Erratic Idle O2h:on, O2-1:0.00v

[mle808]

Hi,

I'm having a very bad idle at the moment, been happening for 2 days now.

Normally revs would sit at 700rmp ish.

Injector Duty at 1.0%

IgnTm at 15

Now when the idle problems started, revs would start at 1500rmp, Injector Duty at 2.2% and Igntm would be at about 22.

O2H is off, O2-1 is about 3.88V.

Then after a mintue or two the O2-1 reading would gradually fall to 0.00V and the O2H check turns ON (black).

I noticed when the 02-1 gets to 0, revs will then suddenly drop to about 1000rmp, Injector Duty to 0% and Igntm around 15-17.

This will just continue to cycle, taking about 2 seconds for the full cycle. So its extremely annoying and embarrassing, esp in peak hour traffic. The only thing that I can do to stop the rev hunting is to apply throttle keeping the revs above 1500rpm.

Also, after turning off the car, I go into the check sensor screen and I notice the O2-1 reading gradually increases until its back to the 3-4V range. If I start the engine again and let it idle, the idle is still high and the O2-1 reading begins to fall, hits 0.00v then idle hunt begins again.

It has happened in the past but usually goes away within a day, so I've never had the chance to take it back to the tuner to have a look. I've only noticed these figures today after driving around in the Check sensor screen. In the past I've tried cleaning the ACC valve, air flow meter, check for vacuum leaks, check sensor plugs around the throttle body etc, but guess it didn't help.

Has anyone had this problem or know what I should be checking next?

Tried searching the forums but its either fuel economy related issues or I just didn't understand some of the info.

Any further info/help/ideas would be greaaaatly appreciated.

Thank you....

[Benzino33]

Hi,

I'm having a very bad idle at the moment, been happening for 2 days now.

Normally revs would sit at 700rmp ish.

Injector Duty at 1.0%

IgnTm at 15

Now when the idle problems started, revs would start at 1500rmp, Injector Duty at 2.2% and Igntm would be at about 22.

O2H is off, O2-1 is about 3.88V.

Then after a mintue or two the O2-1 reading would gradually fall to 0.00V and the O2H check turns ON (black).

I noticed when the 02-1 gets to 0, revs will then suddenly drop to about 1000rmp, Injector Duty to 0% and Igntm around 15-17.

This will just continue to cycle, taking about 2 seconds for the full cycle. So its extremely annoying and embarrassing, esp in peak hour traffic. The only thing that I can do to stop the rev hunting is to apply throttle keeping the revs above 1500rpm.

Also, after turning off the car, I go into the check sensor screen and I notice the O2-1 reading gradually increases until its back to the 3-4V range. If I start the engine again and let it idle, the idle is still high and the O2-1 reading begins to fall, hits 0.00v then idle hunt begins again.

It has happened in the past but usually goes away within a day, so I've never had the chance to take it back to the tuner to have a look. I've only noticed these figures today after driving around in the Check sensor screen. In the past I've tried cleaning the ACC valve, air flow meter, check for vacuum leaks, check sensor plugs around the throttle body etc, but guess it didn't help.

Has anyone had this problem or know what I should be checking next?

Tried searching the forums but its either fuel economy related issues or I just didn't understand some of the info.

Any further info/help/ideas would be greaaaatly appreciated.

Thank you....

Yepp same problem, sometimes my car idles at almost 2 grand and wont go down. what i found is that wen im driving and i turn the car off, let the boost guage come back to zero,turn it back on (in neutral).. it runs fine after .. but i did an ecu reset the other day and seemed to fix most of wat was wrong with my idle. other than that hoo hah, i'd check the tps is positioned right and you iac valve it in working order.

hope this helps,,

Ben

Edited May 22, 2009 by Benzino33

[R31Nismoid]

so turn the O2's off, problem solved

[mle808]

so turn the O2's off, problem solved

Not sure if I did it correctly, but I went to the function select screen and turned off O2 Feedback.

Nothing changes.....

[paulr33]

when did the problem start?

has it always been like that?

try unplugging the 02 sensor (its on the exhaust dump pipe) - ive never seen a narrow band 02 sensor go past 1v, thats because, they dont

so your sensor is completely shagged or you have wiring fault

im surprised the engine check light isnt coming on

02-1 should be in the range 0.00v to 1.00v as its only a narrow sensor - 3v is off the planet!

unplug 02 sensor and see if that works

if not - check basics and maybe perform self idle adjustment (youll loose the tune, so get someone datalogit to copy it first)

[mle808]

when did the problem start?

has it always been like that?

try unplugging the 02 sensor (its on the exhaust dump pipe) - ive never seen a narrow band 02 sensor go past 1v, thats because, they dont

so your sensor is completely shagged or you have wiring fault

im surprised the engine check light isnt coming on

02-1 should be in the range 0.00v to 1.00v as its only a narrow sensor - 3v is off the planet!

unplug 02 sensor and see if that works

if not - check basics and maybe perform self idle adjustment (youll loose the tune, so get someone datalogit to copy it first)

Hi

The problem seems to come and go when it feel like it. Its been over 12 months since the last time I've had the problem.

After my previous post I took the car out...and bloody hell...the problem is gone again.

I did take note of the sensor check screen though. It seems when its back to normal:

02-1 voltage starts at 3.88v then gradually drops to 0.00 after 10-15 minutes, but the 02H is constantly ON right from the very beginning. Unlike when during the idle problems existed; 02H is OFF until 02-1 gets to 0.00 then idle starts hunting.

Yeah I've read on the forums that 02-1 should be 0.00-1.00.

It might be completely shagged as i've never changed it. But then again when I got it tuned, it wasn;t lean and I don't seem to have that bad of fuel economy. 400-450km per tank.

Next time I get the problem I'll try unplugging the 02 sensor and see how that goes.

But with the problems coming and going so quickly its a little hard to justify the reset and idle adjustment...

Can you tell me what the 02H is? I've read on your guide its the 02 Heater Sensor Setter, just not sure what it does. Perhaps I can try and check if there is a wiring fault or short somewhere.

Thanks for your help paulr33.

[paulr33]

yeah unplug the 02 sensor for a few days, it wont do any harm, just economy wont be that great

ive never seen a narrowband go to 3v, i'd say something is really wrong

02H is 02 heater control, when the car starts, the 02 sensor must be hot (temperature wise)

so it has to heat itself up before it can tell the ECU anything useful

so its normal for 02H to be on and remain on for some time

the 02 sensor is a $100 part so its worth changing - unplug first to confirm

[mle808]

The idle problems have gone now, but as stated in the 02 sensor thread, the sensor should have been changed a long time ago.

What should I be looking for after I unplug it? Because idle is back to normal now.

Do you mean, if its rooted and I unplug the sensor nothing would be changed?

Is it weird to you that the 02H is constantly ON and does not turn off?