O2Sensor simulator
 

I am thinking I need a simulator for all my o2 sensors becuase I use an after market ignition and hypertech programmer. What do simulators actually do? Do you think I might do better with them? I replaced all my sensors like three months ago before the installed all the upgrades and now I need new ones.

RE: O2Sensor simulator
 

You can not simulate the upstream sensors. Your truck will not run properly. The B1S1 & B2S1 sensors (in the y-pipe) need to see what is going on in their respective banks to let the PCM adjust to the fuel needs of the engine at any given time. Simulators are really only meant for emissions monitoring O2 sensors (post-cat sensors) because they do not switch, they give a some what constant mV reading that is known to mean "everything is working properly" to an OBD2 computer. I say somewhat constant because there needs to be some activity on this sensor as well, but it is only used for emissions monitoring, not for fuel delivery like the B1S1 & B2S1 sensors are.

The only reason to simulate the downstream sensor is if you replaced your catalytic converter with a high flow unit that triggers a B1S2 code or you have increased the fuel to a point at which it flakes out as well. I don't think you have done either of these things as the Hypertech really doesn't modify the fuel tables by all that much.

If anything, the ignition should promote a better burn and as a result, a more complete combustion. This should make the job of the O2 sensors and cat easier.

RE: O2Sensor simulator
 

Thanks again Kyle. I can change one though? If I do put a high flow cat then I should change all of them?

RE: O2Sensor simulator
 

Well, I think you meant P0147 and P0137

P0147 - HO2S Heater Circuit Bank 1 Sensor 3
P0137 - HO2S Circuit Low Voltage Bank 1 Sensor 2

The problem is that your truck doesn't have 4 O2 sensors as those codes would imply... I'm fairly sure that the P0137 is not correct.

It may be that B1S3 is the rear most O2 sensor. Now that I think about it (and open up my last Autotap scan) my Autotap labels this sensor as B1S3 as well. Sorry for the mis-information.

My parents '97 STS has 4 sensors. The two upstream sensors are B1S1 and B2S1. It also has a pre-cat sensor and a post-cat sensor; B1S2 and B1S3 respectively, that only monitor the input and output of the catalytic converter. B1S2 should always be the pre-cat O2 sensor and B1S3 should always be the post-cat O2 sensor, regardless of whether or not B1S2 is present.

Now onto your current problem. Did you replace your post-cat O2 sensor along with the 2 upstream sensors? Commonly only the upstream sensors (those that actually deal with the fuel delivery of the vehicle) are replaced as part of a routine maintenance when suspected of becoming lazy (not responding quick enough to changes in the air/fuel mixture).

If you kept your sensors, try throwing the original back in the rear location. Also, when you changed them, were you getting codes for them? How was your gas mileage? Did your mileage increase when you installed the new sensors?

I am sort of a pack rat when it comes to parts that I replace on my vehicles. Normally I replace things before they are actually a problem (brake pads, spark plugs, etc) and keep the old parts so that if something were to happen to the ones that are in there, I wouldn't have to immediately run to the parts store (even though I normally do) to get parts. I still have my old O2 sensor that wasn't bad from the non-AC Delco parts I had put in.

I generally put in both upstream sensors when dealing with them much the same way as I replace both headlamps when one blows. They both were in there the same length of time and both were installed at the same time so in my experiences that means that if one fails, the other isn't too long for this world.

If you either don't have the immediate cash to get both or don't mind getting under your truck twice, then one at a time isn't a problem and it really won't adversely effect anything.

For me, I can't really deal with the downtime all that well and want to get any potential problem out of the way ahead of time.

Being that your problem seems to center around your post-cat sensor, just replacing that sensor alone would be perfectly ok. But that sensor doesn't have anything to do with your poor gas mileage so your upstream sensors may be getting lazy.

RE: O2Sensor simulator
 

Seems like mo' mod, mo' problems. I had problems also with my Impala when I installed aftermarket performance sh*t. I enede take some stuff out. Runs like it should. Knock on wood (forehead.)