Porsche Purge Preparation

Ah, the 911. We’ve had some good times and we’ve had some bad times. It’s kind of a love / hate relationship for me. In the end I think it’s time to move onto something else though, especially since the Vette is just about ready (post coming next week). In order to get the car ready to sell I’ve had to sort through quite a few issues but I think she’s ready to go.

The biggest issue, of course, I’ve already mentioned in a previous post. The tune was rewritten and solved pretty much every one of the aggravating issues I was grappling with (emissions, long term fuel trims, air leak codes, etc). And I think I’ve finally got almost all the other bugs worked out now too.


The TPMS system in this car periodically acted up informing me that I had a flat tire. Sometimes the warning went away, sometimes it persisted. Resetting the car’s TMPS system occasionally helped but just as often it didn’t. I had new sensors installed when the car was in Arizona so everything was troubleshot remotely.


At one point I had them mail me a new sensor and that’s when I discovered that I had aftermarket ITM sensors and not OEM. Nevertheless I installed the replacement sensor but the problems persisted. I was sent OEM sensors that turned out to the wrong ones (after they were installed). In the end I went to my local dealer (Ken Garff Porsche) and they were extremely helpful and got me the correct sensors (997 606 021 01). After having these installed all the issues have cleared up.


The Interstate battery in the car wasn’t holding a charge correctly (as indicated by my CTEK). I also noticed that the vent faced the strut brace and there was acid covering the battery pan (I don’t know if it was from this battery though). I neutralized the acid and carefully cleaned everything and then replaced the old battery with a Duralast Gold 94R-DL.  The 94R-DL has the correct oriented vent and more cold cranking amps (765 vs 700 – the more the better). I was hoping this would help overcome the crank sensor gaping issue and I think it actually has done a lot to improve it.


After changing the battery I immediately got a P0154 code which indicated that an 02 sensor had failed. Quick info: the 997 has two 02 sensors on each bank, one before the catalytic converter (sensor 1) and one after (sensor 2). As you stand behind the car bank 1 is the driver side and bank 2 is the passenger side. Anyway, looking at real time data the 02 sensor seemed to be “stuck” (02 sensors should fluctuate as their reported voltage shows lean or rich conditions). When I unplugged the sensor and plugged it back in it seemed to work for a few minutes. I picked up a set of 02 sensors from Ken Garff and scheduled an install.


As a quick aside- if you don’t have a handheld scanner of some kind I’d recommend one. I recently picked up this excellent Actron CP9575 (you can get it for less than $100) to keep permanently in the 911 and it’s come in very handy. Keep in mind if you want access to real time data (i.e. 02 sensor voltages) that not all scanners have this feature.

Anyway! Down to RaceCo I went to have the 02 sensors swapped out. I always have a good time there- great guys. Unfortunately on my trip home it became apparent that the swap hadn’t solved the problem (and it’s not easy to get to those sensors!). To add injury to insult the long term fuel trims started to max out again. As I mentioned this issue cropped up right after putting in the new battery and I began to suspect that the real problem was electrical.

I checked continuity on the new sensor and it was fine. I worked my way through all the wiring back to the DME and decided that must the problem. I unplugged everything, let it sit for a couple of minutes and then plugged it back in. I fired up the car and noticed the 02 sensor in question was cycling a lot faster. I test drove the car and everything seemed to be working correctly. Even after about sixty miles the issue seems to be completely resolved – no codes, long term fuel trims are stable and there’s no hint of anything out of whack.

Here’s the current theory: The car has an aftermarket stereo and part of the system is a capacitor. Even with the battery totally disconnected the trunk light will stay on for a bit. It’s possible the DME is still getting power even w/ the battery out and as the voltage to the DME drops (as the capacitor discharges) is starts messing with the computer. Since the computer never fully loses power any problems the lower voltage causes are retained unless the computer is physically disconnected from it’s power source. I think it’s crazy that and electrical glitch can imitate a faulty 02 sensor, but there ya go!


And I replaced the floor mats in the car with new Lloyd’s mats. I’m not sure what was in there before (pic to the left) but it didn’t fit well. There are clips that are designed to hold the mat in place but the ones on the old mat were too big and the mat would slip under the accelerator pedal. New mats, right size clips, better fit and I like the Porsche logo running across them better.

The car and I went for a drive and I busted out “Must Have Been Love” by Roxette

It must have been love but it’s over now.
It must have been good but I lost it somehow.
It must have been love but it’s over now.
From the moment we touched, ’til the time had run out.

And some “Already Gone” by Kelly Clarkson.

I want you to know
That it doesn’t matter
Where we take this road
But someone’s gotta go
And I want you to know
You couldn’t have loved me better
But I want you to move on
So I’m already gone

Looking at you makes it harder
But I know that you’ll find another

I’m ready to let  it go (of course a part of me doesn’t want to). I think I might have a buyer for the car. I sure hope he appreciates all the hassle I went through to get it ready for him.