Can an O2 sensor be bad without throwing a CEL?

[horizontalkev]

Is that possible? I have bad gas mileage, puffs of light black smoke (rich), on cold startup (40F) crappy narrowband is solid lean for a minute then once warm does the normal bouncing around, random shaky idle mostly when not warmed up (rpms don't jump much), sometimes jumpy on heavy acceleration, and feels low on power. Only CEL I have is P1105, fuel pressure solenoid malfunction.
Thanks

 

[ChiTownHussla]

Make sure the song I plug is all the way seated and yes I know to can be bad without trying to check engine light

 

[horizontalkev]

Make sure the song I plug is all the way seated and yes I know to can be bad without trying to check engine light

The song I plug? Could a bad o2 explain my problems?

Maybe I should try flipping that random switch I found, .

 

[MJBean420]

Bone stock or mods? I didnt see anything in your profile.

you do a BLT yet?

You check fuel pressure yet because of the code?

Try unplugging the sensor and see how it affects the engine.

Any tuning/logging tools? or just a crappy narrowband?

 

[horizontalkev]

Bone stock or mods? I didnt see anything in your profile.

you do a BLT yet?

You check fuel pressure yet because of the code?

Try unplugging the sensor and see how it affects the engine.

Any tuning/logging tools? or just a crappy narrowband?

Not bone stock, 6 bolt swap, 3in turbo back exhaust, cold air intake, walboro fuel pump w/ rewire, battery relocated to the trunk, T28 turbo @ 17PSI, tail bov atmospheric, maf-t, as for motor internals Im not entirely sure.

BLT? Burgerkings bacon lettuce and tomato sure sounds good. But no, I haven't done one yet will soon though.

I have a FP gauge, but how do I get an accurate reading, at idle? It usually is around like 37PSI at idle and wot I believe just over 40. I have notice sometimes my fuel pressure drops immediately after shutting off car, to just under 35.

Will I notice an immediate difference unplugging the o2 sensor?

I have PDA for logging I just need a New battery. As of now all Im using is the android App called Torque.

Thanks

 

[95tsiawd0330]

Yes my o2 sensor went bad on me and I got no cell just my wb reading rich at idle then it would start to bounce around on the gauge

Also someone let me know it I'm wrong but if you unplugged your o2 sensor when your car is running it will mess up the calibration then you will have to recalibrate it that's if your running a aftermarket WB

 

[WES_393]

Yes, O2 sensors become "lazy" over time. The sensor reacts to AFR changes slowly and/or incorrectly. But this is the one place a narrowband gauge is actually useful! A badly worn front O2 sensor would be obvious with a narrowband gauge tied into it. At idle, the gauge should bounce from one side of the gauge clear over to the other side. That shows you the O2 sensor is cycling. You should also see 1-2 cycles (full sweeps) per second. If it bounces in the middle of the gauge or cycles slowly then you should replace the sensor. It's also completely normal for the sensor to be inactive for a little while during cold start-up, the sensor needs to heat up before it's accurate.

However, erratic idle and running rich can also be cause by intake/exhaust leaks. So if the gauge shows the sensor is actually working, then I'd start checking for boost leaks and exhaust leaks between the front O2 sensor and engine.

I have a FP gauge, but how do I get an accurate reading, at idle? It usually is around like 37PSI at idle and wot I believe just over 40. I have notice sometimes my fuel pressure drops immediately after shutting off car, to just under 35.

Unhook and cap the vacuum line for the FPR. You should have 43psi at idle. The FPR is also supposed to raise fuel pressure 1:1 with boost pressure. So if boost pressure is 17psi, your fuel pressure should be 60psi.

 

[horizontalkev]

Yes my o2 sensor went bad on me and I got no cell just my wb reading rich at idle then it would start to bounce around on the gauge

Also someone let me know it I'm wrong but if you unplugged your o2 sensor when your car is running it will mess up the calibration then you will have to recalibrate it that's if your running a aftermarket WB

So you didn't have any CELs that pointed at you o2 going out? If it does mess up calibration is that easy to recalibrate?

Yes, O2 sensors become "lazy" over time. The sensor reacts to AFR changes slowly and/or incorrectly. But this is the one place a narrowband gauge is actually useful! A badly worn front O2 sensor would be obvious with a narrowband gauge tied into it. At idle, the gauge should bounce from one side of the gauge clear over to the other side. That shows you the O2 sensor is cycling. You should also see 1-2 cycles (full sweeps) per second. If it bounces in the middle of the gauge or cycles slowly then you should replace the sensor. It's also completely normal for the sensor to be inactive for a little while during cold start-up, the sensor needs to heat up before it's accurate.

However, erratic idle and running rich can also be cause by intake/exhaust leaks. So if the gauge shows the sensor is actually working, then I'd start checking for boost leaks and exhaust leaks between the front O2 sensor and engine.



Unhook and cap the vacuum line for the FPR. You should have 43psi at idle. The FPR is also supposed to raise fuel pressure 1:1 with boost pressure. So if boost pressure is 17psi, your fuel pressure should be 60psi.

I have noticed my gauge does weird things like it will be bouncing and suddenly stay at stoic and the light show stops for 5 seconds then restarts. Ill take note of the narrowbands behavior tomorrow. Should I watch it when the motor warms up?

So either my gauge is wrong or I just never noticed the gauge reading 60 PSI. Ill be sure to check that out tomorrow. Is base 43PSI okay for 6 bolt swap? And this is just to see if the base FP is within specs right, at idle?

 

[WES_393]

I have noticed my gauge does weird things like it will be bouncing and suddenly stay at stoic and the light show stops for 5 seconds then restarts. Ill take note of the narrowbands behavior tomorrow. Should I watch it when the motor warms up?

