Porsche_nuts

I found this on the Soler. Easy peasy install. They also talk about the smoother response from stop toward end of vid. Seriously thinking of doing this. Can't hurt.

__ Charley __

Ok So after all solenoids and throttle body changed i have to say, for me, what did the difference is the TB.
Solenoids are New but i havent notice any change till Now..
Ill Keep you in touch.. But after TB change, no more hesitation or stumble.. Car is really great... I am very happy to did that change!!

BaltimoreHokie

Question for you. I know you did other maint. items but was removing the bumper necessary for only changing out the throttle body? Any lights afterwards? If so, Did they clear on their own? The video above made it look pretty easy on the GT3, wondering if its as easy on the 991.1 S

koala

I think it would be possible to replace the TB without removing the airbox and bumper. You just have to hope you can get enough leverage on the rubber hose that connects the airbox to the TB and hope that you can remove it in that confined area. That said, even though I'm a small guy with small hands, I'm not sure I'd want to do it that way.

I didn't have any codes or errors as I knew about the throttle reset procedure from others on here. All you have to do is turn the ignition on (without starting the car) and let it sit for 30 seconds. This procedure will reset the throttle sensor calibration.

As an aside, I still notice that if I do the throttle reset before a drive, that the car behaves better. This is perplexing to me given that I have replaced the TB.

koala

So glad that worked for you! The only thing that seems to help me is to continue resetting the throttle position sensor before each drive. I just did that this morning on a nice -2 C drive to the office and the car ran beautifully.

I'll still replace my variocam solenoids over the winter as I really want to get this nailed down one way or another.

BaltimoreHokie

Thanks for the info. For you, or those of you who have had and do have the stumble. How often is it happening? I feel like I've felt it once, but so far I cant replicate it. This forum also makes you look for things...etc. haha.

koala

On a typical drive, I can reproduce the stumble very easily. It's especially noticeable when the car is cold. When it's warmed up, it's less obvious. But, even on the highway if you have it at, say 2,100-2,200 rpm and then apply light throttle, there is an immediate thump/skip type of feel.

The easiest solution is to drive above 3k rpm, but I prefer not to do that until the oil is up to operating temp

JW911

FYI everyone. Advance Auto parts is offering a cyber Monday 20% off deal which will generate a net price on the Bosch throttle body of $135.99. (Code: BLACKFRI) I am on the fence on ordering this now. I have been experiencing occasional hesitation from a stop for about 2 years now. I hit the gas pedal and the car just stands there for about half a second and then it lurches forward. It happens very randomly and is not dependent on temp or anything else. It sure feels like the throttle is briefly failing to acknowledge my right foot and then suddenly it does. So, a problem with the electronic throttle body or sensor makes sense. I haven't bothered to bring it in to the dealer because I am sure they will charge me for $180 in labor and be unable to duplicate the problem. I don't have any sign of the 2,200+ RPM stumble so I am purely trying to solve the hesitation from stop issue. This thread seems to contain stories of both problems which makes it hard to follow and to further complicate things, some folks seem to be experiencing both the stumble and hesitation from stop issue.

Can anyone who replaced the throttle body provide an update as to whether the hesitation from stop has permanently been cured?

the_buch

By chance is your transmission PDK and do you experience what you're describing when the HOLD assist is activated? If so, you have to ease into it a bit from stop as the software does not handle this scenario well.

JW911

No, it is not hold assist related. Level ground, like pulling away from a stop light or yesterday, pulling away from my mailbox on a level road.

polobai

Try the sprint booster and see if it makes a difference?

JW911

Thanks but I would prefer to solve the root cause by fixing the malfunction rather than gambling that an add on device like sprint booster will compensate and cure it.

koala

I replaced my variocam solenoids over the weekend and I can report that, at least so far, the stumble is 100% entirely gone.

It used to be very easy for me to reproduce the stumble at 2,200 rpm and I simply have not been able to reproduce the stumble since changing the solenoids.

This was a DIY job. They're located in the same area as the spark plugs. The passenger side was more difficult, but that could also be because I did that one first. I posted a few pics here: https://rennlist.com/forums/991/1267...l#post18052812

I understand there are also two solenoids for the valve lift, but I've purposefully left those alone as I didn't want to just arbitrarily replace parts all in one shot. Made more sense to me to try one thing at a time (and to save some money of course!).

Joec500

Nice. I wonder it's just a matter of debris gunky up the solenoids causing them to react slower and then once the oil heats up and gets less viscous and frees up the movement? Hence everything works better at warmer engine temps. Also I noticed you are in a colder climate than myself in Southern California that could possibly play a role too?

I think at my next oil change I will just proactively swap mine as I am approaching 100k miles.

pfan

Possible, however it wouldn't explain why the stumble only occurs at a specific rpm. ???????.
Also, many of us have experienced it from day one.