this is the prob. i just did a full exhaust swap on my 94 cx h/b.
dc 4-1/test pipe/invidia cat back
ever since the install of the exhaust, my cobalt a/f moves slower then before.
it was reading rich 4 like 4 days, now it reads way 2 lean. wtf?
so i unpluged my o2 sensor 2 rich it out some. i drove my car 2 work (45min drive)
and no cell but my idle is bouncy now. up to 1500 down 2 800................
any1 have a clue on wtf is going on?

its a stock d15

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DISROK1 &raquo;</TD></TR><TR><TD CLASS="quote">
so i unpluged my o2 sensor 2 rich it out some. i drove my car 2 work (45min drive)
</TD></TR></TABLE>

not a good idea. is that a wideband o2 sensor you unplugged? If its a stock o2, you can't trust your guage's readings to be very accurate.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by IHateJDM &raquo;</TD></TR><TR><TD CLASS="quote">not a good idea. is that a wideband o2 sensor you unplugged? If its a stock o2, you can't trust your guage's readings to be very accurate. </TD></TR></TABLE>
^^^
What lead you to believe unplugging the o2 will 'rich it out'??

 

the stock o2 sensor. unpluging it would put the ecu in limp mode/safe when it see's the cell right???????????????????????
so if it does it sends more fuel 2 the motor???????????

 

it retards timing more than adding fuel. plug your o2 back in. I doubt you are actually running as lean as you thought. You can't tell without a wideband o2. Could you hear detonation?

 

All it does is sends the car into looking at the fuel tables directly without feedback from the O2 sensor. Keep the O2 sensor plugged in and you will be fine.

Last time I checked pulling the O2 sensor code didn't put you in limp mode.

 

so why didnt the ecu throw a cell,
when i drove the car with it unpluged?
and the exhaust was back firing.

 

1 more thing why the bouncy idle????????????
after unpluging the o2 sensor?

 

bump 4 tech support?

 

Your car should throw a check engine light with it unplugged. It could have a bouncy idle because of the crazy rich way that it is running without the 02 sensor, since it is reading directly from the map, or is getting 0 volts so it is compensating to much in the feedback it is getting, I forget exactly how it works.

Your best bet is to check and see if your CEL is even working. Try unplugging the Map sensor and see if it throws a CEL. If it doesn't your CEL isn't working. And seriously keep you O2 plugged in.

 

so why is it still bouncy after i pluged it back in????????

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DISROK1 &raquo;</TD></TR><TR><TD CLASS="quote">so why is it still bouncy after i pluged it back in???????? </TD></TR></TABLE>
Did you mess something up during the install?
Accidentally unplug a vacuum or sensor..?

I've had a bad o2 for a while now.. and I've never had idle issues.

 

car was cool untill i pluged the o2 sensor back in.
like i said b 4 i unpluged the o2 sensor 2 see if i would go in 2 limp mode and see a cell, but it did not throw a cell????????
so i pluged it back in and bang!!!!!!!!!!!
free bouncy idle

 

i take it no one has a clue???????????????//

 

You need to do some more investigation on the car. I would go out and drive it a little, and reset the ecu. See if it goes away. Sometimes it will honestly "magically" go away.

 

unplugging your o2 should throw a cel. your o2 shouldn't change your idle. I think you have wiring issues. Do you have a vafc or anything installed?

 

the car is stock !!!!!!!!!!!!!
still has the 1.5
no safc
i guess i will reset the ecu and run it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by IHateJDM &raquo;</TD></TR><TR><TD CLASS="quote">unplugging your o2 should throw a cel. your o2 shouldn't change your idle. I think you have wiring issues. Do you have a vafc or anything installed?</TD></TR></TABLE>

The O2 can cause pretty odd idle problem actually. But a properly working one will not.

 

^^^^^^yes.....a bad o2 sensor will cause an erratic idle and can make you run lean

 

Put your o2 back in. Ditch that A/F gauge cause it is not accurate at all and if you want a A/F gauge get a wideband such as the PLX M300.

With your o2 removed you will be Running rich with slight igntion retard and engine performance is defiantely hurt by this. It is also called LIMP mode.

 

update
when i did the header i extended the o2 wire.
i never got the wire 4 the dc relocate.(from the top of the header 2 the bottom)
so today at work, i had no cars 2 work on which means time 2 pull the hatch in 4 a
quick fix.
i cut open all the loom on the stock harness, cut the o2 wire back 2 fac spec then rerouted it and reloomed it.
seem 2 be running better.
the a/f seems 2 read better also.

 

with the PLX M300 u can replace the stock o2 with the wideband o2, then send the output of the unit 2 the old o2 input for the ecu?
so the ecu thinks it still has a narrow band o2 right???????????

 

any1??????????????????????
im sorry that im not asking what color u all think i should paint my car.
cause that would get like 300 replys within like a min.
any tech input would b nice.

 

dude. it was 2 in the morning. I know I am not on here then...

Get a grip.

You can use the PLX M300 to simulate the narrowband output of a stock o2 sensor. It is very easy to do. You just splice it right in to the ecu plugs and you are done. It is good stuff.

I have heard stories like yours, where people extended the wires but used wrong gauge wire and added resistance or something to the circuit, which caused the readings to be way off.

Right from PLX's site.

"Can the M-Series narrowband output be used to replace my stock oxygen sensor?

Yes, if your vehicle comes equipped with a standard narrowband oxygen sensor, you can use the narrowband output (gray wire) to feed that directly into your ECU. This eliminates the hassle of having to weld a second oxygen sensor bung onto your downpipe. PLXApp004 contains more details. "

http://www.plxdevices.com/M-Series_FAQ.htm