Born a Longhorn

2015 C4S 7MT with 60k miles, second owner since last year

Engine developed a tendency during the winter months to "hesitate" most notably at ~1600-2000rpm during light acceleration. Think bringing the car up to speed on city streets, then cruising at 35-40mph in 4th gear... the throttle fights me, and "surges" between the requested throttle and less than that. The hesitation almost feels like the engine is starved for fuel/oxygen briefly, then catches its breath and rockets off like a turbo has kicked in. I initially chalked it up to winter, but it has persisted in the 100deg Texas heat. It only improves mildly but doesn't go away even once the car is up to operating temperature for coolant and oil.

Bought it with 52k miles and it wasn't doing this for the first 5k miles during a variety of conditions. I just did the 60k service myself (oil/filter, engine air filters only), along with two tanks of 93 with Techron fuel system added, and the condition didn't change. It doesn't feel like a misfire problem, and no codes are being thrown. I have an iCarSoft POR V2.0. I will say that I was negligently running 91 octane from various brands at first... now that I've google mapped the two stations with 93 Top Tier within an hour of my house, I know where to go for fuel from now on.

Any ideas? Do I need to just stay the course with good gas until it improves? Car is perfect otherwise!

Born a Longhorn

Update: it just threw the P2101 code - Throttle Actuator A Control Motor Circuit Range/Performance. Limped it home in reduced power mode. Guess I was right about it being a throttle issue. Off to the local indy unless someone thinks this is a quick fix I could do at home (sucks that just had the bumper off two days ago...).

Jack F

Booo. Keep Ipm’s posted. Hopefully an affordable repair. How do you like the car?

Joec500

I got this code and and it gave me a limp mode. I reset the car and everything worked great for about a week, when it returned. I ended up just replacing the throttle body with a Bosch Unit I bought from Autozone (OEM manufacturer for Porsche) for about $150 with coupons.

Took me about 1-2 hours start to finish. Most shops will probably bill 2-3 hours for this job as you do need to remove the bumper, and airbox to get to the part.

My guess is a trustworthy indie will charge 500-800 parts and labor for this job depending where you live. Unless they buy the Throttle Body from Porsche, which I think is around $600 versus $150 - $200 for the same Bosch unit without the porsche stamp.

Born a Longhorn

Love the car... reminds me of a hyper version of my Audi S4 6MT (with a much different F/R weight distro). Once I get this throttle issue sorted, I'll be a happy camper. It's a psuedo-daily driver and I'd like to rack up plenty of miles on it.

Joec500, I did the code reset like you, and for now it has gone back to normal. I will plan to do the throttle body replacement if it comes back again... I can handle that. Confirm that's all you did and it hasn't come back since?

Joec500

yup did the swap months ago and driven 1-2k miles. Has not returned

Joec500

Just in case, this is the Bosche Throttle body for our cars. 991.1 C2S with the 3.8 9A1 motor.

https://www.fcpeuro.com/products/por...vD_BwE#fitment

Born a Longhorn

Much appreciated! I'll keep this thread updated on how it goes. Good to know I'm not the only one.

Born a Longhorn

Update: just like @Joec500 , made it about a week and then the code threw again with reduced power mode. Fortunately I had already ordered the replacement Bosch throttle body. A few hours later along with code fault clearing, it's all back to normal again. Throttle response is like new.

For those that run into this issue in the future, the onset of symptoms was pretty gradual for me, over the course of several months and several thousand miles. If the throttle response and idle seem out of whack, get in front of it and order a new throttle body and have it ready. You don't want to be stuck in reduced power mode far from home or the repair shop. I'm only moderately mechanically inclined, and I had little trouble doing the replacement myself.

desmotesta

thanks for the update

Refreshing to see posts like these that are interesting and provide value.