O2 voltage just sits there and doesn't cycle at idle? With NEW o2 sensor.

[DSM-Franek]

Any reasons why my o2 voltage would just sit at .02v at idle? And not cycle up and down like it should? The o2 sensor is a BRAND NEW Denso plug and play and reads fine during logs.

Won't just sitting at .02v at idle mess with my fuel trims?

Any ideas?

Thanks!
-Frank

 

[dcg9381]

All the time, even after warm up?

 

[DSM-Franek]

All the time, even after warm up?

Yes, well after 600*F where they start to read.

Could a pre-turbo exhaust leak cause this? If it was bad enough?

Thanks!
-Frank

 

[Calan]

My O2 sensor does the same thing, although I don't know how old it is. And I definitely have AT LEAST one exhaust manifold leak (Seafoam let me know about it real quick

 

[DSM-Franek]

I have about a 2 inch crack in the top of my exhaust manifold.. God knows whats on the bottom.

Also, 1 bolt broken off in my turbine housing (manifold to turbo) and 1 broken off in turbine housing (o2 housing to turbo). Sooo i'm thinking this is the cause to my lack of 02v cycling

Thanks!
-Frank

 

[Calan]

UPDATE:

My idle surge is completely gone and rock stable at 750rpm (knock on wood). And no more bouncing around while trying to set timing, etc.

My problem seemed to be a combination of dying O2 sensor, leading to a BAD tune, and a ghetto wire installation I found at the throttle that would occasionally (and slightly) prevent the pedal from coming all the way up when my foot was off the gas.

I installed my WBO2 and replaced the ECU O2 sensor input with the simulated narrowband output from the WB. Monitored the WB and O2 trim to get the idle AFR in the ball park, set the base timing and BISS, and idle is shear tranquility now... for the time being at least

 

[DSM-Franek]

I installed my WBO2 and replaced the ECU O2 sensor input with the simulated narrowband output from the WB.

Please explain

Thank you,
-Frank

 

[Calan]

I bought a Zeitronix WBO2 system, and used it's simulated narrowband out to replace my stock O2 sensor. I posted a full write up on it here:

http://www.dsmtuners.com/forums/showthread.php?t=253491

 

[DSM-Franek]

Okkk

Just installed new evo 3 manifold and ALL new gaskets and the o2v still doesn't cycle..

I'm lost

Anyone have any ideas?

-Frank

 

[dave99gst]

you have 660's ? is it possible it isnt tuned correct?

 

[toybreaker]

If the o2 cycles while you're driving but gets lazy at idle, and bottoms out at .02v, the heater circuit may be non functional. This circuit is used to preheat the o2 at engine start-up, and keep heat in on decel when the ecu turns off the injectors.

There may also be a problem with the ground reference. There are four wires at the o2. Two are for the heater coil, one is for the signal, and one provides a reference ground for the 02 itself. When this reference is lost, the o2 voltage can so some weird stuff.

Make sure the o2 connector is clean and dry. It can get covered with oil and coolant, and eventually some can wick inside and get on the connector pins.

As a quick test, you can temporarily raise fuel pressure by removing the vacum line from your fuel pressure regulator. (plug the vacum line with a golf tee to prevent a vacum leak). This *should* bring your o2 voltage up enough to read on your logger. (Don't drive the car like this. This test is for information only)

If none of these things does anything, it may be time to get out an ohmeter and check the wiring harness integrity back to the ecu.

Good luck, and let us know how it turns out.

 

[DSM-Franek]

If the o2 cycles while you're driving but gets lazy at idle, and bottoms out at .02v, the heater circuit may be non functional. This circuit is used to preheat the o2 at engine start-up, and keep heat in on decel when the ecu turns off the injectors.

There may also be a problem with the ground reference. There are four wires at the o2. Two are for the heater coil, one is for the signal, and one provides a reference ground for the 02 itself. When this reference is lost, the o2 voltage can so some weird stuff.

Make sure the o2 connector is clean and dry. It can get covered with oil and coolant, and eventually some can wick inside and get on the connector pins.

As a quick test, you can temporarily raise fuel pressure by removing the vacum line from your fuel pressure regulator. (plug the vacum line with a golf tee to prevent a vacum leak). This *should* bring your o2 voltage up enough to read on your logger. (Don't drive the car like this. This test is for information only)

If none of these things does anything, it may be time to get out an ohmeter and check the wiring harness integrity back to the ecu.

