PLX Stopped communicating

K-Series Programmable ECU installation questions / support issues
94vt3c
Posts: 17
Joined: Fri Feb 07, 2020 12:08 pm

PLX Stopped communicating

Post by 94vt3c »

I have a 94 Civic Coupe with a K20A2 with KPRO4 and PLX wideband that suddenly stopped communicating with the KPRO. Everything has been working fine for about 6 months. I went to start the car after sitting for a few days, voltage was low on the batt so it struggled to start. Started up and plx said NO SENSOR DETECTED. Went through all the troubleshooting I could. Checked wiring, changed sensor, checked input settings, reloaded a previous known good calibration and nothing. Disconnected the PLX from the Digital input on the KPRO and the PLX works fine without it. I am stumped as to what is wrong here. Called tech support was advised maybe a low voltage issue. Ran the car, 14.7 output from the alternator, battery holding 12.8 volts. Any help would be greatly appreciated. Any other info needed please fell free to ask.

Kpro Serial 49396
version 4.4.2.0
Ecu Model #37820-PRB-A05
Ecu Serial#2068-508455 0D19
Purchased direct from Hondata
Attachments
PLX disconnected from KPRO
PLX disconnected from KPRO
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20200207_135731.jpg
20200207_135731.jpg (2.16 MiB) Viewed 377 times
20200207_130801.jpg
20200207_130801.jpg (2.81 MiB) Viewed 377 times
20200207_134714.jpg
20200207_134714.jpg (1.96 MiB) Viewed 377 times
PLXFAIL.kal
(165.6 KiB) Downloaded 10 times
1994 CIVIC EG COUPE(EJ1)
K20A2 Boosted E85
Kpro4 PLX Wideband

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Spunkster
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Re: PLX Stopped communicating

Post by Spunkster »

Have you contacted PLX Devices about this issue yet. Since it seems to be related to how the gauge is reading it may be an issue with the wideband controller itself.

94vt3c
Posts: 17
Joined: Fri Feb 07, 2020 12:08 pm

Re: PLX Stopped communicating

Post by 94vt3c »

I will reach out to PLX however I believe it to be an issue with the KPRO.
1994 CIVIC EG COUPE(EJ1)
K20A2 Boosted E85
Kpro4 PLX Wideband

94vt3c
Posts: 17
Joined: Fri Feb 07, 2020 12:08 pm

Re: PLX Stopped communicating

Post by 94vt3c »

Waiting for PLX devices to look over the test data of their controller and get back to me. From what I see it seems to function properly. Here's the test instructions they sent as well as the results.

Instructions:
Ok. There are some tests we can do. 
First have the SM-AFR get power direct off battery. Then see if you get some better behavior. Also try adjusting your ground being used. This is not permanent solution, but a good place to start to see if anything is noticed right away, as well as when going through other testings. 

Next, You will need a DMM multimeter to check voltage, a cigarette lighter, and to remove the O2 sensor from the install location in the pipe. Please carefully and thoroughly follow the steps below exactly as we have written them.


1. With the O2 sensor disconnected from the SM-AFR, power on your set-up and see what your readings are on the DM-6 and what the voltage is on the bottom right pin of the analog port on the SM-AFR.

Then,

2. With the O2 sensor removed from the pipe and exposed to free air, reconnect the O2 sensor to the SM-AFR and see what your readings are on the DM-6 and what the voltage is on the bottom right pin of the analog port on the SM-AFR.

Then,

3. With a cigarette lighter, expose the fumes of the lighter fluid by pressing on the gas, expose the fumes to the tip of the O2 sensor for no more than a couple of seconds. This will create a RICH condition. When you do this see what your readings are on the DM-6 and what the voltage is on the bottom right pin of the analog port on the SM-AFR.

4. After you do the third step your readings should go back to what was shown on the second step.

Let us know what you get for each of the 4 steps with your voltage output and the AFR readings on the gauge. Respond back with the below break down but fill in the readings in the blanks.
1. DM-6 AFR:______ Voltage output: _____
2. DM-6 AFR:______ Voltage output: _____
3. DM-6 AFR:______ Voltage output: _____
4. DM-6 AFR:______ Voltage output: _____

Additionally, you can do the same 4 steps, but with your SM-AFR get power directly off of battery. This will bypass any potential power or current issues that may occur. The O2 sensor heater element is powered by the SM-AFR, so it pulls quite a bit of current. If there is a current issue it could cause the AFR readings to lag, freeze, or be inaccurate.

