o2 sensor issue at idle

ok so i am having some new issues with my 1995 non sc riviera. it seems that when my car is idleing for more than 5 or 10 mins i will get a service engine code saying O2 sensor low circuite. however i can be driveing either around town or on the highway for any amout of time and get no codes at all? any help or ideas as to what can be causeing this. the first thing i tried was to replace O2 sensor figureing that may of been the problym but had no luck.

What is the exact code?
Probably have to check and test all related electrical connections per the FSM.
Also look for any chafed or burned wires. Sometimes you get lucky and find the problem in an easy to repair area.

Generally it's correct, your O2 is getting "lazy". If that's not it, do you have any exhaust leaks, even tiny ones?

I got a bad Delphi sensor new out of the box, when i did my headers recently, but it tripped a code for "insufficient switching".
After looking at the signal on a lab scope, it was very lazy and erratic at lower RPM's and good at higher RPM's.
Had to get another Delphi unit.
It is not uncommon to get bad ones new. They can be mishandled / dropped during shipping and mess them up.

thank ill get the exact code tommorow before i head to work, i dont know if it may be related but the only other issue i am haveing with this car is that the idle seems to be a little rough at times, but other times its perfect. this seems to be most noticeable when im stoped at a light and the car is in drive.

What brand is your replacement O2? I have heard of a lot of 'lazy' issues with many aftermarket O2 sensors, and that a Delco O2 sensor solved the problem.

thanks i will checkthat out today when i get home from work, can this be affecting the roughness in my idle. also when you say "lazy" what does that mean?

http://www.google.com/search?client=safari&rls=en-us&q=lazy+O2+sensor&ie=UTF-8&oe=UTF-8

It means the O2 sensor is not creating enough cross-counts for the exhaust pulses.

can that be giveing me a rough idle?

Yes

is there any way to test the o2 sensor to see if it is being "lazy"

With a computer you could observe the cross-counts. Not an easy thing to do...

Check for big vacuum leaks, spray around the throttle body and intake manifold with some carb cleaner and see if you affect the way the engine runs. Make sure all vacuum lines are connected properly. This could be causing a lean condition that's being misinterpreted by the computer.

thanks again, i have a computer to read the live data, what would i be looking for in the cross-counts that would indicate a problym with the sensor

Not enough of them. I don't know what that value is, but there should be a cross-count for each exhaust pulse, it's looking for a certain number per second as a minimum. I'm afraid I can't be any more technical than that, as I'm not sure what the values are supposed to be, or where to look in the computer for them, or if you can even see that value in the computer!

Anyone know if AllData or one of the other online tech subscriptions has this info?

so i replaced the o2 sensor finially btut i am still haveing the same problym the code p0131 o2 signal to low keeps comeing back when my car is at idle does any one have any other suggestions,

What brand O2 sensor did you use?

edit: Unlikely but it could mean you have bad injectors causing a lean condition, or a MAF problem. Have you ever cleaned the MAF sensor?

DTC P0131 = HO2S Circuit Low Voltage Sensor #1

(The following is from the FSM)

Check for the following conditions;
- Heated oxygen sensor wiring. The sensor pigtail may be routed incorrectly and contacting the exhaust system.
- Poor PCM to engine block grounds. refer to wiring diagram.
- Fuel Pressure. The system will go lean if pressure is too low. The PCM can compensate for some decrease. However, if fuel pressure is too low a DTC P0131 may be set. Refer to fuel pressure test procedure.
- Fuel Injector(s) Refer to Fuel Inj Coil Test
- Vacuum leaks. Check for;
disconnected or damaged vacuum hoses.
incorrectly installed or malfunctioning crancase ventilation valve.
Vacuum leaks at the throttle body, EGR valve, and intake manifold mounting surfaces.
- Exhaust leaks
- Throttle body inlet screen, check for damage.
- MAF sensor. Disconnect MAF sensor. If the lean condition is corrected replace MAF sensor
- Fuel contamination

There is much more in the FSM regarding this code, too much to type here. There is a lengthy paragraph on measuring voltages with a 10 megohm digital voltmeter. Need to be able to read in the mV range.
Suggest getting a copy of the FSM, will help you in the long run diagnose and troubleshoot not only this problem but any future problems.
HTH

thanks alot for all the help, had my dad take a look at it and it turned out to be that the cause was my idle being to low .

Idle too low... so was it the IAC?

Idle should be controlled automatically, so unless you had a bad idle air control motor, that doesn't make sense to me.

idk theres a little screw in the back of the throttle body that increased the tension on the the throttle cables, im not an expert or nething but i turned the screw a little my idle increased the roughness seemed to level out.

So... i have this dumb code for my O2 sensor DTC P0131 = HO2S Circuit Low Voltage Sensor #1...

I replaced my O2.. and it had the same issue of rough idle.. and when im going down a hill the rpms surge from 200rpms to about 1100 rpms.. so i got another new one.. SAME PROblem... and than i went ahead and i unplugged my o2 all together so that my car would run normal.. so right now i am running open loop.

Its fixed... thanks for the input.....

98riviera98 wrote:

Its fixed... thanks for the input.....

Your Welcome from all of us. I think.!!!

It's very difficult to offer advise on problems when your running # 79 injectors and corn liquor.

So, what did you find to be the problem and the fix.?

EGR problem?

98riviera98 wrote:

Its fixed... thanks for the input.....

8 minutes after the original question? You seriously expected help inside 8 minutes at 3 in the morning?

So what was the problem? Burnt wire?

Deek,
I think it was 24 hrs 8mins.
But still, @ 02:40 not too many people looking at the board.