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2014 Honda Civic - Wideband Dual EFIE troubleshooting!
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Parsons51 Offline

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Joined: Apr 2015
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Post: #1
2014 Honda Civic - Wideband Dual EFIE troubleshooting!
Good day all! New user here.. I am running into some issues with tuning my rear oxygen sensor. After several weeks of playing around with different adjustments I am still unable to get a stable setup. Here is what I have experienced thus far:

Vehicle: 2014 Honda Civic (w/ AF sensor upstream and oxygen sensor downstream)

I am running George Wiseman's Hyzor electrolyzer with the Wideband Dual EFIE.

First I would like to point out how sensitive my Honda seems to be with adjusting the pot on the upstream AF sensor. I followed the general recommendation of setting the pot at 1/4 - 1/2.. Too much.

1/4 turn will make my engine sputter hard.

1/2 turn will make the engine stop running almost immediately upon starting.

This isn't my main concern. My issue is with my downstream sensor. I cannot apply any voltage offset without getting the pending DTC, P0139 [Oxygen Sensor Circuit Slow Response (Bank1, Sensor2)]. Start my car the second time and the ECU throws a hard code.

I cannot adjust the downstream sensor without throwing that P0139 code. I have thrown other codes as well (P0136 being one I can remember off the top of my head).

After struggling with this for several days and pretty much doing all my adjustments by trial and error I decided to go over my checklist. I confirmed that I had the right wires coming off the sensors. I'm tapped into the blue wire on my AF sensor and the high-side voltage output wire on the downstream sensor (which is the black wire in this case).

There's an article on where Mr. Wiseman talks about newer vehicles using this check/procedure where the computer checks the integrity of the sensor by ensuring the voltage flip flops. Essentially if the computer doesn't see the output signal bounce back and forth it will cause trouble. I'm not entirely convinced this is the issue although "Oxygen Sensor Circuit Slow Response" has some correlation with Wiseman's description. I'm not entirely convinced because if you treat any fuel saver as a device that negates EFIE adjustment then by applying the correct offset using the EFIE shouldn't you end up back at the same reference point?

Currently I have my upstream sensor set at 1/8 turn (or clockwise to the first thin mark on the coarse pot. The downstream sensor has been a nightmare. I've tried setting it at the recommended .200mv, as well as everything in between. I even tried throwing maximum voltage offset on the downstream to see if the response would be different. So far nothing has worked.

On another note, I have an OBD-II reader that I observe live data from while driving. When I get the P0139 DTC go from pending status to hard code the reader spits back "Closed loop, fault" and the Short Term Fuel Trim for sensor 2 (downstream) goes to 99% as if I were in open loop mode and coasting down a grade with foot off the accelerator.

Where do you recommend I go from here? I am a bit concerned that where I am dealing with a new vehicle that the solution may not be well understood.. or maybe it's something to do with Honda? Any input will be greatly appreciated. In the meantime I will continue the battle!
05-27-2015 03:59 PM
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lu4cor2 Offline

Posts: 1
Joined: Apr 2016
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Post: #2
RE: 2014 Honda Civic - Wideband Dual EFIE troubleshooting!
Hey there Parsons!Wink How are you? I'm sorry to hear that you are having so many troubles getting your efie to respond correctly. I tell you what, I have definately been there multiple different times. I can tell you almost for a fact that any vehicle from about the year 2005+ will need to have all of the other circuits addressed as well! I would start with lowering your lean-out limits. Meaning you would need to apply resistance to your iat, and ect circuits to gain more operating room for tuning for the ecu. Every ecu, or pcm has limits, that it won't go past, but by adjusting these two sensors first, I am certain you will have a lot easier time getting the gains you want. Also address either your maf/map sensor to lock in your gains for good. ALso are you 100% sure that you have the correct wires for your signal wires on your o2 sensors. This is the biggest and first mistake that most users come across. Also make sure you have the wires hooked up on correct spot on your efie. If you have any more questions or comments..i'm more than happy to help.
04-25-2016 05:05 PM
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