Car: 91 Civic, D16A6
JRSC Stock Pully
DC Header
2.25’ Exhaust (Cat Back)
Fuel Pressure (tried many different settings, right now at 46+Psi)
Code: 1 (o2)

Can a bad catalytic converter cause an O2 Code, even if the sensor is before the CAT? 02 sensor was relocated to just before CAT with no issues on the NA motor. After JRSC install, got an O2 code after a day or so of driving.

I have changed O2 sensors a few different times. Changed and regapped plugs. Change fuel pressure (tried going lower and now higher) and today I redid the connections in the sensor to the wire that extended it. Car drove great for a while today, then tossed the O2 again. I am extremely frustrated, and am looking for any help I can get at this point. Any suggestions, please toss them out there.

If anyone thinks it will help, I am going to try and put in a hollowed out cat tomorrow. Any thoughts? I don’t see how this would help if the O2 is BEFORE the cat, but it’s the last idea I have…….

 

Nope, I don't think it will. As long as the exhaust is still escaping, I don't see how a cat could cause an 02 code. Trace your wiring, make sure it's good from the 02 sensor to the ECU.

 

Arrrrrggggggg.

I was hoping that wouldnt be the case. Wiring is not my strong point.

Ill have to take a look and see what I can find out. Oscar Jackson had mentioned somthing about a "static" sheild on the dizzy, he thought that may be the issue, but we will see. Anyone else have any suggestions, feel free to toss them out there!

By the way, tell Joe, Eli, Randy, Regan, Matt and all those guys I said hi!

 

How you can tell if its your cat you can put a test pipe in there or just gut it, I live in MN we dont have emissions ne more so i gutted mine plus the **** inside of the cat is worth money its platnum.

 

I've got a gutted car I used years ago. But I dont see how the cat, which comes AFTER the O2 would make a diffrence, so I thought I would ask.

The really odd thing here is I swear its tossed the code after I hit bumps in the road. And I know for a fact that it has cleared the code a few times after hitting bumps as well. Maybe its even a ECU issue? Anyone ever had or heard of this before? Rough roads making codes?

 

A bad or plugged cat can cause an o2 code

 

Jedb18

Can you give me an idea of how? I dont understand how that’s possible if the O2 is located before the CAT itself.

I dont expect an engineering lesson, but a brief explanation would help!

Is it because of a "backing up" of gasses and a loss of the proper scavenging effect? In turn this leaves the exhaust gasses sitting over the O2 sensor and contaminates the reading? That’s seems to be the only explanation if the CAT was at fault, and this would mean the code should disappear if a hollow cat was installed, correct?

 

i am wondering if your problem is the same as mine because i have had the stock D15B2 with dpfi, then went to mpfi on that motor, and then went to a sohc zc and the whole time my car has thrown an o2 code. The o2 sensor has been changed and when i did the motor swap every sensor has been changed except for the map and the baro sensors.

Does your code switch on while cruising for awhile under a normal engine load and when put under a heavy engine load? Mine does this and when i shut off the key it goes away until the situation described above is met again and then it throws the code.

I am very interested in how you end up solving the problem because it has messed with me for 6 months.

Let me know if these are the same problems you are experiencing.

 

To mee it sounds like you ar running into a bad O2 again. I would check if you are dumping fuel.

What you are describing is that when you get it into "open loop" (higher RPM usually on the OBD0 cars) it then begins to read and control your fuel from the O2. I am guessing you would get almost the same effect by just removing your O2 sensor all together and then running the car. Switch your O2, find out if your running pig rich, and I am guessing that will solve your issue.

As stated above, mine seems a little more random. I can hammer the car doing 7K RPM with 6Lbs of boost for an hour and nothing will happen, then for no reason, the code hits. It also seems to come up with heavy bumps, and I know Ive seen it go away after heavy bumps.

I am guessing it will end up being wiring, or the "Static" sheild that oscar talked about. I will be trying a diffrent ECU as well. ANyone with any other thoughts, please feel free to chime in!

 

well the thing is that it usually happens when i am cruising at 50-60 mph which is usually when i am in 5th gear and revs are at like 2000-2500 so it is making me wonder what the problem is.

When i step on the gas you can smell the fuel coming out of the tailpipe but other times you cant.

