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Can you explain this in more detail when you have a chance?
There's nothing more I can really explain. A vehicle handover resets the car to like new settings, erasing any learned adaptations. We mandate this when installing a new engine in a car. Learned adaptations on an engine with prior failure can cause damage to the new engine. Likewise, if sensors are bad and are replaced, the adaptations are based off readings from the bad sensors.
YMMV, but a trick an old dealer tech once showed me was to disconnect both leads of the battery and using a 12 v test lamp, to connect the positive and negative leads together (remember, battery disconnected and no trickle chargers installed, etc). This drains the residual voltage from all the vehicle systems and will in effect, carry out a vehicle handover.
There's nothing more I can really explain. A vehicle handover resets the car to like new settings, erasing any learned adaptations. We mandate this when installing a new engine in a car. Learned adaptations on an engine with prior failure can cause damage to the new engine. Likewise, if sensors are bad and are replaced, the adaptations are based off readings from the bad sensors.
YMMV, but a trick an old dealer tech once showed me was to disconnect both leads of the battery and using a 12 v test lamp, to connect the positive and negative leads together (remember, battery disconnected and no trickle chargers installed, etc). This drains the residual voltage from all the vehicle systems and will in effect, carry out a vehicle handover.
This last bit, is similar to what I suggested earlier. Is there a known minimum period of time the two leads should be in contact? Or is the test lamp there to show the job is done when it goes out?
This last bit, is similar to what I suggested earlier. Is there a known minimum period of time the two leads should be in contact? Or is the test lamp there to show the job is done when it goes out?
When I saw it done, the light lit up for not even a second. Doesn't take long to draw the voltage down, but it does it in a safe and controlled manner. I would still prefer to do it with a PIWIS or similar tester that has that functionality.
Found another cool feature in OBD Fusion that runs an O2 sensor health check. According to some things I’ve read, the O2 sensor transition time (high to low) should be 200-300ms. Anything less than a 1s won’t throw a CEL, but higher transition times are indicative of an old sensor wearing out. That can lead to distortions in LTFT. Mine are at 480ms and 600ms, so definitely due for replacement. I just need my O2 wrench to be delivered so I can do it.
Here is the OBD Fusion O2 sensor test output for anyone who is curious.
Clearing fault codes sometimes resets the fuel trims depending on if a fault code is set and DME version.
The Vehicle Handover does reset fuel trims along with a host of other things, but that is not what it was designed for. The cars are built and put in "transport mode" at the factory for the long haul across the pond and being trucked on car carriers and dealer lot. Transport mode has limit function off accessories or electrical consumers/electronic suspensions, speed limit reduced to 30mph, ect. During PDI (Pre-Delivery Inspection) when the car arrives at the dealership, or sometimes they remain in transport mode untill they are sold and the customer is ready to pick up, the car is "handed over" to the customer by running the program with PIWIS on the car that restores all comfort functions/accessories and speed limits and sets everything to "as new"..
Disconnecting the battery for 30 min will reset all learned functions, or a "hard reset" as Scott and Charles mentioned will reset them. I have seen the "hard reset" be necessary to clear some really bad learned info that would not get cleared any other way. Doing as hard reset either way is safe as long as no high powered audio system is installed with huge amps/capacitors.
Found another cool feature in OBD Fusion that runs an O2 sensor health check. According to some things I’ve read, the O2 sensor transition time (high to low) should be 200-300ms. Anything less than a 1s won’t throw a CEL, but higher transition times are indicative of an old sensor wearing out. That can lead to distortions in LTFT. Mine are at 480ms and 600ms, so definitely due for replacement. I just need my O2 wrench to be delivered so I can do it.
Here is the OBD Fusion O2 sensor test output for anyone who is curious.
Is there any trick to invoking that function? I bought OBD Fusion for another vehicle (Land Cruiser) and never thought to try it on my 996es. I just fired both of them up yesterday after a long winter's nap and the 2000 had a check engine light. I seem to remember chasing fuel trim issues last fall, but honestly forgot all about it. I also just did the battery unhooked reset Porschetech3 suggested. Would love to eliminate that light before summer driving season starts (my wife enjoys driving the 996.1 on occasion)...
No special trick. Once you are connected to the vehicle just go to Monitors on the home page and then select the O2 Sensors tab at the bottom. It takes a while to gather the data. I thought it had hit an error, but if you are patient it will come back with results in a minute.
So I tried to replace the O2 sensors today and I can’t get the *#%^ things loose. I bought a special wrench for the job. Tapped on the sensor to loosen it, applied PB Blaster. Tapped on it some more. Went for a drive to heat up the exhaust. No luck.
Any tips for getting the sensors out short of destroying them? You know I’m desperate if I’m using PB Blaster. I hate that stuff.
So I tried to replace the O2 sensors today and I can’t get the *#%^ things loose. I bought a special wrench for the job. Tapped on the sensor to loosen it, applied PB Blaster. Tapped on it some more. Went for a drive to heat up the exhaust. No luck.
Any tips for getting the sensors out short of destroying them? You know I’m desperate if I’m using PB Blaster. I hate that stuff.
Patience, the right wrench and penetrating lubricant. It is easier with the engine dropped, but doable in place. I prefer Aerokroil over PBBlaster these days, but both work, given time.
There's nothing more I can really explain. A vehicle handover resets the car to like new settings, erasing any learned adaptations. We mandate this when installing a new engine in a car. Learned adaptations on an engine with prior failure can cause damage to the new engine. Likewise, if sensors are bad and are replaced, the adaptations are based off readings from the bad sensors.
YMMV, but a trick an old dealer tech once showed me was to disconnect both leads of the battery and using a 12 v test lamp, to connect the positive and negative leads together (remember, battery disconnected and no trickle chargers installed, etc). This drains the residual voltage from all the vehicle systems and will in effect, carry out a vehicle handover.
I've applied PB Blaster 3 times over the last few days and haven't been able to get the sensors to budge. Without a lift it's really difficult to swing a hammer or get more leverage. I'm going to give-in and take it to my mechanic.
On bright side, I've driven a few more miles and I'm definitely seeing LTFT values coming back into line. So I think replacing the MAF sensor had a positive effect. I've gone from Bank 1/2 at 8.6/6.3% on the old sensor to 7.0/3.9% on the new sensor. I'd like to see both those values below 5% so I'll keep an eye on them.
Have you tried a 1/2" breaker bar with a 3' cheater pipe?
I've broken loose a lot of bolts with just that combination before.
It can generate more torque than my Snap-on MG725.(1200ft/lbs)
For O2 sensors I normally use a socket similar to this:
@TexSquirrel Your suggestion to try the crowfoot socket was a good one. Thanks! I also bought a 30" cheater pipe, but didn't have enough room under the car to use it. Luckily, with the crowfoot socket I could use my 18" breaker bar and that was enough to get the job done (at least, after 3 applications of PB blaster in the last week).
My son wants to help with the O2 sensor replacement, so I left the old ones in place after I broke them loose. I'll post an update once the new ones go in.
For now, a few more miles driven on the new MAF sensor has resulted in the LTFT getting closer to where I want it. Today it measured 6.3/3.1% (down from 8.6/6.3% before the MAF sensor replacement). Still looking for sub 5% on both banks.
04-26-2020, 12:52 PM
