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Hacking up Honda's ECU
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PostPosted: Sun May 11, 2014 7:57 pm 
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Joined: Fri Jan 05, 2007 9:10 pm
Posts: 748
Hi there, I had an LC-1 wired to my ecu harness as such:
A25 Power
A26 Ground
D22 Sensor ground
D14 signal.

I get ZERO offset, no voltage fluctuation. Logworks always matches the D14 signal into Crome.

I purchased an MTX-L for permanent install into my car (removed the LC-1)
This gauge does NOT have a sensor ground, only power, ground and signal wires.

It's wired to
A25 Power
A26 ground
D14 signal.

Even with the engine off ignition on, the voltage fluctuates when ever the heater circuit turns the 02 heater on and off. The fluctuation is quite a bit and enough that I cannot log with this gauge. (the gauge display does not fluctuate however)

I have tried flat lining the AFR slope and it fluctuates quite a bit, so it's 100% a noise issue I believe from the heater circuit inside the gauge.
I have tried connecting directly to battery, fluctuation was the same and the overall offset was WORSE

QUESTION: Is there are way to hack this gauge internally and add a signal ground to D22 of my ECU harness. I believe this will separate the signal and power grounds and remove the voltage noise/fluctuation all together.


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PostPosted: Wed May 14, 2014 10:21 am 
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Joined: Sun Oct 17, 2010 10:56 pm
Posts: 27
Location: Texas
I would check to make sure all your grounds are good. Battery ground and all other grounds for ecu and anything else. Make sure you have good power connections and a good battery. I have had it when I had a weak battery and it made my temp gauge on my cluster show the engine was over heating. I haven't had a chance to look at your connections, I have a LC1 and have never had any issues. I also used the logging program that came with it and it worked fine. I will look this weekend to see if I can see anything you might be doing wrong.


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PostPosted: Sun May 18, 2014 8:12 pm 
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Joined: Fri Jan 05, 2007 9:10 pm
Posts: 748
As I was saying, I have had the LC-1 for years with NO issues.

It's the MTX-L gauge that does NOT have a signal ground. This is why there is ground noise.
Nothing to do with how the grounds are setup etc. You will notice ALL MTX-L users have noise of some sort that can't be reduced due to the design of the gauge combining heater ground with signal ground.

Just wondering if anyone has hacked it to reduce ALL noise from the MTX-L.

It's a design fault not an install error. I'm 100% on that. I have installed many widebands of different makes before, I do know how to install electronics correctly ;)

P.S Logging through direct serial won't show any ground noise as you are getting a digital signal direct from the device.
It's when you are logging through the 5v analogue signal you will potentially get ground offsets.


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PostPosted: Mon Jun 16, 2014 7:28 pm 
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Joined: Fri Jan 05, 2007 9:10 pm
Posts: 748
Anyone?
I'll open the unit up soon and check the board and components.

I guess this is a non issues with basically ALL tuning applications that can get direct digital data. HOWEVER: when logging onboard you are still only logging an analogue signal.
Therefore someone must have run into issues like this with the MTX-L.

I guess they buy a REAL wideband hehe (I just liked the gauge better than the 14 point 7 offerings)


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PostPosted: Mon Feb 29, 2016 1:30 am 
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Joined: Sat Feb 16, 2008 11:36 pm
Posts: 255
I have a gauge with cut harness that I'm gonna have to open up soon. ill take a look into it.

maybe it needs a capacitor or something to stabilize the voltage for when heater turns on and off.

I plugged mine into stock o2 sensor harness in the engine bay and it seems to be working ok
one time I managed to get it without fluctuation on a p30 ecu and then switched to another ecu and it was going crazy with same settings. I never was able to get it to stop fluctuating on a P72 ecu
Is it possible that p30 and p72 have a different circuitry for O2 input? and p30 might be more stable


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PostPosted: Mon Feb 29, 2016 1:48 am 
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Joined: Sat Sep 22, 2012 1:00 am
Posts: 204
Location: seattle washington, usa
tenshi_R wrote:
one time I managed to get it without fluctuation on a p30 ecu and then switched to another ecu and it was going crazy with same settings. I never was able to get it to stop fluctuating on a P72 ecu
Is it possible that p30 and p72 have a different circuitry for O2 input? and p30 might be more stable



The O2 measurement is an algorithm not a direct voltage read. The difference in the code is likely the difference in stability.


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PostPosted: Mon Feb 29, 2016 1:58 pm 
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Joined: Sat Feb 16, 2008 11:36 pm
Posts: 255
I wish I had that p30 still I would test for you.

maybe someone else has all I got is p72 ecus

I used these settings for p30
0v-10afr 3.67v-17afr and then adjusted the offset. and got it to stay solid maybe .3max fluctuation once in a while
changed ecu and right off the bat it was jumping around like crazy


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PostPosted: Mon Feb 29, 2016 11:14 pm 
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Joined: Sat Feb 16, 2008 11:36 pm
Posts: 255
not sure if that helps but heres some pics of mine
I really wanted to hammer the sht out of it since It just killed brand new 4.9 LSU sensor
but I took pictures before that

red, red/blk
blu, blu/blk
brown
yellow
black
black heat shrink
are in the sensor plug harness
the black heatshrink wire looks like a ground strap not a regular wire( one marked DRN)


Image

Image

Image


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PostPosted: Fri May 06, 2016 3:18 pm 
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Joined: Mon Mar 31, 2014 6:30 am
Posts: 20
is the A26 ground better than A23 ground to connect the LC1 ground ?


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PostPosted: Sat May 28, 2016 5:53 am 
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Joined: Sun Mar 08, 2009 11:12 pm
Posts: 101
Location: Malaysia
Hi Coupe-r,
May I know which wire that you connect to D14? Brown or yellow?
I did try connect yellow wire but afr reading fluctuate and do not same to gauge reading..

anyone got any advice...


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