New o2 sensor/ resulting problems

[Vash744]

Hi, I just installed a new o2 sensor, NGK brand. It seems run a little smother and idles nicer. Only...

Now my engine does weird things almost like a loss of power at certain times. Its really hard to explain, but when going down the road at a constant speed the engine will change rpms slightly, you cant see it on the gauges but you can feel it in the pedal and you can hear it.

I wanna say it might be something with fuel delivery but im not sure. Any ideas?

[**CB7**]

Hi, I just installed a new o2 sensor, NGK brand. It seems run a little smother and idles nicer. Only...

Now my engine does weird things almost like a loss of power at certain times. Its really hard to explain, but when going down the road at a constant speed the engine will change rpms slightly, you cant see it on the gauges but you can feel it in the pedal and you can hear it.

I wanna say it might be something with fuel delivery but im not sure. Any ideas?

Did you reset your ECU after installing the O2 sensor?

[HDuece2]

I would put the old O2 back on and see if it still does the same thing....That would eliminated weather or not it is actually the O2 you replaced.

[vietkid_2006]

Did you reset your ECU after installing the O2 sensor?

Yes try resetting your ECU.

just pull the ECU fuse.

[4GAccordH22]

I would put the old O2 back on and see if it still does the same thing....That would eliminated weather or not it is actually the O2 you replaced.

Dude! That's the 2nd post of yours I've seen today that makes no sense whatsoever.

To the OP, reset your ECU and drive it for a tank or 2 so it can relearn your setup. Then if the problem persists, dig into it to see what you can find.

[Masamune]

If you have a manual then you can skip the next paragraph, because I don't know what it is then

Too lazy to look, but do you have an auto tranny? If so it sounds like your torque-converter is being picky. My car does it that at 70+ and sometimes my RPM's will change ever so slightly from 3k to ~3.2k. It's annoying, but I don't feel like trying to figure out what the problem is.

[Vash744]

Yes try resetting your ECU.

just pull the ECU fuse.

Unfortunatly I have not done this yet. I knew it needed done after I replaced the o2 sensor, but procrastination got the better of me. I will try this and let you know how it goes the next time I get to drive it.

A big duh I should have known this moment hits me.

[deevergote]

It's not the ECU fuse... it's listed as "Radio/Bacup"... another option is to just disconnect the battery for a few minutes.

It's possible that your new o2 sensor is faulty. It's also possible that something else is causing the problem. Reset the ECU, drive it, and if your CEL comes on, pull the code.

[Vash744]

Thing is, that before I replaced the o2 sensor, it threw codes, but now its golden and doesnt throw codes. So doesnt that mean that its working correctly?

[cb7rush]

Thing is, that before I replaced the o2 sensor, it threw codes, but now its golden and doesnt throw codes. So doesnt that mean that its working correctly?

not necessarily..it could still have codes..before you reset your ecu check for codes...if you already reset it, then test drive it and see if your CEL comes on..

[Potatoswatter]

not necessarily..it could still have codes..before you reset your ecu check for codes...if you already reset it, then test drive it and see if your CEL comes on..

The old codes remain in the ECU until it's reset. He already knows there was an O2 sensor code in there, it will certainly be there still if he checks again.

The description sounds like normal torque converter lockup. Except that you *can* see that on the gauge. Engine RPM's changing but not showing on the tach means a broken tach.

[HDuece2]

Dude! That's the 2nd post of yours I've seen today that makes no sense whatsoever.

To the OP, reset your ECU and drive it for a tank or 2 so it can relearn your setup. Then if the problem persists, dig into it to see what you can find.

You must have a problem yourself if my post makes no sense to you!.....It's very simple. He didn't experience this problem until the O2 was changed. If he puts the old one back and the issue still continues, then he can eliminate the O2 as the cause. How does that not make sense?

[Masamune]

I would put the old O2 back on and see if it still does the same thing....That would eliminated weather or not it is actually the O2 you replaced.

VS

You must have a problem yourself if my post makes no sense to you!.....It's very simple. He didn't experience this problem until the O2 was changed. If he puts the old one back and the issue still continues, then he can eliminate the O2 as the cause. How does that not make sense?

I think he was referring to how you typed your first post. It requires some magic to understand, which I will now perform!

I would put the old O2 (sensor) back on and see if it still does the same thing....That would eliminated (eliminate) weather (whether) or not it is actually the O2 (sensor) you replaced (causing these problems)

See? Much better!

[Potatoswatter]

I think he was referring to how you typed your first post. It requires some magic to understand, which I will now perform!

It's also unsound advice. The O2 sensor is a computer input, and the ECU is supposed to compensate for sensor age, so an ECU memory reset is a good idea recommended by the manuals.

Furthermore, swapping the sensors can be a pain, and involves some risk of damaging them. And if the old sensor was bad, the car was doing things wrong anyway. More likely OP is describing the normal tendency to drop a few RPMs under low strain.

[deevergote]

If the ECU was reset and is not throwing codes, then the o2 sensor is most likely NOT the problem any longer. If you're still having problems, the cause is probably something else. And something that doesn't trigger a CEL code. However, I only get a CEL after I hit highway speeds, and I'm quite certain that my problem is the o2 sensor. I compensated with a richer fuel map (chipped ECU... I cheated...)


Take the car up to about 55mph, and rev it over 4500 (after it's warm, of course!) See if a CEL pops up then. If that happens, it's very likely code 43, fuel supply system... which is often (but not always) the o2 sensor. If that happens... see if you can return that o2 sensor for another one, as that one might be defective.