC.
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Old 01-22-2010, 12:42 PM   #8
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my LC-1 gets power from the blue connector too and has been working fine since
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Old 01-22-2010, 02:11 PM   #9
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Absolute best way to wire an LC-1 IMO:



Or, if you have a PNP, cut the stock harness and wire it in there (I've done this as well). The ECU gets a nice filtered 12v that is constant through cranking. Also, by wiring in all of the grounds at one point shared by the ECU, it does away with all of those nasty ground offset problems people complain of.
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Old 01-22-2010, 02:17 PM   #10
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I pulled my power right off the ECU power. And I grounded everything right on the chassis where the ecu mounts to the floorboard. Never failed me with the multiple iterations of my car.
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Old 01-22-2010, 03:56 PM   #11
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Just to let you know, the LC-1 will still "reset" because of the low voltage (E-9) and will require reheating again. Sure, not from 0% but it won't work if you plan to check your AFR during cranking.

Jim
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Old 01-22-2010, 06:10 PM   #12
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Quote:
Originally Posted by Reverant View Post
Just to let you know, the LC-1 will still "reset" because of the low voltage (E-9) and will require reheating again. Sure, not from 0% but it won't work if you plan to check your AFR during cranking.

Jim
I agree. I've never seen an LC-1 that doesn't flash for a few seconds after the engine has caught. Impossible to log AFRs during cranking unless you remote it via alternative power sources.
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Old 01-22-2010, 11:11 PM   #13
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This may be a silly question, but why would you want to try to measure AFR while cranking?

I mean its just going to be air and some unburned fuel coming out the exhaust which will probably read lean anyways.
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Old 01-24-2010, 02:56 PM   #14
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MAF power, or ECU power.
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Old 01-24-2010, 03:40 PM   #15
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Not from the ECU. If the LC-1 shorts, it will blow the ECU fuse and the car will stop dead on its tracks. Get power from the main fuse with an extra relay switched on by the ECU, with a 5A fuse.

Jim
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Old 04-10-2010, 12:28 AM   #16
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Sorry for the bump, but which color wire on the ecu harness is constant 12v?
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Old 04-10-2010, 05:42 AM   #17
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nevermind found it. blue/red
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