I ran into a problem with some wiring and was wondering if you could assist me. I made a post but with no avail.

I have a 98 civic HX (obd2a) harness and it has the upstream pre cat 7wire wide band o2 sensor, and downstream post cat 4 wire narrow band o2. I have a h22 p28 phearbile chipped w/ o2 (obd1 stepdown).

How do i make this 7 wire o2 to 4 wire o2 conversion, and or... make my secondary 4 wire o2 sensor pinned out as the primary...

I found this... http://www.hybridautomotive.com/tech/o2/

I do not know if it will work since it is for an OBD1 car...

 

I did this coversion on a vx not an hx, But im sure you can use one of those extra o2 wires

 

--- the 7 wire seems to have the same color wires as a 4 wire but then has the additional 3... I was thinking if i cut the 7 wire plug off, solder on a 4 wire plug... use the correct 4 wires, and cap the 3... would that work?

was also thinking...

Can i use the secondary o2 sensor which is a narrow band 4 wire o2, and just repin it @ the ecu to make it the primary o2?


KS problem... forgot p28 doesn't use a KS "banghead".

 

tttttttttttt.

 

You dont have to cut off the connector you can just depin it, it will save you a ton of work. Then just insert them into the new connector and hook up the o2.

 

--- Yeah but what 4 wires of the total 7 wires do i use, and what do they go to on the sensor?

Also check out the link i posted up top. Its a 7 to 4 wire conversion, but it is for OBD1... Since i am obd2a, can i still use it? (idk if there is differences between OBD in o2 sensor department)

 

You need to look at schematics from the hx and from an ex compare and swap the wires around to make the hx harness resemble the ex one. Id have to look at schematics from obd1 and obd2 to give you a positive answer but im sure you cannot use that obd1 conversion so i would not recommend it.

 

--- I was talking to john @ phearable and he directed me towards the obd1 diagram too, and i was kinda stumped thinking... i have an obd2a harness, shouldnt i be using obd2a diagrams?

Where can one get said diagrams? Besides for purchasing the books :D Was really hoping the o2 sensor colors would be the same from obd1 to 2a...

When wiring an o2 sensor and looking for the pin outs, im looking for what exactly?

Heater, 12v, ground, heater?

 

Heater, heater control, ground, and 12v constant

 

I think by reffering you to the obd1 diagram he was just giving you an idea of what needed to be done. As for the schematics try google images obd2 civic o2 sensor wiring schematics.

 

What are your thoughts on repinning my secondary 4 wire o2 sensor, to the primary o2 sensor locations?

These are the obd2a specific threads i found on o2 sensor wiring...

http://www.eastcoasthondas.com/tech-...sor-conversion

https://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/5wire-4wire-oxygen-sensor-help-also-obd2a-obd1-question-1275659/

 

Im sure that sensor will work in that location but you would still have to do the conversion because im sure the obd jumper harness will just delete that secondary sensor.

 

--- Yeah i am saying... Say the primary o2 sensor with 7 wires is A1, A2, A3, etc to A7. The secondary o2 sensor with 4 wires is B1, B2, B3, and B4.

I remove A1-A4, and remove B1-B4... Then place B1-B4 into A1-A4 locations. A5-A7 will be unused since its wideband specific.

 

Yes, Im sure that will work!

 

Haha, was thinking about that and wasn't sure if it made sense... I am going to go out on a limb here and say... That obd2a harness is going to have the same pinout to ecu for 4 wire.

If you happen to find the pinout for the 7 wire o2 sensor, please send my way. Once i get that... It's as simple as just swapping out some pins from secondary to primary and then extend the plug to my header.

 

Actually now that i think about it... The pinouts for primary and secondary should all be the same between obd2a... The only thing different would be the "added" 3 wires... Which will be unused anyways because of the stepdown.

 

Lol i have them, but i just got done moving so i have absolutely no idea where they are.

 

--- Am incorrect for assuming this?

 

I think you are right!

 

This may help a bit

http://6thgearadvertising.com/civic-...nd-wiring.html

 

Okay so this is what i got... Correct? Also... As i said... Swapping SECONDARY PINS to PRIMARY LOCATIONS... Should work?


OBD2a Primary O2 Sensor Pinout: (HX 7 Wire - Leave Remaining 3 Untouched/Unused - Use NEEDED 4 Below)
Location: A06 Function: Primary O2 Heater Control Color: Black/White (OR) Orange/Black
Location: A24 Function: Power Source (IGP2) Color: Yellow/Black
Location: D07 Function: Primary Heated O2 Signal (PH02S) Color: White
Location: D12 Function: Sensor Ground (SG1) Color: Green/White (OR) Green/Blue

OBD2a Secondary O2 Sensor Pinout:
Location: A05 Function: Secondary O2 Heater Control (S02HTC) Color: Black/White
Location: A11 Function: Power Source (1GP1) Color: Yellow/Black
Location: D14 Function: Secondary Heated O2 Signal (SH02S) Color: White/Red
Location: D11 Function: Sensor Ground 2 (SG2) Color: Green/Black

 

Spoke to the local tuning shop for a second opinion before i got into it... They verified that everything should work fine with what i wanted to do.

I re pinned everything today and it was all fine except for 1 small problem. When i got to D11 and D12...

D12 was a larger pin size
D11 was a smaller pin size

So the D11 went into the large pin location fine (was a bit snug when plugging the step down into it)
D12 didn't go in at all and ended up messing the pin up trying to get it in. I tried crushing it some to squeeze it in, and that didnt work because the pin wouldn't go in then.

So i ended up taking off the pin from the wire, and left myself with a bit of wire exposed, used a spare pin from other harness's i had laying around (small pin)... I crimped it back over the wire, and then soldered it on so it was secured well.

Pushed the primary pin into the secondary slot with the new/refabbed small pin... and clicked right in... Closed the security tab and it all worked perfectly.

Once i get done painting the engine bay and put the motor in... hopefully i get no CEL's.

 

Sweet! Post the final results when your all done please

 

Well what i did above... WORKS! So happy this wasn't a headache. I had a code 9 cyp problem from dizzy but bought a brand new td89 dizzy and solved that. No o2 sensor problems at all.