Oxygen sensor on a 1993 LT1

[norwegianvette]

Hi.

I am away at work and my FSM is at home so i have a question as i plan to replace the oxygen sensor (50 000 miles). Is it one or two sensors on the LT1 and is it an easy way to replace?

Any recommandations regarding make of sensor.

And finally is it a one or three wire connection, i see it is different sensors available.

Thanks,
Steve

 

[93Rubie]

One wire, and they are not difficult to replace. Why do you want to replace them?

 

[John Robinson]

If it isnt broke why mess with it.

 

[norwegianvette]

1. I have a slight high idle and i checked the vacuum to be fine.
2. Read somwhere that these should be replaced 50 K up.

The car has been garaged a lot, 50 K milles over 18 years and these sensors are quite inexpensive so why not be on the safe side. Have new Bosch III injectors on the way from FIC and do the oxygen sensors in the same go

Steve

 

[aklim]

O2 sensors get old and lazy after a time.

 

[norwegianvette]

30 to 50 000 miles on a non heated O2 sensor, 80 t0 100 000 miles on a heated one is kind of a shelf life. If you gas milage goes up, start with replacing the O2

Steve

 

[93Rubie]

30 to 50 000 miles on a non heated O2 sensor, 80 t0 100 000 miles on a heated one is kind of a shelf life. If you gas milage goes up, start with replacing the O2

Steve

Probably a typo on your part but...If you gas mileages goes up, start with replacing the O2." Heck, if my gas mileage gets better I leave it the heck alone.otfl

My 93 has about 53K on her and runs just fine, in fact I get 32 MPG (no joke) on trips (highway only 65mpg cruise on/a/c on). 02's may get lazy over time but unless it is lazy no need to change them. You can see if your 02 is lazy with a good scan tool my monitoring them when driving. Good one will show you a graph or at least voltage. Voltage should go back and forth usually between below 200 and above 800mv with an average in the 400 to 500mv range. Should cycle very quickly if 02 is in good shape.

IN fact a guy I know had a carburetor car he put an O2 in and hooked it up to a DVOM and used it as a tuning device. Worked pretty good. Newer cars do monitor the 02's for responsiveness and if slow to respond they throw a code. I am not sure about our OBD1 cars off hand however, they tend to have much less monitoring capabilities.

 

[BADDUCK]

O2 sensors get old and lazy after a time.

Kinda like us.

 

[dolbnyc]

I would clean out the throttle body first and run through a few tanks of gas
That is what fixed my idle issue and the car also sat for along time
Or the idle air control valve could be thei issue.

 

[Hib Halverson]

With a near-20-year old car, regardless of mileage, changing the oxygen sensors is inexpensive, preventive maintenance. The statements above about sensors becoming "lazy" or slow to respond are correct. Good sensors to use are replacement GM parts. The best O2 sensors, in my experience, are the units sold by Denso.

Another statement above suggests that a DMM and a conventional oxygen sensor can be used to "tune" a carburated engine. That's not true and anyone who tries needs to be very careful. The reason it's not a good idea is conventional oxygen sensors are "narrow-band" devices which output a high resolution signal only in narrow range of air-fuel ratios on either side of stoichiometric. At AFRs more lean than that or more rich than that, the data they output is not accurate enough to safely use in setting the air-fuel ratio at wide-open throttle which is typically 12.5-12.8:1.

This is why people who are tuning engines on dynos, be they electronically fuel-injected, late model engine, or engines with carburators use "wide-band" oxygen sensors which output a high-res signal over a wide-range of air-fuel ratios.

 

[93Rubie]

With a near-20-year old car, regardless of mileage, changing the oxygen sensors is inexpensive, preventive maintenance. The statements above about sensors becoming "lazy" or slow to respond are correct. Good sensors to use are replacement GM parts. The best O2 sensors, in my experience, are the units sold by Denso.

Another statement above suggests that a DMM and a conventional oxygen sensor can be used to "tune" a carburated engine. That's not true and anyone who tries needs to be very careful. The reason it's not a good idea is conventional oxygen sensors are "narrow-band" devices which output a high resolution signal only in narrow range of air-fuel ratios on either side of stoichiometric. At AFRs more lean than that or more rich than that, the data they output is not accurate enough to safely use in setting the air-fuel ratio at wide-open throttle which is typically 12.5-12.8:1.

This is why people who are tuning engines on dynos, be they electronically fuel-injected, late model engine, or engines with carburators use "wide-band" oxygen sensors which output a high-res signal over a wide-range of air-fuel ratios.

My bad, Hib is right, you need a WIDE band 02. I should have clarified. He was indeed using a wide band 02 to tune his carb car. My bad.

 

[Hib Halverson]

My bad, Hib is right, you need a WIDE band 02. I should have clarified. He was indeed using a wide band 02 to tune his carb car. My bad.

No...I think it's "your good" because we got to discuss an important issue. There is widespread misunderstanding about using O2 sensors for tuning at WOT. A narrow-band sensor will give you data, it just won't be very accurate, ie: it might tell you the AFR is somewhere between 12.2 and 13.2.

A wide-band O2S is far more accurate in the range were most tuners will set the AFR at wide-open-throttle.

 

[WillC4]

Well, as far as what brand. Personally i think the OEM sensors work best, seeing thats what GM specified for that vehicle. So i stay with ACDelco Sensors.

On the additional note, my Idle is slightly higher then desired as well, which it seems to stay around 1000-1400 rpm idling, as opposed to my desired 700-1000 rpm. The throttle body was recently replaced with a 52mm unit w/ airfoil and matching blades, so no grime buildup there. Now i have a pair of new sensors that i will be putting on myself this coming weekend (part of my exhaust install) I will get back to you should it at least help remedy the situation. If that doesnt work as well, then i imagine the IAC is probably getting lazy.

 

[aklim]

The throttle body was recently replaced with a 52mm unit w/ airfoil and matching blades, so no grime buildup there. Now i have a pair of new sensors that i will be putting on myself this coming weekend (part of my exhaust install) I will get back to you should it at least help remedy the situation. If that doesnt work as well, then i imagine the IAC is probably getting lazy.

Try resetting the IAC using idle counts.

 

[WillC4]

Try resetting the IAC using idle counts.

How does one do that?

 

[aklim]

How does one do that?

Get the car running in closed loop as the scanner will tell you, shut of everything but the motor and check the IAC counts. I was taught this method and it works great. It should see about 15-20 counts. If you have more counts, it means that the IAC is opening up more. Use the set screw and open up the throttle blades more buy turning the screw in. Less counts, the reverse. Each time you turn the screw, rev the engine and let it settle down and check the counts again.