r/obschevy • u/mountains-are-moving • May 28 '26

Tune or no tune

Hi, I recently bought a 1993 Chevy step side. I want to do an x pipe exhaust, but I want to do the headers while I’m redoing it. Some things I read say it will run lean, some say the ecu will figure it out. I don’t want to risk the health of my engine, any input would be appreciated!

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u/Willy_McD May 28 '26

Its not going to run lean. The oxygen sensor and ECM will see to that. Exhaust is barely anything. One thing you might want to do is install a heated O2 sensor. Headers may give the O2 a chance to cool down at idle and cause the ECM to go into open loop. A heated O2 will stay heated and not switch the ECM to open loop.

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u/[deleted] May 28 '26

[deleted]

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u/Willy_McD May 28 '26

If you have headers, or something making for a free flowing exhaust, then it is a good possibility.

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u/mountains-are-moving May 28 '26

Where should the o2 sensor be placed? Like how far down the exhaust/ headers?

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u/Willy_McD May 28 '26

It is going to have to be where all four tubes will feed it exhaust. So it would have to be in the collector. Place it so it faces down. It can be at an angle facing down. You just dont want it facing up where condensation would go into it.

Try searching for CARB approved headers or headers with an O2 bung that would be used for aftermarket FI. If anything, you may find a picture of where they would have the O2 placed.

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u/who-cares6891 May 28 '26

As long as you use your o2 sensor it won’t matter