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02 circuit - can it be eliminated?


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8 replies to this topic

#1 thealleyboy

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Posted 17 September 2006 - 09:19 AM

The vehicle is an 85 GL carbed A/T.

I want to install a new different y-pipe, as part of an exhaust system overhaul. The new "y" does not have a bung for the 02 sensor, so I will not be able to reinstall the 02 sensor.

Does anyone know of a way to bypass the 02 or "trick" the ECU in a way that will still give the car optimal performance?

thanks, John

#2 NorthWet

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Posted 17 September 2006 - 12:29 PM

No good way to trick the ECU. (Could supply a constant 0.7v? to the EGO wire.) Assuming the ECU and carb are similar to EA81 versions, all the ECU will do is control duty-cycle solenoids that control bleed air into the carburetor mixture passages. Net effect is that without ECU direction your mixture will be a little richer. Do you have emissions testing to worry about?

#3 thealleyboy

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Posted 17 September 2006 - 01:43 PM

No, no E-checks in Central OH {yet}...

I guess the question is how rich?

If it's gonna affect performance and mileage too adversely, I guess I'll have to find the correct "y".

BTW, the "AIR" system is no longer part of the mix, if that makes any difference.

thanks, John

#4 GeneralDisorder

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Posted 17 September 2006 - 03:32 PM

Just install a Weber.

Without the 02, mileage will be very poor. About 15 MPG.

GD

#5 thealleyboy

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Posted 17 September 2006 - 04:30 PM

Just install a Weber.

Without the 02, mileage will be very poor. About 15 MPG.

GD


Hate to waste a Webb on such a lowly rig...this is just a daily driver - nothing special...

I don't remember which car the "non-o2" Y pipe came from, but I'm thinking it must have been from an 86 or 87 carbed vehicle. Wierd that some models {apparently} had the 02, and some didn't.

John

#6 GeneralDisorder

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Posted 17 September 2006 - 04:49 PM

The 02 is found on the 2WD's, and the CA emissions 4WD's. The "49 states" vehicles did not have them.

You can either put a non-feedback Hitachi on it, or you can put on another carb, but without the 02, the system will not run correctly at all. It will be very rich.

You could add the 02 to this "new" y-pipe if you have access to a welder. Just find the right sized nut, drill a hole and weld the nut over it.

GD

#7 john in KY

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Posted 17 September 2006 - 07:43 PM

Why not just remove the O2 bung from the original pipe, drill a hole in the new pipe and then weld the bung onto the new pipe. I've done this several times.

#8 beataru

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Posted 17 September 2006 - 08:31 PM

yeah ive heard that the webers for it are sweet... and they eliminate all of those annoying and confusing Vaccum lines that go EVERYWARE!

#9 GeneralDisorder

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Posted 18 September 2006 - 02:19 AM

yeah ive heard that the webers for it are sweet... and they eliminate all of those annoying and confusing Vaccum lines that go EVERYWARE!


Frankly, you can eliminate almost all of those vac hoses while still retaining the original Hitachi. The feedback system does require a few more, but even that can be simplified if you just understand how things work. And if you use a non-feedback carb, all you need is the manifold vacuum to the heater controls in the cabin, the vacuum advance for the distributor, the EGR (unless you eliminate that too, which can be done), and the choke pull-off. The other lines are not required, but it does take some knowledge to remove them, or reroute them.

GD




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