I'm curious if this is normal with my 991S with PDK?
When I initially accelerate, it seems as if the car hesitates to go. This happens when I am trying to go quickly from a standstill in normal mode of operation. When I switch to shift on my own, it doesn't seem to happen at all, or is less noticeable.

Anyone else experience this? Is it normal?
This is my first Porsche, so I thought I'd ask before wasting time going to my dealer to get it checked. Kinda reminds me of my diesel X5.

 

You're in regular, non sports plus mode, or fuel economy mode as I like to call it. The car lacks low end torque to pull off the line until you boost the RPM. The PDK in normal mode tries to reach for the highest gear possible for fuel savings. I hope you got Sports Chrono Plus with the car.

 

I used to have a problem that was similar to the one you have described. You get on it and before the RPM builds there's what seems like a half second delay. Then the RPM builds without clutch slippage. In my 991, When I get on it, the RPM immediately goes to 2500-3000 RPM and then the clutches lock up, providing a much improved acceleration experience. When I don't get on it hard, it locks up immediately. This is much like a launch control start, but more limited and I am in normal mode.

ChuckJ
PS: Where did you buy your car?

 

I do have the Sports Chrono on my S, and yes, this happens in normal mode, no sport, or sport plus mode.
It almost feels like it's a lack of fuel to the car or something.
I notice if I ease into accelerating, it doesn't happen, but when I try to accelerate faster, it hesitates. I can't time it, but it's long enough for me to react by letting my foot off the gas, and then reaccelerating.... if that makes sense.

For the life of me, in almost 1500 miles on the car, I can't think of this happening until recently. Not sure if it's due to me not trying as hard in earlier mileage as I was worried about break in.

 

I'm getting a taste of this same thing on my car too. When turning onto a busy street I need to put my foot into it much more then you'd expect. Not happy with the problem but glade to hear that I'm not alone.

 

I don't have a 991 or a PDK but the first thing I do when I get into my car is hit the SPORT button.

 

If it's doing this after it's warmed up and you're using premium gas, maybe you should change gas brands. I suspect that the car can tell when it doesn't have > 91 gas and it changes the timing.

ChuckJ

 

^^ Maybe this? I usually go to the same gas station. This happens whether the car is cold, warm, doesn't matter. I always use premium gas.
Maybe I should try using the sport or sport plus and doing the same thing and see if there is as much hesitation.

 

Does anyone know what sort of petrol is recommended for 991?

 

SEATTLE BUM : I am with you. I have a 991 S. I get in. Sport mode on. Parking brake off. Start car. Enjoy.
I use premium at Shell and have never noticed a problem. Every single day and every single shift is a pleasure in this car.

 

I'm going to go out on a limb here. I agree (991 3.4 manual w/sport chrono) and here's my lay enthusiast explanation:

Perhaps b/c the 991 was designed around the pdk, the new engines (they both have similar torque curves) have a more "modern" power delivery. Think M3 V8. They have enough low end torque to satisfy, but they pack a wallop up high in the rev counter. They are essentially 2 engines in 1: low end settings and then the engine adapts to high end settings somewhere after 4000 rpms (valve and ignition timing, exhaust back pressure and intake tracks - all change) In my opinion, its the void between the changeover that we are all noticing. The engine is in transition and it delivers neither torque nor hp for @1000 rpms from 4-5k. The 997 engine was a 1 horse show: low end torque somewhat conventionally turned into hp at a modest rpm. This new engine is a torque engine down low that becomes a hp engine way up high. With the ability to click the pdk lever a few times to get you in the sweet spot on the rev counter, this new power curve makes sense. I find the downside of this new power delivery is that (like a V10 M5) you find yourself going faster than you'd like to get that rush of acceleration b/c its from 5500-7500 rpms. Whereas it was 4k-6k in the old car. No need to hit redline before really. The new car is faster in a dictionary definition of the word (on a track for example), but the old engine felt like it had a tad more punch on the road.

Anyone else agree?

 

I believe a poll a while back showed that most 991 owners leave sports mode on all the time. As a 991 S PDK owner, I can attest to the fact that if you enjoy a responsive car, and we all do, you need to leave sports mode on all the time. I find my gas mileage to be decent and it doesn't harm the car at all. Push the button and drive the car you deserve.

 

I have a 997.1 mt and I experience slight hesitation when the motor is cold. I do notice that the hesitation goes away with new spark plugs. An earlier person noted that the cars run lean. So you maybe experiencing some early fouling of plugs? So try a different gas supplier perhaps? I do agree the 997 sweet spot is between 3 and 5 krpm and you really don't need to redline it to have fun on the streets. Of course both cars are awesome and as you get in tune with them you start picking up on very small issues.

 

This is the answer.

 

My November 12 build C2S had the throttle hesitation. When flooring it in any mode you would first get about a 1/2-1 second minor increase in RPM (about 100) before the clutch would pretty much fully engage and then RPM allowed to increase.
I used various techniques to get around this like left foot on brake, then throttle then let go of brake.

Anyway - car was due for its first 10.000 Km oil service so I took it to the dealer. They informend me that the car needed its "control unit" updated and it had something to do with the PDK but did not know any details.

I am very pleased to say that the update completely removed the lag and also "fixed" the somewhat lacklustre gear changes in Sport+ mode. They are now really violent - it even surprised me to get a good thump in the back when it changed gears at 180Km/h after a launch.

Flooring it now in any mode (not launch control) gets the RPM to rise rapidly instantly with some clutch slipage to support - recon at about 4000 RPM or so the clutch is fully engaged. Pretty much perfect in my book now.

If your car has this lag - take it for the update. It almost changes it into a new car. Just feels different now. The way it should.

Rainier