Throttle Position Sensor?

Looking for input, or any members previous experience or knowledge with this issue I’m having. Vehicle: 2008 Boxster base model, 5-spd manual, 50k miles. Problem: Issue just started over the last month or two, intermittently. When starting from a stop, at a light or pulling out of a parking lot or driveway, there is a slight ‘stumble’, the car begins to accelerate but occasionally has a ‘hiccup’ or stumble that lasts for a second or two. While cruising at regular speeds and the pedal is depressed there is smooth acceleration, no stumble or hesitation. Have to add that I have a Sprint Booster but this has been in use for nearly two years with no issues. I‘ve tried deactivating the SB by clicking from Sport to Race to Off thinking that might be causing the issue but it persists. My first thought was possibly a bad Throttle Position Sensor but when I searched the usual parts supplier’s, Pelican or FCP euro, there is no part listed. Further searching on this forum seems to indicate that there is not a typical TPS mounted on the throttle body, but is integrated into the accelerator pedal. Apparently 986 models had the TPS mounted on the throttle body, but it was incorporated into the pedal assembly from the 987 on. Others experiencing this have also reported this problem seems to crop up in cooler temps. Not one to enjoy replacing parts without a more concrete diagnosis, and the fact that a new accelerator pedal is over $450, does anyone know any parameters for testing the pedal mounted sensor with a multimeter ? I believe it may be something such as a potentiometer, so what values should I be reading when depressing the pedal? I might start with just disconnecting the Sprint Booster altogether to rule that out. Also might try removing the pedal assembly and attempting to spray some electronic contact cleaner into the sensor to see if that has any effect. Anyone experience this or have any ideas? All input appreciated.

I think that removing the SB and cleaning up the pedal are the same steps I would try. If it turns out that the issue is the pedal itself, you may want to consider other alternatives to the OE one. For that price there are some very high quality pedals available.

I don't have an AllDataDIY subscription for the 987.1 cars (if anyone wants to gift me one, it might be useful here once in a while..) but here is what the 987.2 system looks and works like. On the 987.2 the throttle position sensors are two fold.. x 2 - at both the pedal and the throttle body assembly. The pedal assembly has two potentiometers - the value of these two is compared in the DME and used to detect if one of them has gone bad. If it goes bad it should throw a code in the DME and use the still working one possibly to allow you to limp home (dunno anyone who has experienced the failure..) Then on the actual throttle body - a similar scheme is used to determine what the opening position of the throttle body is - dual potentiometers again - checked by the DME... I have no idea of what the value of the potentiometers is supposed to be - but a quick check with an Ohmmeter would tell you if the values increase/decrease smoothly with throttle position changes. Any dead spots should show up that way.. and if you have a diagnostics tool that can read the DME - it should be able to give you the value of the potentiometers for any given throttle position by simply stepping on the pedal with the ignition on. There are two valuable tools for the DIYer (and I can't emphasize this enough - not having these is like trying to perform surgery blindfolded..) AllDataDIY Subscription Porsche Specific diagnostics tool The cost of one avoided dealer service department visit will cover the cost of these tools. Think on that for a bit.

Thanks for the info, Don. And as per your suggestion, on my list for near-future purchases is a Foxwell NT- 530 diagnostic tool. I found a new OEM throttle pedal assembly from delawareporscheparts that contains the new TPS integrated into the assembly. If my other diagnostic efforts don’t turn up any obvious issues then I might opt to replace it. Might pay a visit to my indie to see if his scan tool reveals anything.

Just went to the Foxwell website, and they are offering 5% off with an emailed coupon, at a list price of $159, but lo and behold, but claims they are Out of Stock. Amazon has them at $169 and I will purchase from them most likely. My only further concerns are that from reading other posts, most users have high regards for the device’s capabilities but some have expressed confusion with the lack of guidance, and the fact that it comes with minimal instructions or documentation. Can anyone weigh in on their experiences with navigating the Foxwell with the scant instructions provided? Hopefully these issues can be addressed with the help of our ever-present Porsche community.

There isn't a lot of guidance or documentation from foxwell in terms of specifics for Porsches but it's pretty straightforward to get it to work and there are a lot of threads on how to do specific tasks here and on the other Porsche site. I managed to program a new steering wheel on my car and resetting service intervals is easy. Mind you if I didn't already have my Foxwell I'd go this route - PIWIS 3 for $75

I'm working on having both (and my Durametric, and the other one I own.. forget the name..) oh, and I have 2 Foxwells...