2007 base 2.7 with Tiptronic with 75,500 miles!
After driving on a commute for thirty minutes and taking off from a traffic light my car will shift at around 2000 rpms till it gets to 4-5 gear all good!
So around 25-35 mph and 1500 -2000 rpm either 4th or 5th gear, typical city commute on the highway, the car with buck like a mother f%^r. I have to let off the gas and repress the pedal once i have some distance from someone in front of me and move along to avoid the strange zone. Get this NO CODES EVER nothing pending either!!!
So, I begin to record graphs with my scanner. Two things will show up when this occurs. First the MAF graph was going up and down like crazy. Second the TPS% graph was also go up and down during my diagnosis. Pull the car over and turn engine off and leave key on to see if I have any throttle or pedal issues. The pedal graph is smooth as butter no drops, jumps or hiccups. I must have performed this test a dozen times just to make sure it could be the pedal. I even took the pedal apart down to the circuits and cleaned them to be sure. That did not work!!!
Now reading the MAF sensor I got bad readings and even cleaned the sensor. That did not work.
Calc Load is 98.5% to 99.2% on WOT! While I can say the mass air flow sensor is working just a little suspect on the specific range that it might not be operating/reading correctly.
So, I decided to throw money on a new Aftermarket Bosch MAF. My only reservation with this was that is an aftermarket part. It helped a bit and I thought finally this could be the cure!! Still this did not work.
Now this is getting stupid, the only thing I could think of was something like a vacuum leak could be an issue. Of course the simple things like a new air filter and spraying throttle body cleaner was utilized. Nothing works or changed. Of course my readings from my scan tool shows short-term and long-term fuel trims are pretty much zero, meaning I have no leaks!! I can strongly attest that I don't have a vacuum leak. O2 sensors are reading and giving no indication of any faults.
I decide since I have owned my car this many years and never changed the AOS hmm maybe this is it. Now the shitty feeling of throwing parts is beginning to really tick me off. I am a strong proponent of proper diagnosis and I promise you the battery is even new as well and fully charged. I started with the basics!!! So here I go replace the AOS with the theory that maybe the diaphragm inside the AOS could cause variable shifts in the vacuum pressure and thus giving me the strange wave form of the MAF reading and bucking.....(make sense right). I did buy a Genuine Porsche AOS right from the dealer showroom floor. With all the excitement I thought this has to cure it........NOPE!
This weekend I will be taking the whole throttle body and plenum out to change the starter for another issue related to a loud chirp sound only when starting. I was thinking of doing the IPD plenum but just a bit ticked off throwing money on this issue. Costco has a big screen on sale for 600 bucks!! What i do plan on doing is cleaning the original plenum, check the hoses and making sure the actuator under the plenum is not binding or seal it off all together. From a logical standpoint I have no vacuum leaks that are showing up based on my readings.
Any thoughts on this is welcomed !
I think you are on the right track by cleaning the throttle body. Good luck. Look in the articles here on how to change your AOS.
Audi tiptronics can act like this when the torque converter is going out. Not sure about
Porsche
units, but it sounds like a transmission issue to me if it only happens in 4 and 5 (not gears 1-3). Have you checked the trans fluid yet?
I would have said bad gas, but I assume you have run a few tanks through it already. So good luck!
Thank you for your reply Dr Acula!! I have checked the fluid level and quality also did a fluid change 15,000 miles ago with Redline Synthetic fluid. From a level and fluid perspective all looks beautiful. I have experienced a this few times in second and third gear but i did the replace the MAF sensor (aftermarket) and the AOS new(genuine), right now I am getting her to do it in 4-5gear and at 1500 - 2000 rpm as I am in traffic.
Thank you so much for your reply Rick H. LOL yes, I have mixed all different brands as well.
Thank you Rob VN. After a sleepless night, I am thinking more and more about the throttle body. This weekend I have to replace the starter so I am going to clean it but, this will be my one last "throw parts at it" before my patients runs out if I do decide to replace the throttle body.
Assuming the transmission is sound, then my
next
pursuits would be toward spark or fuel, to include TB or even the computer. I had an AOS go on a
986
and was quite evident, my guess is you would know. If you replace it that's not a bad investment, you don't have to see it as a waste. Good luck.
Not over the past weekend, but early this afternoon. Installed the starter within a hour!!! It went pretty smooth. First disconnected the battery!! Remove the throttle body, carefully mind the hoses that are attached under the plenum! The starter bolts are in fact mounted by E14 bolts, the 12v lead is 10mm, and the battery lead is 13mm. Replaced the starter with a new Bosch unit! While pondering my thoughts I decided to order a new throttle body as well. The plenum had just a small coating of oil on it! Checked the actuator valve on the plenum and it held vacuum and moved freely. Cleaned the plenum all up! The old throttle body was not too bad in terms of carbon/gunk. Installed the new throttle body with new gasket. Reassembled the rest and battery reattached and she started up like a charm!!! Checked the AOS hoses all again to make sure I do not have any cracks, nothing to report and held air by blowing through them.
Going to test the system for the
next
few weeks to report back. The initial application of the gas pedal while taking off from a standstill seems more responsive. Attached a few pictures as well!! The battery was out for over four hours as I made a quick trip to the parts store for the throttle body gasket and some lunch!!
I'm going to assume all adaptations are clear, but did leave the ignition switch on for 5 minutes without starting it to make sure the throttle body was able to find its settings/reference point. Let us pray!!!!!!:gossip:
Well after many months and miles I have one sweet ride!! She actually improved gas mileage wise and oh the response!! Even drove through the mountain one weekend hitting the 77,777 mark!
