Just a reminder to anyone who decides to replace their factory manifolds with long tubes and has a factory unheated (one wire) sensor. There is a good chance (almost positive) that you will need to replace your unheated sensor with a heated sensor. The reason for this is on most installs the O2 sensor is moved to the collector from the original location farther up in the stock manifold. This means the O2 sensor does not heat up enough to work and the computer won't use it. This will make your car run in open loop all the time (off factory tables) without using the actual O2 sensor values (closed loop). A heated O2 sensor will correct this.

I installed a heated O2 sensor on mine a few years back and it made a huge difference.

The reason I bring this up is I was helping Mike (HDFire) the other day and he mentioned his car had a lack of power after his header and exhaust install. Upon scanning it, I saw it wasn't going in to closed loop when the motor was heated up. He recently installed the heated O2 as I suggested and now states the car runs completely different.

I posted pictures of my install when I did it, you will be able to find it with the search function.

Matthew

This is excellent advice! The O2 sensor is your main tool in tuning and without it, oopsie.

I couldn't fine the previous post. I think I need to do this on my '92.

http://www.corvetteguruforum.com/modu ... e=&topic_id=11082&forum=1

The only other thing I would say is use a relay as the O2 sensor does draw power. I originally used the fuel pump enable wire (hot only with ign on) but it has the potential to draw too much power and throw a code. I had a fuel pump code and my car stalled after some back to back WOT testing runs. So instead, wire a relay and use that as the trigger wire with power directly from the battery.

Matthew

I am installing new exhaust does a heat sensor need to go back on?

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Definately

And If I wanted to go with the heated sensor where could I get one

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Any parts store or rockauto. There is a part number in the other thread, but basically an universal three wire sensor.

Why don't you do the field service mode check first to see if the car is going into closed loop with the stock O2 sensor. Mine always did, with tPIS headers, after about 5 minutes of driving.

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Is there an easy option for "key on power" under the hood. I don't want to remove my dash panel again. I have the relay and sensors wired in.

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All the relays should be key-on powered (hot all the time) because they are activated by grounding them (not applying power to them). So it would depend a bit on fuse & wire size, I don't know the amperahe of the O2's. But it should work off one of those hot wires.

I've seen people on forums use the fuel pump relay or wiper relay. The wiper relay wiring was really thin, so I don't recommend that. I used the fuel pump and gave direct power to the O2 from that. That is NOT the right way to do it as I found out. Use the fuel pump relay for power on to a separate relay and feed the power from the battery.