Has anyone added O2 sensors to the exhaust of their Buick? I am debating adding them but I'm not exactly sure where to attach them on the down-pipes. I am not runnng headers. Thanks in advance. Brian
As close to the exhaust ports as you can get them. On a car with headers, they normally go in the collector or just after. In a car with manifolds, they go in the y-pipe as close to the manifold as possible. Factory, the General put them in the manifold, but I wouldn't suggest that, as welding cast iron is a pain. :blast:
Idea I just noticed that street hook-ups are now offered with O2 bungs welded in already. Saw it in my latest Summit Catalog. I was thinking the same thing as you....:Brow:
Sorry, just realized your not running headers. They also offer just the bungs so you can weld your own in. Just after the head pipe starts would probably be the best spot.
Yeah well, be careful of those summit ones. I ordered tham and they are NOT 3", even though that's what the web site said. I ended up ordering plain collector extensions and welding an 18mm (I forget what thread) nut on it, then drilling a hole through. Presto, instant O2 bung. Take an O2 sensor to the hardware store to find the thread size. I'd actually suggest a heated O2 if you want to actually monitor your idle mixture. Grab one from a 1990 Corvette ZR1... they're like $45 at Autozone. If you mount them at the top of the y-pipe with manifolds or shorty headers, they should stay hot enough that you won't need a heated one. It's only a full length header that dumps under the car that seems to be the problem.
Ron ,could you explain how you wired the heated O2 sensor. I understand how a basic 1 wire O2 sensor operates and how to tune with it, I was just wondering how many wires for the heating element ( One 12v and one ground?). That would make a total of 3 wires for each O2 sensor?
It's not actually wired yet, but I know HOW to wire it. It's 3 wires, one for the +12V for the heater, one for the ground for the heater, and one for the sensor. Some heated O2s are 4 wire, those have a ground for the sensor signal as well. The ZR1 is three wire. Anyhoo, I'd hook the heated element up to either a relay driven by an oil pressure switch (so they only run when the motor is actually running) or to a switched ignition (so you at least have to have the key on).
O2 sensor Can you run the ZR1 sensor with leaded racing fuel or any O2 sensor with leaded fuel? Also what gauge or device are you hooking the sensor to? Thanks
Thanks for the responses. I will mount the sensors as close to the manifolds as possible. I plan to use one on each side to drive 2 O2 sensors. I also plan on mounting a pair of AutoMeter gauges in a 4-speed console which someone butched a long time ago to mount oil pressure and ammeter gauges. The console is in great shape (if you don't count the 2 holes). It even has all three of the pot-metal pins which hold the shifter boot in place. One more question... Are the readings at the meter fairly stable or do they bounce all over the place and are they accurate enough to adjust your carb with? Brian
No, they will foul out with leaded gas just like regular O2 sensors. You can use them with unleaded race gas, but not leaded. As far as what they're hooked to, I used an autometer A/F gauge. The reading are actually fairly steady, compared to a fuel injected car. The closer you get to .450mv (stoich) the more it bounces though, because the sensor is very sensitive around there.
They don't foul with unleaded... They'll carbon up, but that can be cleaned off with brake cleaner. Eventually they'll start becoming "slow" to respond, then you replace them. I think the OE replacement intervals vary from 60k to 100k miles. With leaded? I'm not sure, but I figure you'll only get a few tanks through before they foul out.
Actually the term "sensor" is a misnomer, it's really more like a rich-lean "switch". If you've ever looked at an input-output characterisitc curve, you'll notice that it is highly nonlinear around stoich, as was mentioned earlier. If you want to accurately measure O2, get the DIY WBO2 kit. The WB (wideband, very linear) sensors are OE on Hondas and such but are still expensive ($150?). The kit is cheap, www.diy-efi.com
Maybe so, but they are still accurate enough to get idle and part throttle calibrated reasonably well. I wouldn't rely on them for WOT, other than to make sure you're definitely pretty rich. When I was tuning my V6, if I stomped it from a dead stop it went pig rich, and then slowly leaned out as the car got going faster. By the 1-2 shift it was reading off the scale lean. I found that quite useful to know. It's also really useful for calibrating the power system kick in point as well.
