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Is there a specific measurement or test for the O2 sensors?
@wyovino Yes, here some info Porsche Technical Class P21 / Advanced Engine Management ...
Our 02 Sensors are the LSF Planar type that are heated and have very fast switching times....The response times from 300mv to 600mv is 60ms ...very fast ..The switching periods on a new Sensor should be every 1 second, if it gets lazy enough to slow to once every 3 seconds it will set a fault.....This is measured/times every 16 periods ...
Last edited by Porschetech3; 05-02-2024 at 09:21 PM.
It's been a few months since this discussion on oxygen sensors, so I'm curious how many people replaced their sensors and what the results were
Havent replaced mine yet which are about 7 years old. AF ratio readings were good this spring, but i have to pull out the durametric this fall and see what it reads. MaF, coils and spark plugs were just done 2 years ago. But I still have to do the Blow By test just for the heck of it. Doubt I have any problems after running 12 qts of oil on the track with a deep sump and UAOS T. Didn't experience any hiccups.
Discovered 2 large vacuum leaks which I have since repaired, but this did not affect my fuel economy or engine performance, surprisingly. I just swapped out both upstream oxygen sensors as well as the MAF a few days ago. I'll follow up on the results once I put a few more miles on it.
I have owned over a dozen 996s of all types/years. The cars seem happy to get 30mpg and above on the highway and not drop below ~17mpg in city with smoother throttle inputs. Assuming no misfire or other relevant trouble codes -I've never owned an auto but I'd go north of 26mpg easily even in modified turbos on the highway. The .2 Carrera and the GT3 are capable of 34+mpg, even above 75mph.
Again, abrupt or large throttle openings change ignition timing and fuel mixture to favor power over efficiency. Look ahead and coast earlier instead of braking, get on throttle earlier and with less wide angles when traffic starts to move etc. and you will see a pretty big improvement. An attentive driver can easily get better gas mileage than even cruise control. Some people make lots of throttle adjustments, if you minimize this, you will see a difference. This concept applies to practically all electronic ignition/fuel controlled fuel injected control system engines. I personally have not seen a fuel mileage increase from O2 sensors unless one was faulty.
To be clear, I am talking about adjusting throttle input between (arbitrarily picking some numbers) 20-25% during cruise instead of 0-45%. This is not referring to how to drive the car in a fun way. I tend to have fun on approach to and leaving the apex to be fun, and will be "sporty" with the controls for those parts. But not for adjustments I might make between 70 and 85mph. Of course, drive in a way that makes you happy. I do tons of track events and endurance races and (fuel stop/pit strategy notwithstanding) efficiency is not of concern there. Anyway, I'm just rambling now so I shall stop!
Last edited by Ahmet; 09-06-2024 at 11:59 PM.
Reason: still trying to learn English...
So, what you are telling me is, if I drive on flat roads, avoid accelerations, and drive with the AC off, I can get better fuel economy?
The way I read @Marv's comment is that I've got to get a GT3 if I want to save money on gas . At least that's what I'm going to tell my wife. We'll see how it goes -- wish me luck.
I am the Renn lister with he 996.2 that Skip referred to in post 12. My car has a 4.0 FSI Stage II+ engine. It is the m9Experience engine that I worked with Jake Raby to build. My wife and I actually went to Jake’s Skunkworks facility last July and assembled the engine with Jake coaching us. We installed the engine, ran it for 1900 miles to break it in and then drove it to Rennsport Reunion at Laguna Seca last September. After Rennsport, we drove up the coast to Seattle and then back across the northern US. We drove approx 9200 miles total and averaged 30 mpg for the trip. We drove. 400 mile + stretch across Wyoming and South Dakota at 85 mph and got 34 mpg. Photo of trip computer attached. It is a very nice engine!
Mark
wow. I have *never* broken 20mpg in my Stage II. I'm lucky to break 15mpg.
While that is some impressive fuel mileage, I am wondering if you took the time to manually figure it out (gallons at fill up vs miles traveled, blah, blah, blah). Would be interested in the difference between what the pen and paper says vs what your dash says. Again, 34 mpg in a 911 is quite impressive, but virtually unheard of. I sometimes drive like a little old lady, trying to hyper mile my car, and can't seem to get over 23/24 mpg.
The way I read @Marv's comment is that I've got to get a GT3 if I want to save money on gas . At least that's what I'm going to tell my wife. We'll see how it goes -- wish me luck.
We will be waiting with baited breath to see how that works out.
While that is some impressive fuel mileage, I am wondering if you took the time to manually figure it out (gallons at fill up vs miles traveled, blah, blah, blah). Would be interested in the difference between what the pen and paper says vs what your dash says. Again, 34 mpg in a 911 is quite impressive, but virtually unheard of. I sometimes drive like a little old lady, trying to hyper mile my car, and can't seem to get over 23/24 mpg.
Not quite pen to paper but I used to calculate at every fill up. Leftover habit from putting larger injectors when turbocharging a car (usually some BMW) and not being able to trust the "range" displayed on the trip computer. There was even a way to massage the values the on board computer saw to it would then display accurate range #s.
05-02-2024 | 09:02 PM
. At least that's what I'm going to tell my wife. We'll see how it goes -- wish me luck.
