ok ive been having this problem since i got the car and cant figure out what it is. USUALLY once the car reaches operating temp when im driving the CEL will come on and the code is for o2 sensor. i cant figure it out. i put a new o2 sensor on and it does the same thing. the motor is a d16y7 running on a pm6 ecu. theres 1 o2 sensor hooked up(single wire o2 sensor) and its on the header(DC sport). theres another one right before the cat and i thought maybe that was the problem because its not hooked up but i checked the pinout for the ecu and there is only 1 o2 sensor wire. im out of ideas of what could be wrong. its annoying because it seems to be running good then the CEL comes on and it bogs really bad until i turn it off and start it back up. then it will come on usually every few minutes but sometimes it wont come back on at all. hopefully someone can help me out here

 

anyone?

 

i have similar problems.. any help?

 

the car is either running so rich or so lean on the pm6 that the ecu thinks the O2 sensor is bad. The ecu may try to compensate for the reading by enriching or leaning out the fuel, but it can only do so much. If the ecu can't compensate for the big difference, then it thinks the o2 is sending bad data. You can chip the pm6 to ignore the o2 sensor and just read from the lookup tables, and is probably the route i would go. But then you need to get the car tuned.

that is all assuming that the wiring IS good on the car, which you said it was..

 

what else in the wiring should i check other than the o2 sensor, cuz the rest of it idk the guy i got the car from did it and he seemed like a jackass

 

also can i just run a wire from the o2 sensor straight to the ecu just to make sure theres no short or something in the wiring. sorry i dont really no anything about wiring or electrial

 

I been having the same problem too, my old O2 went bad, and I bought a brand new Bosch one, now it comes on every now and then, especially with cold weather...I luckily when I did emissions last month I passed, i think because the temps were warmer outside. running the same set up as the OP, i been running it for 4 years now btw, and now its doing this.

 

You absolutely can do that.. nothing wrong with it. That will give you more info than any of us can provide. If it still flips out after that with a new sensor, then the only problem can be that the ecu is freaking out because the engine isnt running even close to what it can control. If that is the case, then you should think about getting the PM6 chipped and then copy the fuel and ignition tables from a y7 or similar engine and use those on the pm6.

 

i thought the pm6 can run the y7 just fine tho?

 

Well, the d16a6 is a 9.1:1 compression engine while the y7 is 9.4:1 compression. I would be surprised if the fuel and ignition maps were *that* different, so I agree that a pm6 should run a y7 just fine. if your cat is clogged, then that may also cause the o2 sensor to flip out.. have you done a compression check on your engine?

how is the 1 wire wired right now? when you got a new sensor, was it a new universal one? or was it the plug and play 1 wire for a little more? because how you attach the new sensor matters if you used the universal style. The universal style need to use a crimping splice, because solder will just melt.

 

its a universal 1 wire sensor i believe, got it at napa. i connected it using one of those wire connectors that you crimp, and just connected it to the wire that was going to the old o2 sensor

 

also for some reason it seems like right when the check engine light is about to come on and im flooring it through the gears it seems to bog around 5.5k rpm and then the CEL light pops on and it gets power back again. and when the check engine light is on it will buck real hard at partial throttle until i let off or floor it.

 

Or perhaps there's something making the car run rich? Timing, map sensor, vacuum leaks...

 

I wonder if it is the crimp connection? Here is an idea. Chop out the crimp connection, then strip the wire to the ecu and from the o2 sensor. then put a crimp connector over one of the wires, and then wind the 2 wires together really well, then crimp over the wires wound together. The crimp portion might be too high resistance and could be causing the o2 readings to be off significantly.

The idea is really to wind the 2 wires together before you crimp. that way, it is straight copper instead of whatever is in the crimp connector.

 

have you tried to read the sensors voltage while WOT ?(refer to HELM) or just do a bench test, remove the sensor & torch it with propane, check it with digital meter, ground on the sensor body & red to the wire. You should have a reading shooting up when its hot, & quickly climbs down when you removed the torch.
I'm having similar problem as you, manage to tackle & change 1 faulty o2 sensor but now I have ecu throwing the o2 sensor, next -> going to replace it with new sensor & yes this o2 sensors CEL is really mind boggling lol....

 

they are twisted together then crimped

 

and also ive never messed with the ecu. how do i connect a different wire to the o2 sensor pinout? does it just stick in there or what?

 

would the car smelling really bad be running lean or rich? it smells like exhaust but alot worse than any other car ive smelled. also after driving it for awhile it starts to smell like somethings burning

 

i have a similar Problem.... when i start my car and just start going about a mile down the road ill throw a check engine light but if i let it warm up to the first line it wont do it.... i replace the o2 sensor and did NOT reset the ecu So idk if it was running in limo mode and dumping to much fuel and ruined it or what help?

 

Do you know if your cat is good?

 

nope ive never taken it off or anything

 

maybe check into that
BTW, solder ur connections whenever possible, it won't melt as posted above. We solder everything at the shop.

 

ok, this is one of the symptoms that your o2 sensor is bad.

 

I disagree only in the case of the o2 sensor. Everything SHOULD be soldered, but you can't solder the o2 sensor. The wiring gets too hot and melts the solder. Ask me how I know..

 

...how do you know ?
that bad smell id definately due to por A/F mixture, so far
1.) loose or bad vacuum line
2.) bad o2 sensor connection(but we can check the voltage at ecu pin plug.
o2 sensor#1 is pin16, 02#2 is pin 8)
3.) faulty 02 sensor.
4.) ??

this..
https://honda-tech.com/forums/honda-crx-ef-civic-1988-1991-3/b16-2nd-o2-sensor-900501/