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-   -   LC-1 Narrowband settings for OBDII (https://www.miataturbo.net/general-miata-chat-9/lc-1-narrowband-settings-obdii-11057/)

arga 07-06-2007 12:56 AM

LC-1 Narrowband settings for OBDII
 
I'm getting CELs with the factory NB defaults on analog 1. Does anyone have a 99/00 and an LC-1? Even if you have another OBDII year, if you don't get CELs let me know what you're running.

I just set the delay to 1/6 of a second. The A/F gauge seemed to be moving a little slow vs the stock NB when it was set at 1/3 of a second. I'll try that tomorrow and see how that goes.

Thanks

Joe Perez 07-06-2007 09:24 AM

Assuming you haven't checked the codes, I'd bet the CEL you're getting is for O2 sensor heater failure, not O2 sensor signal.

The ECU monitors the amount of current being consumed on the wire that powers the heater in the stock NB sensor. As you have presumably removed that sensor, the current is now zero, indicating a fault condition.

The quick and dirty fix is to re-attach the stock sensor to the harness and tie it up out of the way. Careful not to touch anything important- it does get hot.

Edit: I just noticed your signature says MSII. (?)

arga 07-06-2007 10:37 AM

I didn'think about the heater. I knew the LC-1 had a heater circuit too and just assumed they would draw the same power.

I normally run MSII but I had a smog check last weekend so I pulled everything out. The LC-1 went back in first and I noticed the CEL come on. I had seen the CEL before but assumed it was my MS tune. I may need to get a code reader and remove some of the guessing.

Joe Perez 07-06-2007 11:41 AM


Originally Posted by arga (Post 129191)
I didn'think about the heater. I knew the LC-1 had a heater circuit too and just assumed they would draw the same power.

Apples and orangutans.

The LC-1 sensor heater (red wire) is powered by whatever line you have it hooked up to, and grounded (blue wire) straight to ground.

By contrast, the heater circuits in the stock O2 sensors, though supplied by a regular switched +12 feed (black / white off the "engine" fuse), are grounded through individual lines that go into the ECU and are current-sensed. On a 2000, the front O2 heater return is a Violet / Yellow wire on pin 1U of the ECU, and the rear sensor heater return is a Red / Yellow wire on pin 3V.

The ECU monitors the current flow through these lines in order to verify that the heaters are operating. If it detects that the current flow is too high (indicating a shorted heater) or too low (indicating an open circuit) it will throw a CEL.

I guess if you wanted to be brave you could wire the LC-1 heater ground to the ECU heater ground return and hope that the sensor heaters are similar in their current draw characteristics.


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