Good luck, and let us know how it turns out.

Hey thanks alot for the suggestions,

I am going to try the fuel pressure idea today and if it does nothing I guess ill have to get an ohmeter and see if its something in the wires.

My o2v at idle is .02-.04 . If I rev the car at idle it will go to .6ish-.8ish but then right back down to .02-.04 and sit there.

Thanks again for the help,
-Frank

 

[Bmxr152]

I was having the same problem with mine for a while. What found out is that my oxygen sensor was clogged with lead from my race gas. This might not be the case with all of you but it can be clogged or somethig from running rich. You should try using some carb cleaner on the sensor. That worked, and cleaned it up very nicely. After RE-installing the Oxy sensor went back to fluxuating like normal.

 

[DSM-Franek]

I was having the same problem with mine for a while. What found out is that my oxygen sensor was clogged with lead from my race gas. This might not be the case with all of you but it can be clogged or somethig from running rich. You should try using some carb cleaner on the sensor. That worked, and cleaned it up very nicely. After RE-installing the Oxy sensor went back to fluxuating like normal.

Ok well I sealed up the whole exhaust.. And still no cycling o2v at idle.

I also tried pulling the vacuum line off my afpr but that had no effect on the o2v at all either.

I guess i'll try what bmxr152 did since it seems to have worked for him but how safe is carb cleaner for the sensor? Or should I use brake cleaner? Or electric parts cleaner?

Thanks for the help so far!
-Frank

 

[DSM-Franek]

Nevermind it says o2 sensor safe on the can!

We'll see if this works for me. I hope so.

-Frank

 

[DSM-Franek]

OK that didn't work

Anyone have any other ideas?

Thanks for the help so far!
-Frank

 

[boostngst]

If none of these things does anything, it may be time to get out an ohmeter and check the wiring harness integrity back to the ecu.

Good luck, and let us know how it turns out.

I think it's time to not take the easy road out and try toybreakers advise. Ohm out the harness.

 

[vinnybean]

What are you using to test the o2 sensor?

 

[oldman]

Any reasons why my o2 voltage would just sit at .02v at idle? And not cycle up and down like it should? The o2 sensor is a BRAND NEW Denso plug and play and reads fine during logs.

Are you saying it cycles fine on a logger but not on your blinking light show gauge?

 

[DSM-Franek]

Are you saying it cycles fine on a logger but not on your blinking light show gauge?

I don't have a blinking light show gauge...

I'm looking at the o2v using my logger. (pocketlogger + m130)

When I say it reads fine during logs I mean, WOT is a steady .94-.96 from 3k rpm-redline. This also leads me to believe the wiring is fine.

I don't know what the o2v does during part throttle/cruise but from my PO170 i'm assuming it's not cycling like it should and it's messing up my fuel trims.

Also, I was reading through some threads and found something that Nathan said, "spyderturbo007- If the O2 is bad (no voltage) the ECU will have no way to adjust FT's and will go into limp mode. If the O2 is providing consistently low voltage the ECU will try to adjust the air/fuel mixture using the FT's.....thus you positive FT's."

My o2v is low and my fuel trims are very positive so I can relate to this if that helps at all.


Thanks for the help so far, does anyone have any other ideas?
-Frank

 

[vinnybean]

yea if your using a gauge to get a reading and its giving u .02 volts then the gauge probably isn't wired correctly

 

[yokotabrat]

With everything you've checked, it sounds like your tuning may just be off. According to your profile you have a SAFC. Have you tried to adjust your low throttle settings based on what the fuel trims are saying?

 

[vinnybean]

.94-.96 volts is rich......positive FT's also means your computer is compensating (or at least trying to) and is running rich. The only thing i can think of is another bad o2 or messy wiring.....or tune...forgot to look at profile

 

[DSM-Franek]

yea if your using a gauge to get a reading and its giving u .02 volts then the gauge probably isn't wired correctly

I don't have a blinking light show gauge...

I'm looking at the o2v using my logger. (pocketlogger + m130)

-Frank

 

[DSM-Franek]

With everything you've checked, it sounds like your tuning may just be off. According to your profile you have a SAFC. Have you tried to adjust your low throttle settings based on what the fuel trims are saying?

I can't get my low settings right because my fuel trims don't move or adjust at all at idle because it just sits at .02v-.04v.

Right now i'm at 0% across on my low settings and the fuel trims are still very positive (12-17 or so)

Thanks,
-Frank