O2 sensor placement

[BrownDogg]

this is a message to all the smart dudes out there, especially when it comes to exhaust. i have a 95 c1500 TBI, I installed a 96-00 crate engine so I have vortec heads. I got true dual exhaust installed but the vendor didn't install a bung plug for the sensor. Now considering I got true duals and no X or H pipe and from what I understand the ECM can only handle one O2 sensor input. How would connecting the O2 sensor to one side of the exhaust affect the performance of the engine? If I had an X pipe I'd just put in the middle of that but unfortunately that's not what I got. Any information, anyone can share will be very much appreciated! Thanks in advance!

 

[PlayingWithTBI]

How would connecting the O2 sensor to one side of the exhaust affect the performance of the engine?

As long as you don't have an unbalanced issue, it'll work fine. All the TBI trucks came with only one sensor. I'd get a heated O2 sensor though.

 

[1998_K1500_Sub]

As long as you don't have an unbalanced issue, it'll work fine. All the TBI trucks came with only one sensor. I'd get a heated O2 sensor though.

^^^ this

How ought one wire-up the heater...

- always on when IGN on, or

- only on for a short period of time?

If the latter, what determines the time period, a "delay relay" circuit? And for what period of time?

 

[PlayingWithTBI]

How ought one wire-up the heater...

- always on when IGN on, or

- only on for a short period of time?

If the latter, what determines the time period, a "delay relay" circuit? And for what period of time?

Always on with IGN on. Some people hook it up to the Fuel Pump Relay. There's other places too, it doesn't draw that much amperage, maybe ~6A

 

[Sean Buick 76]

What I do on my race car is add a bung to each side of the engine and switch it back and forth on occasion to verify both banks are happy.

 

[Komet]

X pipe would actually be a bad spot for an o2 sensor as it's too far away from the action. Put it in either bank, within 6-12" of the collector. The performance of your opposite bank will be unknown to the ecm, but barring substantial mechanical failure, it should be performing essentially identically as the monitored side anyway.

Also you're leaving performance on the table by not having a crossover. Even an H-pipe does pretty well.

 

[Road Trip]

this is a message to all the smart dudes out there, especially when it comes to exhaust. i have a 95 c1500 TBI, I installed a 96-00 crate engine so I have vortec heads. I got true dual exhaust installed but the vendor didn't install a bung plug for the sensor. Now considering I got true duals and no X or H pipe and from what I understand the ECM can only handle one O2 sensor input. How would connecting the O2 sensor to one side of the exhaust affect the performance of the engine? If I had an X pipe I'd just put in the middle of that but unfortunately that's not what I got. Any information, anyone can share will be very much appreciated! Thanks in advance!

As long as you don't have an unbalanced issue, it'll work fine. All the TBI trucks came with only one sensor. I'd get a heated O2 sensor though.

I pulled the following out the FSM, and this allows you to compare how the factory wired both
the unheated O2 vs heated (factory refers to as 'HO2S') sensors:
(Factory TBI Heated O2 sensor wiring)

The diagram even shows you which fuse they connected the HO2S heater to. Note that either
unheated or heated O2 sensor connects to the same spot on the PCM.

Hope this helps --

 

[PlayingWithTBI]

X pipe would actually be a bad spot for an o2 sensor as it's too far away from the action.

Yes, unless you have the ability to adjust the INT - Delay vs Airflow based on Gm/Sec response time in the .bin I have my WBO2 in the collector on my "Y" pipe. I had to delay response time a little to eliminate surging at idle.

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[1998_K1500_Sub]

I have my WBO2 in the collector on my "Y" pipe.

WIDEband O2?

Stupid question: What ECU are you using?

 

[PlayingWithTBI]

Stupid question: What ECU are you using?

I'm using the EBL FlashII but, you can hook the 0-5VDC signal wires to your PCM (like a 7427)'s EGR position input. You just don't run the EGR but, you have to data log and tune VE tables manually.

In the EBL it'll do it automatically with the "Learn VE" utility. You just drive around and it'll adjust the cells on the tables. It can only adjust a maximum of 12%, then you flash that .bin and go back on a ride until you get it close to where you want it. After that you can "Smooth" the tables in TunerPro RT.

Here's an example of one trip

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After corrections and some smoothing...
Low speed up to 2000 RPM

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High speed up to 6000 RPM

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Here's an example of cruising. Note: I'm running both WBO2 and NBO2 in this one (See right side of chart)

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Fun stuff