Hondata

Issues:
At Idle:
PLX reading: 13.5:1
RomEditor: 13.5:1
Voltage: 1.70 volts

Accelerating:
PLX reading: 13.6:1
RomEditor: 13.0:1
Voltage: 1.45 volts

Cruising:
PLX reading: 14.4:1
RomEditor: 13.4:1
Voltage: 1.65 volts

It makes sense that the RomEditor matches the voltage as the Hondata gets its input from the PLX. I have the correction value on the PLX setting and have also tried 9.995 / 19.995 as well as numerous other values. I have done all the checks on the PLX. Car off, key on, voltage is at 2.35 volts for 14.7:1. O2 removed, voltage goes to 5 volts and AIR/Lean on the controller. I have the power(Red wire on the PLX) wired into the IGP2(B1 OBD1 side) on the harness that I built and have tried the Ground to both the PG2(A24 OBD1 side) and also a chassis ground. I have tried zero, 1 and two capacitors inline with the ground and white wire. I have the white wire installed on the PHOS(D14 OBD1 side) on the harness. I can lean out the car to 15.5 while cruising momentarily and the car will start to hesitate and confirm what the PLX display is reading, but the Romeditor will still read around 13.6-14.1:1 and the voltage will match that. This is throwing my recorded lambda values way off and I really don't want to trust them. Any help you can bring will be good. Thanks!!!

Jason

Disconnect the PLX from the ECU and measure the analog output to see if the ECU is pulling it down. The later PLXs should read 1V at 10:1, 2V at 20:1

With the PLX connected to the ECU measure the voltage on the ECU pins between D14 and D22, and check this is the same as the voltage as measured between the analog output and analog ground on the PLX.

Then measure the voltage between D22 and chassis ground, and check that it is close to zero.

The most common problems is using a heater ground rather than the signal ground (D22) and having a dirty connection in the wiring harness.

Hondata wrote:Disconnect the PLX from the ECU and measure the analog output to see if the ECU is pulling it down. The later PLXs should read 1V at 10:1, 2V at 20:1

With the PLX connected to the ECU measure the voltage on the ECU pins between D14 and D22, and check this is the same as the voltage as measured between the analog output and analog ground on the PLX.

Then measure the voltage between D22 and chassis ground, and check that it is close to zero.

The most common problems is using a heater ground rather than the signal ground (D22) and having a dirty connection in the wiring harness.

Everything checked out with the PLX voltage. I confirmed that I had the same voltage on D14/D22 setup. On the ground readings from D22 to chassis I was getting 50mv.

I removed the Hondata and installed it into my stock 96 civic. I made a base map, installed the PLX in the manifold and drove the car. The readings were dead on. I had no issues there. So I went back to my 00 turbo civic and started removing things. I removed my alarm thinking there was an issue there. Didn't fix it. I am going to remove my engine harness and check everything out there. In my hondata setup, I am running open loop and disable O2 heater. Also, I still have my stock O2 sensor installed down near where the cat would be. It is also still connected as well. What would make the VOLTAGE readings from the PLX, which correlated with the Hondata readings when you convert the voltage to AF, to be off? Should I try wiring the plx to the battery and to the chassis ground and then run the white wire directly to the ecu removing all the O2 sensor wiring? I am just stumped. Thanks.

Next you could try wiring the PLX directly to the ECU.

I had a similar problem with my 95 Civic. I started to trace the voltage drop from the o2 sensor connector to the ECU, then found that half way through checking voltages the problem fixed itself. It turned out that I had a dirty connection in the engine bay, and unplugging and replugging the connector fixed the problem.

Otherwise, use a fixed voltage source across the o2 sensor connector to check that datalogging shows the same voltage. You can use an adjustable voltage source for this, or even a 1.5V battery for a quick check.

Hondata wrote:Next you could try wiring the PLX directly to the ECU.

I had a similar problem with my 95 Civic. I started to trace the voltage drop from the o2 sensor connector to the ECU, then found that half way through checking voltages the problem fixed itself. It turned out that I had a dirty connection in the engine bay, and unplugging and replugging the connector fixed the problem.

Otherwise, use a fixed voltage source across the o2 sensor connector to check that datalogging shows the same voltage. You can use an adjustable voltage source for this, or even a 1.5V battery for a quick check.

Found the problem. The stock O2 sensor was still connected down on near the cat location. This sensor was bad. I unplugged it and right away....proble goes away. I installed a known working O2 sensor and it worked fine. So the if the stock O2 sensor is still connected and in the exhaust system, it has to be working properly. Also, if the stock O2 sensor is not connected in the exhaust stream, the voltage readings will also be off.

Jason

The stock o2 must be unplugged if using the wideband input into the ECU.

Hi,

Can poor connection be the reason that the air fuel ratio is not working in RomEditor while datalogging? And that the O2V shows always 3.7-3.8?
All other sensors work perfectly.
Thanks,

Andreas

3.8 V usually means that there is no connection from the ECU to lambda meter at all.

Thank you very much.
So a connection/wiring issue. Can you please confirm the pin where to connect the wideband linear output? (I have a Hondata made P28)
BTW, I spoke to Matt yesterday and he told me that I have to connect that white wire instead of the grey narrowband output into the ECU. Hoped that would fix the problem but it does not.
And strange that it did work once and then it stopped. If I connected the wires wrong, it would have not worked at all.
I will check again. What I did was connect the ground to one of the bolts of the ECU mount on the chassis and power together with another gauge.
However, I do not think ground or plus is poor, otherwise the PLX controller would not work, am I right? The PLX controller works fine.
Yesterday I did also check the voltage at the place where I cut the o2 wire on my P28. It was between 0,1 and 1,0, but okay, that was due to the fact that the narrowbandoutput was connected.
Anyway, this shows that the ECU gets the o2 information but does not "read" it.
My only hope is now that the adapter wiring harnes has been made wrong.
I do also suppose this because when I plug off the sensor wire I do NOT have a code thrown.


@JKOBD,

Sorry pal to misuse your thread. Please have understanding for a desperate guy from Germany which nobody could help so far.

Have you checked continuity on all your connections and the car's wiring harness?

Guys,

Am a very happy man again. Thanks a lot.
It was the adapter wiring harness. The o2 sensor wire was not even connected to the ecu. Now I got rid of that harness and everything runs perfect. Many thanks again.

Kindest regards from Germany,

Andreas