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Old 10-07-2025, 11:45 PM   #1
GTSideSwipe
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89 V2500 No TBI O2 sensor?

Hi everyone, I just recently got my Suburban 4x4 with a 350 TBI and is running rich at idle and I cannot for the world of me find a o2 sensor connecter anywhere and there is no o2 sensor on the exhaust and where there would be one, it is just plugged with a pipe plug and looks original or has been there for yearsÂ…. So my question is did these come without any o2 sensor? And if they did, could one of you possibly post a picture of where the connector isÂ… thanks
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Old 10-08-2025, 09:36 AM   #2
THI
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Re: 89 V2500 No TBI O2 sensor?

They came with an O2 sensor on the driver side exhaust manifold facing the rear on the outlet.
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Old 10-08-2025, 03:05 PM   #3
GTSideSwipe
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Re: 89 V2500 No TBI O2 sensor?

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They came with an O2 sensor on the driver side exhaust manifold facing the rear on the outlet.
I know and I can’t find the connector anywhere and it’s plugged with a pipe plug and looks like it’s been there from the factory. That’s why I’m wondering if someone could post a picture.
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Old 10-08-2025, 07:20 PM   #4
GTSideSwipe
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Re: 89 V2500 No TBI O2 sensor?

Alright, so I ended up lifting it up on my lunch and found it next to the transmission right after where the 2 pipes join together. Had a extension harness on it to get there so it reads both banks.Thing was completely frozen and got it out with a mix of crows feet, air hammer and wrenches but just happy I got it out and got a new one in.
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Old 10-14-2025, 10:02 AM   #5
RaTcheTmasTer
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Re: 89 V2500 No TBI O2 sensor?

so it fixed your problem?
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Old 10-14-2025, 01:31 PM   #6
GTSideSwipe
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Re: 89 V2500 No TBI O2 sensor?

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so it fixed your problem?
Hey, sorry about not updating. It seemed to help a bit but I was messing with the throttle body and found the bushings in the throttle shaft to be really worn. I’m debating rebut or finding one from a pick n pull.

But yeah it seemed to help. I’m gonna do a complete tune up on it next soon.
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Old 10-24-2025, 11:30 AM   #7
THI
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Re: 89 V2500 No TBI O2 sensor?

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Originally Posted by GTSideSwipe View Post
Hey, sorry about not updating. It seemed to help a bit but I was messing with the throttle body and found the bushings in the throttle shaft to be really worn. I’m debating rebut or finding one from a pick n pull.

But yeah it seemed to help. I’m gonna do a complete tune up on it next soon.
They all leak at the throttle shaft over time, rebuild kits for the throttle body are inexpensive and the process to bush the casting is the same as the quadrajets only you have one shaft to bush. It is also easy to convert the pressure regulator spring to adjustable when rebuilding the unit.
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Old 11-18-2025, 09:35 PM   #8
chris989
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Re: 89 V2500 No TBI O2 sensor?

Hello,

I am no pro but help a few guys here and there. I have an 89 v2500 also. The location of your O2 is too far back. get it closer to the engine and install a 3 wire.

Without a heated o2 you will never get into closed loop and will run in the default table.

If you are going headers, put it in the collector. If you can get i t back in the manifold you might not need a heated sensor.

If you are not in closed loop, nothing will work well.

Chris
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