02 Sensor...
 

How do yo know if and when it needs replacing. My car runs rich...is this bec iof the sensor? I get about 20-21 mpg (I don't ALWAYS run it hard.....is that bad? I heard these cars get about 25-28 mpg?

I have a used 02 sensor given to me that came off a good running car......anyone recomment against trying that? And if so, what difference to I look for?

I'm thinking of buying the Bosch replacement...IF I know of someone that can splice and attach with proven capability. This is definitely something I do not want to do myself since I see in FR wilks description one needs to be careful and I would want it done correctly....the first time! Any ideas??

A gas analyzer should help me, huh?

Check out www.frwilk.com

He has a section on the sensor and the best replacement.

Yeah, I saw that.....The instructions are what made me back off attempting to do it myself, but I do have some electrician friends, so I will probably buy one and let him do the splicing...

Splicing?

Cut wire.

Strip wire.

Slip connector over wire and crimp.

Install O2 sensor.

Drive car.

DUH!!!

I'm gonna do it!!!

Now, how do I know this is the problem with my poor fuel mileage? Rich running? Or should I refer to FR WIlks CO calibration set up??

Take a look in the back of the engine section in the factory manuals. There is a DME testing section. Has an x-y chart with 15 possible test ponts and 12 or 14 symptoms.

The DME thinks the engine is running lean. Where does it get this data from? AFS is hanging up or is not calibrated properly. Temp senders. One for incoming air in the AFS and engine temp.

Other causes outside the feed back loop of the DME would be a leaking injector or high fuel pressure or both.

Read through the DME testing plan in the back of the engine section.

Well, this and the repacking cv joints, axle, etc maintenance is what I am going to do next time I bring the car to my buddy's in Memphis. I am going to make a list, check it twice, and do all these little (and a few biggies) next time around.

Man, I just have so much fun when I get close to my exit on my way to work, window down and the howling 944 engine just makes my day!!

He's hooked!!!!

If the car is running rich the O2 sensor is a good place to start. You can test it with a multimeeter. Cold it should read 0 or very low voltage like .2 volts. When warm it should fluctuate between 0.45-0.7 volts. The unheated ones will last about 30,000 miles the heated ones last longer about 60,000.

Here is a quick test: Start the engine and take the car for a short drive, just long enough to get the engine up to normal temperature.

Park the car with the engine running, raise the hood, and unplug the O2 sensor. If the engine RPM does not change the sensor is most likely bad.

The reasoning behind this is with a good sensor the DME will maintain an "optimum" (at least for emissions purposes) fuel/air mixture. When an O2 sensor fails, the DME defaults to a richer fuel/air mixture to prevent detonation or ping from a lean run. There fore, if the sensor has failed, unplugging it will not change the current fuel/air mixture and the engine RPM will remain constant.

A slightly more "difficult" test involves connecting a DVM (Digital Volt Meter) to the O2 sensor output. At idle the sensor should have an output that varies, or dithers across 0.5 volts DC.

Dang right I'm hooked!!

My local mechanic has a 92 Paseo he is selling. 50k miles and runs real good.....felt lively and peppy, too.....BUT, took it for a spin and when I got to a corner I like, I said, "Forget it! I don't want it" . Not that it is a bad car, but the handling just can't stick with it, and I had no confidence and it was a tad scary, too...

I guess I'll hang onto the 944 til it breaks too bad to fix (and recover by parting out), or I win the lottery and move up!!:cool:

Thanks guys...those are nice and easy tests....I'm gonna print em and give it a shot to get an idea what my car is doing.....