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trusty rusty ED6
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Discussion Starter #1
my setup:
D15B1 block
D15B head
91 civic hatch
P28 ECU
P.O.S. intake
eBay catback

my problem:
when i bought the car the mini me had already been done. all the wires were run etc. it was a decent running car except it was showing Code 1 for the O2. i bought a new O2 sensor for it back in march (when i got the car) cleared ECU and still had Code 1. i pulled the engine harness and re-soldered the connections for the O2 sensor, put it back in, cleared ECU and still have Code 1. then i checked all four O2 wires with a volt-meter to make sure they were flowing electricity like they should. everything checked out. i even verified 12volt and ground signals. then i double checked to make sure all the wires were going to the right places. they are. still. . . Code 1. it shows Code 1 after i reset ECU before i ever start the car. i'm pretty convinced there's something wrong with the ECU itself but i want to pursue every possible option. so. . . any thoughts to what could be my problem? i should add that since i pulled the harness and re-soldered it does a "wa-wa-wa-wa" quick surging thing when i crack the throttle. it idles okay. i mean, as okay as a car with no O2 would. and if you open the throttle a bit more it runs nice and smooth. it's only at part throttle that i have an issue so i know it's mechanically sound. also i've already removed and cleaned the IACV but after running with the odd part throttle surging for a few minutes it throws Code 14 for the IACV. i'm pretty sure that's a symptom not the cause as i never had a problem with it before i pulled the harness and didn't do anything with those wires while it was out. i know this is a bunch of info but i'm thoroughly lost. i've done everything i know to do and i've gotten exactly nowhere. btw this is my first honda and i'm learning as i go so if the solution is really obvious and i'm missing it please be kind :(
 

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trusty rusty ED6
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Discussion Starter #2
really i'm just trying to figure out why my O2 sensor isn't working. maybe i should've posted this in the "Engine Management"? what do you think mods? move it over there?
 

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how is code 1 o2? when i had my p28 with code 43 taht was for o2. code 1 is oxygen content whatever that means not o2 sensor. u should really try that ecu in another honda
 

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Code 1 has and will always mean a problem in the primary Oxygen(o2) Sensor circuit in Honda's not matter the OBD or model. Code 43 is Fuel Supply System, which could be many things but probably a problem with the Oxygen(o2) Sensor circuit.
 

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trusty rusty ED6
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Discussion Starter #6
hey wow. that's EXACTLY the info i needed. thank you so much. gonna borrow a volt meter tonight and check it all out. btw, just to be sure, the [email protected] and main [email protected] are the only O2 wires that go into the ECU right? the 12volt and ground go elsewhere correct?
 

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hey wow. that's EXACTLY the info i needed. thank you so much. gonna borrow a volt meter tonight and check it all out. btw, just to be sure, the [email protected] and main [email protected] are the only O2 wires that go into the ECU right? the 12volt and ground go elsewhere correct?
A26 is the ground for the heater and D22 for the signal.
 

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hey wow. that's EXACTLY the info i needed. thank you so much. gonna borrow a volt meter tonight and check it all out. btw, just to be sure, the [email protected] and main [email protected] are the only O2 wires that go into the ECU right? the 12volt and ground go elsewhere correct?
naw i think alll 4 connections go back to the ecu. check this diagram it has all the pinouts in detail https://docs.google.com/document/edit?id=1YryLHIoEgzgKnXOvVycRNvazuTWmoh683L_-mOcUorA&hl=en
 

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trusty rusty ED6
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Discussion Starter #9
camdizawg - yeah i saw that, it's what i used to get where i'm at so far. but i didn't see a place for the 12volt wire for the O2. and i didn't know which ground to use. . .

hondaDNA - so now i'm confused. the four wire O2 sensor has one ground wire (green/white) is that what goes to A26?? the jumper harness that came with the car has the 12volt and ground wires that come from the O2sensor going back towards the engine bay. i just assumed they went to a ground and 12volt signal somewhere. does that not sound right? sorry for all the questions i'm REALLY wiring retarded and i'm doing the best i can to learn as i go.
 

