5th O2 Sensor this year!!

[xclusivecar]

Replaced all 4 O2 sensors over the last year...then the MAF...then 1 Cat...and now ANOTHER O2 sensor! After questioning the Porsche mechanic as to why this is happening, I am told that Porsche has had a bunch of problems in the winter with the reformulated fuels damaging the O2 sensors. He also states that Mercedes is also having similiar issues with its AMG engines.

Now, this somewhat makes sense since I DID NOT have any troubles this past summer. All troubles have been during the past 2 winters.

He summarizes by telling me I need to OCCASIONALLY gas up using 87 or 89 octane. This would somehow force the engine to "clean" itself and all emission components downstream. Then go back to 92-93 octane for several tanks and continue this throughout the winter and until summer blend gas is back.

Does this make sense? or...am I being led?


The car is a 2000S

[blue2000s]

It's BS. Go to a different mechanic who can actually fix your problem.

[Darkhamr]

I'm not sure what specifically could cause the O2 failures, but perhaps sticking with a 'Top Tier' supplier might help.

http://www.toptiergas.com/retailers.html

[Cloudsurfer]

I can't possibly see what your mechanic claims 87 octane would do for your motor, aside from cause problems. While there are differences in winter blended fuels (in those parts of the country where it does get cold), ad that could hypothetically cause issues with certain motors (never heard of this directly, but it could be plausible), running a lower octane fuel to "clean" an engine is ridiculous. All that would do is force the engine to run greatly reduced timing to control knock, limiting performance, and making the DME re-learn how to operate on the proper fuel once its given it, and may or may not cause serious damage in the interim.

What may contribute to your 02 sensor issues during the winter is the longer time it takes things to heat up from a cold start, which would cause increased deposits to form on the sensors.

I'd also consider looking for a new mechanic.

Patrick

[blue2000s]

Originally Posted by bmwm750

I can't possibly see what your mechanic claims 87 octane would do for your motor, aside from cause problems. While there are differences in winter blended fuels (in those parts of the country where it does get cold), ad that could hypothetically cause issues with certain motors (never heard of this directly, but it could be plausible), running a lower octane fuel to "clean" an engine is ridiculous. All that would do is force the engine to run greatly reduced timing to control knock, limiting performance, and making the DME re-learn how to operate on the proper fuel once its given it, and may or may not cause serious damage in the interim.

What may contribute to your 02 sensor issues during the winter is the longer time it takes things to heat up from a cold start, which would cause increased deposits to form on the sensors.

I'd also consider looking for a new mechanic.

Patrick

The sensors are self-heating. They wouldn't have this problem.

Eclusivecar, what Porsche dealership is telling you this in the Chicago area?

[Cloudsurfer]

I am aware the sensors are self heating, but correct me if I'm wrong, unless you instert the key and turn to on and give it 15 sec to heat the sensors, you are still firing the motor with them cold. Granted, this may be splitting hairs and I was simply trying to explain a point likely unrelated to his problem, but worth noting nonetheless.

Patrick

[porsche986spyder]

Why not just use a good fuel injector cleaner once in a whie?

[blue2000s]

Originally Posted by porsche986spyder

Why not just use a good fuel injector cleaner once in a whie?

His problem isn't fuel or clogged injectors, it's a mechanic who's replacing things that aren't broken and either not willing or not able to really fix the problem.

[SigmaPi]

If that is true about the O2 sensors being sensitive to fuel mixtures, why has it not affected my Lexus or 4Runner in the same manner? Porsche is obviously a superior product right?

[MNBoxster]

Originally Posted by SigmaPi

If that is true about the O2 sensors being sensitive to fuel mixtures, why has it not affected my Lexus or 4Runner in the same manner? Porsche is obviously a superior product right?

Hi,

Not at all. It could be construed that Porsche is inferior. It's not the O² Sensors, but the software limits of the DME. It does not have any Maps for the readings the sensor is sending it - the values lie outside the defined operating parameters.

Your other cars may well be affected, just not to the same degree. The ECU has an adequate Map to cope with the circumstances and so doesn't foul the O² sensor or send a code...

Happy Motoring!... Jim'99