I also did check the fuel supply system how it said to in the manual and it was pumping the correct amount of fuel for the 10 seconds i ran the pump.

I guess it could be the o2 sense i switched the one that was in the car from the d15b2 after the sohc zc swap with the one that came with my zc so i guess it is possible that both of them are bad.

One quick question for you though. On my harness for the mpfi that i got the o2 wire had been cut so i connected a new one from there on. The problem is that where it had been cut the copper wire looks like it was shielded by a white colored insulator and then by silver wire strands (like a seperate wire) around that and then the black wire insulator on the outside. When i connected the new wire i hooked it to the copper so could that shielding that was there be my problem since it doesnt go as far down the wire as it used to? I am just curious if you know anything about that or if i should be to concerned about it.

 

I had someone mention to me about the shielding as well. However, because of my header, my O2 was relocated with an unshielded wire for over a year with no problem. Once the Super charger went on, I started getting issues. My personal opinion, shielding that wire wont make a difference, but someone else my have a different opinion on it.

Anyone with any ideas, fire away!

 

I used to work for GM and on alot of the V6 and V8 engines I ran into codes for the various O2 sensors and most of the time it ended up being a bad cat, now I have never run into it personally on a honda so i may very well have put my foot in my mouth on this one

 

I had a bad cat on my old b16 swap and I got the code 1 as well. To check you cat you can do 2 things. You can see if your cat is pluged by hooking a vacume gauge up to a vac. port (althought since you are supercharged I dont know how you would do it) when you rev your vac. should drop, if it raises you have a exhaust restriction. Another CAT test we use is do take a temp gun and aim it at the beginning and after the cat. The temp should increas 15% if that cat is workinjg corectly.

 

I still think this will be a wiring issue now, but I am going to swap the car as soon as I get the chance with a hollow one. Although I leave it that way, it should clear the code if the cat is the problem. From there it will be performance CAT shopping time..........

 

The wireing is easy to check. Check to make sure the wire is going to the correct pin at the ecu. Than unplug the ecu, enplug the o2 sensor, t-pin the back of the harness connector and ohms the wire going from the ecu to the 02 and see if you have a break in the wire or high resistance.

-Chris

p.s DO NOT ohms the wire with the ecu connected,

 

Well I got the "static sheild" that Oscar Jackson had sugested may help from Honda. So I am going to try that. I dont think it will be the answer, would kick *** if it was though.

After that I will be putting in the hollow cat, and then checking the wiring and pins in the ECU side of the plug. Fingers crossed.

 

I tried the "static sheild" (honda cause it a drip gaurd), no diffrence. I will be changing over the cat this week, and then the checking the wires when I get a chance.

 

Put the old Hollow CAT I had sitting around in, and no change (other than the brutal smell and the obscene noise) still getting the O2 code one.

So now we move on to checking the wires in the harness, where I think I am going to find the issue.

Lets hope so!

 

Good luck, sorry I wasn't more help

 

dont buy a cheapo o2 sensor. make sure to get a factory honda o2 sensor. ive heard nothing but bad things about the longevity of the bosch ones. (mine is a cheapo that seems to be working, but i havnt checked my ecu for a code 1 since the swap... )

are you resetting your ECU before you retest things?

good luck

 

you said that you plyed with the wiring and it went away. i suspect that is the culprit.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by welfarepc &raquo;</TD></TR><TR><TD CLASS="quote">
are you resetting your ECU before you retest things?

good luck</TD></TR></TABLE>

I second this.. i skimmed most of the thread for the ecu reset.. but i havent seen it.. when you replaced the O2 sensor, did you pull power from the ecu for 10 seconds to clear the code?

 

Ecu is getting reset every time I do anything to this car.

Right now the O2 I am using is an NKG unit and I have never had a problem with them before. I have been told by several people to not both with the Bosh Units at all.

In the end it still may be the O2, but at this point point I am leaning towards wiring.

The Odd thing is, even if the code hasent poped up yet (dash light isnt on) and I am driving the car, if I hit a large enough bump, the check engine light will somtimes pop up for a quick second. WTF is that all about?

I think maybe one of the pins is loose, we will see.

 

Check https://honda-tech.com/zero...age=6 for the solution to the problem!

 

yeah that hitting a bump thing is really really weird. definitely sounds to me like wiring