TEN DOLLAR

Gentlemen,

I've had a persistent uneven idle for 18 months now. The car would hunt up and down 100 rpm once the car was warm. So after replacing every other electrical part to no avail, I decided to disconnect the o2 sensor to see if it was causing the problem. The idle is now almost perfect and the car runs great in all other ways.

So my question is, why do I need to replace the sensor if the car runs fine? What does the sensor do, if it runs ok with out it?

Cheers

TD

Indycam

The brain of you car needs that O2 sensor to do a better job of keeping the fuel air ratio "right" .
You and your car will do better with the O2 sensor working .
If the brain runs the motor rich , thats your gas money being blown out the tail pipe .
Drive it long enough without the O2 sensor , the cost of the wasted gas might cover the cost of the replacement cost of the O2 sensor . If unburn gas gets into the cat , the cats going to get hoter , maybe cutting its life down .

Gus

If unburn gas gets into the cat , the cats going to get hoter , maybe cutting its life down .
Solution is then to remove the CAT and go to a bypass - even if you replace the O2 -
Benefir - better sound a few more ponies - Have you cleaned the idle speed control (positioner)

springer3

Please don't do this. We need clean air, and the catylitic converter does a great job at essentially no cost in fuel or power loss. Replace the O2 sensor, keep the cat!

TEN DOLLAR

Thanks guys for your replies.

I have not cleaned the Idle Speed Control (positioner). What is it and where is it located? I assume you don't mean the ISV valve, which I have cleaned.

I think I'd only remove the CAT if I end up trashing it removing the sensor after 18 years of rust!

Cheers
TD.

Gus

ISV and ISC (positioner) are the same - if you have cleaned and still had trouble then it was probably your O2 -

HalV

Is there a potential that the car could run too lean if the ECU doesn't have feedback from an O2 sensor?

Indycam

Gus
He said that he had no problem with the O2 sensor unpluged .
If it was an ISV needing to be cleaned , why would it be fine at idle now ?

Hal5
Because lean is so very bad for an aircooled , I think the afr goes rich .
I think the factory would / has set up the computer to send it rich if the O2 sensor is gone .
But without doing tests it would be hard to say 100% one way or the other .

Indycam

"I think I'd only remove the CAT if I end up trashing it removing the sensor after 18 years of rust! "
If the O2 bung is trash , you can buy a new bung and weld it on .

http://www.jegs.com/webapp/wcs/store...FSJIagod51q79A

Indycam

One more thing ,
there are more than one type of O2 sensors for this car .
Some are better than others , if you go for a new O2 sensor
it might be wise to get one of the good ones .

Indycam

One more another thing ,
where in the UK are you ?

Indycam

The one sold by porsche is known to be a good one .
If you order one from sunset and have it shipped to where you are going to be ?

Indycam

I see you , wave .

http://maps.google.com/maps?sourceid...=1&sa=N&tab=wl

Indycam

$ 144.85 from sunset
145.00 USD = 97.2852 GBP

shipping aprox $10 to the east coast .

Indycam

$ 263.21 at the porsche dealer in boston
http://chambers.porschedealer.com/index.php