Running Without O2 Sensor

[Boxer 6]

I pulled the O2 sensor on my 87 Carrera this morning in preparation to have my "custom" exhaust system installed this coming Wednesday. I'm trying to do as much disassembling as possible to save on some labor costs The headers that I will be using have a provision for the O2 sensor so my intentions are to put in back in.

Does anyone know if there are any negative affects to driving my car without the O2 sensor. Seems to run and idle just fine without it

[aways]

The motor will not run as efficiently, with decreased performance and increased emissions...

[JMA-RUF]

With an O2 sensor, the DME forces the engine to run around the Stoich region, for best economy. Removing it makes your idle and part throttle mixture run richer, slightly improving performance at the cost of fuel economy.

[Seeeu911]

Originally posted by JMA-RUF
With an O2 sensor, the DME forces the engine to run around the Stoich region, for best economy. Removing it makes your idle and part throttle mixture run richer, slightly improving performance at the cost of fuel economy.

ahhh that description seems right for my car 87 coupe. the PO installed bursch headers and no 02 sensor. I notice the happy idle and rich smell when cold. seems "normal" when warm. mileage is not as good, but i dont care, low miles around town daily driver.. I am considering putting a bung into the header and reconnecting the sensor. Does anyone know what else needs to be done to reconnect ? She has a SW chip too.

[Boxer 6]

If I understand correctly, deleting the O2 sensor will cause the car to run richer..right? I will running European Racing headers into a VERY short muffler system. Much like the one Steve Weiner has on his website. Maybe SW can program the chip to compensate an O2 delete

[nhromyak]

IIRC - Bruce Anderson suggested the '84 - '89 cars get premature valve guide wear due to too much fuel from the factory. I wouldn't want to run without an O2 for very long...

[PatrickB]

Bursch sells a pre-muffler that has the o2 hole for the sensor. I've run mine without the o2 sensor connected, and the idle and lower rpm performance is much better. However, at the cost of about 20% drop in fuel economy....

[Seeeu911]

Originally posted by PatrickB
Bursch sells a pre-muffler that has the o2 hole for the sensor. I've run mine without the o2 sensor connected, and the idle and lower rpm performance is much better. However, at the cost of about 20% drop in fuel economy....

thanks Patrick ! I only spend about $20.00 wkly for commute gas so no biggie.. I am going to do the research on what nhromyak said re BA and valve guide wear yikes !

[Seeeu911]

boxer6 this site ? http://www.rennsportsystems.com/ which muffler were you saying ?

[stlrj]

Richer than Stoich means rich of peak EGT, higher CHT's, higher oil temps, shorter valve guide life, increased oil consumption.

Even if your 02 sensor is connected it could still be running too rich if your base mixture is set too rich, beyond the narrow range that your 02 sensor can correct.

You can Google rich of peak EGT to see the charts and how it effects air cooled cylinder head temps.

[Boxer 6]

Originally posted by Seeeu911
boxer6 this site ? http://www.rennsportsystems.com/ which muffler were you saying ?

Yes. That's Steve's site. Click on performance parts and then exhaust systems. He has a picture on his site.

During my days of building Chevrolet engines, I have "washed" rings from running REALLY rich, but I haven't heard of "washing" valve stems Are Porsche engines more prone to this?

I love this site...I'm always learning!

[stlrj]

But high cylinder head temps have been known to prematurely wear out valve guides.

Joe

[PatrickB]

and head studs...