Darien

Alright, the gas mileage is starting to drop I just passed Emissions Test here in Vegas. The car has a strong rich smell when running but no smoke.

Could this be an O2 sensor problem?

Any suggestions?

Garth S

That is often one of several reasons for running a bit rich: the sensor output voltage falls off when it becomes 'tired'. This tricks the LH into thinking 'lean' mixture - so it donates more fuel to mother nature. Beyond what the cat can clean up, you smell the rest.
If you go the replacement route, check out ebay for Bosch 3-wire sensors. I picked up NIB ones for $10-15 - then a cut & splice into the existing harness.

hlj821

My '86 did the same thing, passed smog with flying colors, but was running rich, my tech diagnosed it as an Air Mass Sensor, when I replaced it the idle and performance improved and it doesn't smell rich anymore.

Darien

hlj821, is that the sensor in the MAF?

Garth, which Bosch 3-wire do I need to look for? Not sure (NIB?)

Thanks...

hlj821

That sensor is the MAF. I bought a rebuilt one from 928 Intl. Seems to be doing a great job.

Garth S

Actually, any quality 3-wire sensor intended for one sensor prior to the cat installation will work. Bosch is reliable - and the wire colour coding will match.
NIB = new in box: beware that some flog off 'good used sensor' - generally, that is an oxymoron ....

BrianG

Is the original for the '86.5 car a 3-wire?

Shane

Yes, I bought a new one from 928Intl, since it has the grommet for the passege through the floor board. Not to metion it is plug and play.

Darien

Finally got one... Do I need to disconnect the battery to reset anything?

Garth S

It never hurts to disconnect for safety - but not necessary to reset: key off will do.
Place a block under the cat to prevent it dropping too far - or it will be hanging on the sensor wires - until they snap ...