So either my gauge is wrong or I just never noticed the gauge reading 60 PSI. Ill be sure to check that out tomorrow. Is base 43PSI okay for 6 bolt swap? And this is just to see if the base FP is within specs right, at idle?

Is that strange behavior during idle, or just while cruising around? The AFR does crazy things during normal driving so just watch the gauge during idle. It wouldn't hurt to watch the gauge during warm-up, but if the sensor is really old or broken then it should be obvious right away. I'd post a screenshot of a dead O2 sensor but I don't have my tuning laptop.

Your fuel pressure is based upon your ECU. So a 6-bolt in a 2g with the stock ECU should run 43psi base pressure.

 

[Pale Horse]

The only way an O2 sensor throws a code is if the heater circuit is bad. The ECU doesn't know whether it's reading incorrectly or not - it only knows if the sensor itself is heating up through the circuit of the heater wire.

 

[horizontalkev]

I've made a video of my narrowband at idle, watch the whole video because I think it does some weird things. Car was warmed up fully during the video. Also, I checked my base fuel pressure its at 44PSI close enough right?

https://www.youtube.com/watch?v=QEUeFg1fhTg&feature=youtube_gdata_player

 

[ChiTownHussla]

U have a scan tool or DVOM? if you have a dvom, back probe the o2 sensor and find which is the output signal. This should fluctuate at idle between .02-.08. Very fast. If slow or out of range, replace sensor.

 

[Boostdriven]

I watched that video you posted and its hard to tell what it could be. Aside from a wacky narrowband reading which I wouldn't trust if my life depended on it, your car seems to be reving very easy and as rpms drop it picks up idle right away. If the car is running rich and you can see light black smoke its possible that your o2 sensor is going bad. Not being able to read actual air/fuel ratios makes it hard to determine what needs to be adjusted or replaced. You MAF-T could need some adjustment, your timing could be retarded.

If you unplug the o2 while your car is still running nothing really is going to happen to the calibration. If you leave the car running for a bit you will get a check engine light which you can reset by disconnecting your battery and turning on the light for a second to drain all residual power. If your sensor is good then ecu will go back to normal operation once you plug it in and start the car again.

If your stock o2 sensor has more then 80k miles I would replace it. You can pick one up at a local parts store for $50-$70 dollars, or you can add $100 dollars to that and buy a wide and that will take care of your narrowband. Most widebands have narrowband band output which you could wire in to your ecu. Plug the sensor in to your stock o2 bung and you're set. You can pick one up on eBay for around $160 dollars. It's a cheap investment considering the money it could cost if you damage your engine not knowing your air/fuel ratios.

 

[horizontalkev]

Thanks hussla ill look into getting one from work tomorrow.

And Im looking into buying an Innovate MTX-L wideband Im just a little confused as how to install, does it use the actual o2 sensor the ecu uses or does it have its own sensor? And what is this with metal wire? My friends GS-T doesn't have this like mine then again I have a 6 bolt swap so idk if that's why

 

[GofaST4life]

That looks like an EGT probe for an EGT gauge. EGT = Exhaust Gas Temp.

And yes, I recently changed out my O2 and my MPGs have greatly increased. I also had no Code.

 

[horizontalkev]

Yeah I figured it out, unplugged it and my ext. temp guage stopped working Thanks.

And I ordered a Denso O2 sensor from rockauto should be here early next week.

 

[Pipnorcali]

What are your egt's?

 

[ChiTownHussla]

SO DID U GET THE READINGS. ? OR JUST THROWINGP aRTS AT IT?

 

[horizontalkev]

What are your egt's?

Okay, my EGTs are approximate and while car is fully warmed up between 203-211F:
Idle: 875-897F
Cruising: 1100-1130F
WOT: 1450-1500F

Seems a little high but I don't know.

SO DID U GET THE READINGS. ? OR JUST THROWINGP aRTS AT IT?

Kindof got readings, my o2 sensor gets really wacky, volts will jump like normal then just randomly pause and act slow. Plus the o2 sensor was only 40

 

[95gstbeast]

Mine is bad, will only throw CEL lights every now and then. then they will go away. upgrading to wideband soon so im living with it until then

 

[95tsiawd0330]

I watched the video and YES YOUR O2 SENSOR IS BAD my o2 was doing the same thing I put a new one in there and no more bouncing around all you have to do is replace your 02 sensor and it will fix it

 

[blakkat]

Your wrong, a narrowband is SUPPOSED to bounce between rich an lean when the car is warmed
Up and in closed loop. The only o2 sensor on this car that should read a steady voltage is the secondary and that would be retarded to hook it up to that since it's post cat.

 

[horizontalkev]

Thanks 95tsiawd, did you have bad gas mileage before changing bad o2?

Your wrong, a narrowband is SUPPOSED to bounce between rich an lean when the car is warmed
Up and in closed loop. The only o2 sensor on this car that should read a steady voltage is the secondary and that would be retarded to hook it up to that since it's post cat.

And have you seen the video? It meant just bounce back and fourth, it will randomly pause and also sometimes disappear

 

[blakkat]

An o2 sensor is supposed to switch back and forth it may have slow response but hard to tell from a narrow band gauge. Have you noticed your cruising gas mileage has gotten really bad? Or even when your accelerating and decelerating alot?

Ecu doesn't use the o2 sensor for wide open throttle or off throttle fuel calculations. So where your noticing bad gas mileage is important. They lead in two different directions.

 

[horizontalkev]

You know Im not sure I just have very bad gas mileage.. I don't price hard so id imagine cruising speed chuggs gas