Results:

Direct power and ground to the PLX


1. DM-6 AFR:_14.5_ Voltage output: _2.286_
2. DM-6 AFR:_AIR_ Voltage output: _5.148_
3. DM-6 AFR:_10.0_ Voltage output: _0.100_
4. DM-6 AFR:_AIR_ Voltage output: _5.148_
1994 CIVIC EG COUPE(EJ1)
K20A2 Boosted E85
Kpro4 PLX Wideband

fonzeka
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Joined: Thu Feb 11, 2016 4:15 am
Location: Sweden

Re: PLX Stopped communicating

Post by fonzeka »

The gauge and the kpro board is reading the same serial data from the sm-afr module.
If the gauge works by it's own and stops working when the kpro is connected it seems like it could be some wiring problem.
Unless it's the kpro board itself that is the problem but that seems a bit strange?

94vt3c
Posts: 17
Joined: Fri Feb 07, 2020 12:08 pm

Re: PLX Stopped communicating

Post by 94vt3c »

The only thing I can think of is it's the KPro board. Like I said the wideband reads fine on it's own. All wiring is the same and w as s working for over 6 months. The car runs fine. Kpro can still make adjustments to fuel maps parameters etc. I think something is wrong with the digital input. Any ideas on testing the board to see if there's a malfunction?
1994 CIVIC EG COUPE(EJ1)
K20A2 Boosted E85
Kpro4 PLX Wideband

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Re: PLX Stopped communicating

Post by Spunkster »

Try using an analog input instead of digital and see if that works.

94vt3c
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Re: PLX Stopped communicating

Post by 94vt3c »

Connected to analog. Changed parameters to configure analog. Analog is reading signal but not nearly as good as the digital used to before this issue.
1994 CIVIC EG COUPE(EJ1)
K20A2 Boosted E85
Kpro4 PLX Wideband

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Re: PLX Stopped communicating

Post by Spunkster »

It sounds like you may have a wiring issue with the digital wiring.

94vt3c
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Joined: Fri Feb 07, 2020 12:08 pm

Re: PLX Stopped communicating

Post by 94vt3c »

I forgot to say the analog input is reading signal but not displaying A/F . When hooked up digital the Digital 0 read a flat 10.0 as well as the A/F. With Analog connected A/F sits at 14.70. Does nothing with throttle change. Analog 0 reads around 13.90 at idle and has changes with throttle.
1994 CIVIC EG COUPE(EJ1)
K20A2 Boosted E85
Kpro4 PLX Wideband

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Re: PLX Stopped communicating

Post by Spunkster »

This sounds like an issue with the PLX wideband controller. It seems as though the signal is too weak and it causes the controller to go into some error mode.

94vt3c
Posts: 17
Joined: Fri Feb 07, 2020 12:08 pm

Re: PLX Stopped communicating

Post by 94vt3c »

Just ordered a new plx complete. Will update after install
1994 CIVIC EG COUPE(EJ1)
K20A2 Boosted E85
Kpro4 PLX Wideband

94vt3c
Posts: 17
Joined: Fri Feb 07, 2020 12:08 pm

Re: PLX Stopped communicating

Post by 94vt3c »

Update: Brand new PLX installed. Analog working Digital still not working to KPRO.... No Sensor Detected
1994 CIVIC EG COUPE(EJ1)
K20A2 Boosted E85
Kpro4 PLX Wideband

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Re: PLX Stopped communicating

Post by Spunkster »

Post pictures of exactly how this is connected to the K-Pro and any wire connections for the wideband.

94vt3c
Posts: 17
Joined: Fri Feb 07, 2020 12:08 pm

Re: PLX Stopped communicating

Post by 94vt3c »

Please forgive the shotty wiring, this is only temporary until I find the problem. Last photo is the placement of the old PLX.
Attachments
All connected digital and analog
All connected digital and analog
20200217_203940.jpg (2.32 MiB) Viewed 294 times
Digital input and ground
Digital input and ground
20200217_204011.jpg (2.55 MiB) Viewed 294 times
Power and ground. 5 amp fuse inline
Power and ground. 5 amp fuse inline
20200217_204059.jpg (2.66 MiB) Viewed 294 times
Only reads this when set to digital and digital ref is connected
Only reads this when set to digital and digital ref is connected
20200217_204255.jpg (1.8 MiB) Viewed 294 times
Custom 3d printed cover with PLX mount
Custom 3d printed cover with PLX mount
20200217_204506.jpg (2.68 MiB) Viewed 294 times
1994 CIVIC EG COUPE(EJ1)
K20A2 Boosted E85
Kpro4 PLX Wideband

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