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trusty rusty ED6
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Discussion Starter #11
stock signal wire is adios. all four O2 wires are running from a factory connector back to the jumper harness (pretty sure it's from Boomslang) from there the signal wire goes to D14, heater to A6, Ground spliced to another (presumably) grounded wire and 12volt to another (presumably) grounded wire. so basically i've already got what you're saying i should have.
 

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The Wife and the Car
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The heater ground and the sensor ground are not common.
Dont make the mistake of assuming they are.
The Heater Ground is pulsed on and off after about 45 seconds of you starting the engine.

Most O2 errors. Will not come on the second you start the car.
If your O2 is throwing a code the second you start up the engine then its a fault with the ground and +1 Volt NB signal.
If your O2 is acting up because of a heater issue. Then you can start the car and drive it for a good 30 seconds before the O2 sensor throws a Cell.

The reason for this is because of the way they have implemented the code in the ECU.
When you turn the Ign on they first check the NB signal and Ground. And right away start pumping 12 volts to the heater. Then after about 40 seconds they stop pumping 12 volts the heater by opening the heater ground and they check the resistance value they get. If the resistance value is outside what honda expects it throws a code.
If its inside what honda expcts it then takes a call as to weather it needs to pump more power to the Heater or not based on the resistance values it sees.

You can still get a busted Heater sensor to work. You do this by hooking up a LED with a 1K resistor between the Heater + and - and then watch that LED it should light up 45 seconds after you start the engine and start blinking. The ECU will think the Heater is ok. And will then just monitor the voltage output from your O2 sensor.
It may run like shit for a few seconds but as honda keep their sensor so close to the engine the heat from the engine brings it up to temps and it works like a regular single wire O2 sensor.
This is how it is on my Honda D15 Block with y8 head.
 

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trusty rusty ED6
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Discussion Starter #14
well i didn't hook it up at all. it was all like this when i bought it. i'm not blindly trusting the boomslang but far as i can tell it's all where it should be. the O2 sensor itself is new (bought by yours truly) and unless it got fouled by gas in the less than 300mi i put on it since install i doubt the sensor is bad. which is why i'm starting to think maybe my ECU is the culprit but that just doesn't seem right to me.
 

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trusty rusty ED6
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Discussion Starter #15
rdc - according to what you're telling me then it's a ground issue. which makes total sense. that was my original theory but since i'm dumb with wires i wasn't sure what to do. here's where i get confused: if the heater and signal have separate grounds why do i only have one ground wire in the 4-wire group??? how am i supposed to ground this thing?

i'm sure i'm overthinking this and i REALLY appreciate you all trying to get though my thick skull and help me figure this out!
 

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You don't have one ground wire in the group, you have TWO(2), one is for the heater and the other is for the signal.



The positive(+) terminal to the heater is at A6, the ground or negative(-) terminal is at A26. The signal(+) for the pump cell is at D14, the ground(-) for the pump cell is at D22.

ground it at thermo housing or where ever
snag a 12 volt source some where
then use your stock signal wire. then run the heater to you jumper
Not good info...
 

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trusty rusty ED6
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Discussion Starter #17
So because the circuit isn't being completed inside the ECU it's not being recognized? Because THAT makes sense to me. i'm at work now but planning on trying this when i get home
 

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trusty rusty ED6
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Discussion Starter #19
alrighty. . . got home and checked how everything was routed. my sensor ground is spliced to a wire going to D22 (like it should be) and my heater ground is spliced to a wire going to A25 (i've seen different places say A25 and A26 equally. no idea which is actually correct) i haven't had a chance to borrow a volt meter today so i won't be able to make sure juice is actually getting to those ECU locations till tomorrow. this is driving me fucking crazy. thanks again to all of you for your help.
 

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trusty rusty ED6
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Discussion Starter #20
well i checked continuity and there's no resistance - which means i've got good connections. so i went to start the very thorough flow chart HondaDNA posted and i realized it said i needed a "test harness" between the ECU and connector. i don't know what that is. and i definitely don't have one. anybody know what that is or an alternate way to perform the test described in the flowchart???
 
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