5th O2 Sensor this year!!

[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

[MNBoxster]

Hi,

It's absolutely a possibility. Winter fuels are rich in Butane and Oxygen because they are cheaper than adding other Octane boosters such as MBTE, Alkylate, and ETBE.

Because the need to meet RVP (Reid Vapor Pressure) mandates by the EPA lowers due to winter temps (allowing the use of Butane and Oxygen and still meet mandated RVPs), refiners switch to Butane and Oxygen in greater amounts (because it is cheaper to produce). This can trigger a CEL because the values lay outside the DME's pre-programmed O² Sensor values.

Since lower Octane fuels require a lesser concentration of these chemicals, they will prevent a CEL from occuring and the concequent defaulting of the DME.

Because the ambient temps are considerably lower during this season, the detonation threshold is also reduced. You may actually be OK using these fuels and the sensors will return to normal operation in the Spring. In theory the guy's correct, but in practice? Only making the switch will tell...

Happy Motoring!... Jim'99

[blue2000s]

Originally Posted by MNBoxster

Hi,

It's absolutely a possibility. Winter fuels are rich in Butane and Oxygen because they are cheaper than adding other Octane boosters such as MBTE, Alkylate, and ETBE.

Because the need to meet RVP (Reid Vapor Pressure) mandates by the EPA lowers due to winter temps (allowing the use of Butane and Oxygen and still meet mandated RVPs), refiners switch to Butane and Oxygen in greater amounts (because it is cheaper to produce). This can trigger a CEL because the values lay outside the DME's pre-programmed O² Sensor values.

Since lower Octane fuels require a lesser concentration of these chemicals, they will prevent a CEL from occuring and the concequent defaulting of the DME.

Because the ambient temps are considerably lower during this season, the detonation threshold is also reduced. You may actually be OK using these fuels and the sensors will return to normal operation in the Spring. In theory the guy's correct, but in practice? Only making the switch will tell...

Happy Motoring!... Jim'99

If it were sensative to this, it would be a widespread problem with all Porsches. It would also not be helped by switching to a lower octane fuel. I don't believe this is his problem.