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Engine hesitation/power 'blip'


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Here's the next one. I did not notice this one for the first couple of weeks, then I went on holiday for a couple of weeks (and left the car standing), and now it seems to have another little problem.

99% of the time the power delivery is fine. But occasionally, there seems to be a little 'hiccup'. At first I thought it was the clutch slipping, as it felt similar to the effect I managed to achieve a long time ago on a car with a burned out clutch, but I am not so sure now.

Normally, it is most evident under 'casual driving' in 2nd, when accellerating from a steady 2K (ish) rpm, but today it did the same in 3rd. After holding steady for a while at about 2K rpm, I pressed the gas pedal a little harder and it seemed to kill the power a little (or sort of 'pull back') before jerking forward and starting to accellerate. Now, as I said it doesn't do it all of the time... in fact, about once or so per run seems normal. It is also most likely to happen when I've been running the car, have stopped the engine for a while, and then re-started with the engine semi-warm. Strangely, even then it doesn't seem to do it straight away, it's usually a minute or two into the drive.

The problem is, if I drive the car a little more spirited (but still under 4-5K RPM as it's running in!) it seems perfectly fine.

This one has me stumped. I've wondered wether it's an e-gas issue, fuel blockage, ecu problem... but I just don't know enough about these cars to work it out for myself. It's also not bad enough to return the car to the dealer (unless someone tells me otherwise), but it's made me a little nervous!

Can anyone suggest an explanation... or a cure?

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I've heard this before about the MY03 VarioCam Plus programming. I've heard two stories -- one that this can be somewhat improved with a software upgrade (though I have not seen a TSB on it) and two that this is the way it is. Perhaps some MY03 owners can respond...

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Weak fuel maybe? Try some fresh gasoline with the highest octane you can find from another gas station and see if the problem went away. It could take some time because of possible self updating software. That's my thought. :lightbulb:

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Rather than looking at which gear it hiccups in, pay close atention to at what RPM it hiccups. Gentle acceleration under any gear, there is a VarioCam hiccup anywhere from 2800 to 3200 rpm, followed by a gentle "kick in the behind" as the engine not only catches up but seems to pull harder. Since I've put in PSE, I've noticed this hiccup is also followed by a subtle change in the exhaust tone.

If that's what your car is doing, I wouldn't let it bother me too much. It only happens when I am accelerating so gently I would have upshifted before the hiccup rpm anyway. If the rpm goes beyond 3K, I'm usually accelerating hard enough that the hiccup doesn't happen or is unnoticeable.

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It can also be the e-gas programming. There was a good article on e-gas in a recent Pano. The e-gas is tied into the DME and is used to smooth the power delivery and control emissions. A friend of mine who has done extensive work on a dyno with e-gas 996's tells me the e-gas controller is slow to pick up when you accelerate from partial throttle unless you mash the gas. This is on purpose to both smooth the power delivery and control emissions.

However, in your case it doesn't sound like it is smoothing the power delivery but is making more jerky. If the problem doesn't appear to be the Variocam situation that Palting and Loren pointed out, have you dealer run a diagnostic on the e-gas controller.

Karl

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Gary....There is one other, very remote, possibility. Have you had any work done recently on the clutch pedal action or return spring to address funny noises? The DME/eGas programming senses the position of the clutch pedal. If the sensor is not retsored/adjusted after the work, you can experience something like what you are feeling. BTDT

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This hiccup you describe is the change in Variocam settings. It annoys the hell out of me too but there's nothing you can do about it unfortunately, I've investigated it. Boxsters apparently did this as well around year 2000 but a 2003 I drove a few weeks ago was silky smooth from 0-6000RPM with no "kick in the pants". You'll notice this in 1st>2nd>3rd gears under light acceleration. It's noticible to new driver's too as my friend whose never driven a 911 before (poor schmuck) thought it was the turbo kicking in (non-turbo 996). Sorry man but I think unless you disabled the Variocam shifting through software or something radical like this I believe you're stuck, but rest assured there's nothing "wrong" with your car.

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Thanks everyone.

I tried to replicate the problem this weekend... but to no avail! I guess my C4S is living up to her name (J-Lo) in being a little diva-ish and tempremental!

I am not sure the original problem was the variocam, as it was much down closer to 2K rpm than 3-3.5K, from memory. I've put it down to weak fuel/standing for two weeks/break-in-hiccups until it happens again. The closest I got was what felt like insufficient revs or too high a gear to pull properly, which is driver error, but other than that it was fine.

I also went for a 'quick' drive last night (in both senses of the word), keeping it under 4.5K rpm but pushing hard up to that level. Oh wow... now I know what people mean about the 911 being a bit fast. I can't wait to open her up properly, but even "with the stabilisers on" it was one hell of a blast!

Cheers,

Gary D.

Edited by GaryD
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  • 1 year later...

I have a MY03 and have experience this on very gentle and light acceleration. Should I not worry about this for the variocam is what it is? Or should I just drive harder and not shift until 4k? Would the newly installed FabSp cold air intake have anything to do with this?

:drive:

It can also be the e-gas programming. There was a good article on e-gas in a recent Pano. The e-gas is tied into the DME and is used to smooth the power delivery and control emissions. A friend of mine who has done extensive work on a dyno with e-gas 996's tells me the e-gas controller is slow to pick up when you accelerate from partial throttle unless you mash the gas. This is on purpose to both smooth the power delivery and control emissions.

However, in your case it doesn't sound like it is smoothing the power delivery but is making more jerky. If the problem doesn't appear to be the Variocam situation that Palting and Loren pointed out, have you dealer run a diagnostic on the e-gas controller.

Karl

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  • 2 weeks later...
I've heard this before about the MY03 VarioCam Plus programming. I've heard two stories -- one that this can be somewhat improved with a software upgrade (though I have not seen a TSB on it) and two that this is the way it is. Perhaps some MY03 owners can respond...

I also experienced this problem with my '03 Targa. The car would surge sometime so much I'd have to apologize to my wife so she wouldn't think I was nailing the throttle. Notice that this comment is now in 'past tense'. :clapping:

I took my car back to the dealer 3 or 4 times with this issue within the first 4 months thinking something had to be wrong. They replaced a part from a new car onto mine under the guidance of Porsche Tech support who studied a whole sheet full of diagnostic information that the dealer sent them. The local tech rode in my car with the computer hooked up and the issue was the Variocam programming. You could see it on the computer, feel it, and hear it every time it changed. They agreed that it seemed pretty severe in my car before they changed the part. Even with the new part, the problem was lessened from "neck breaking" status, but it never went away. I resorted to live with it.

Thanks to this thread, and one I saw on another forum, last week I ask my dealer if there were any new revisons of 996 DME software, and would they update the software on my car. I took it in yesterday and they updated the DME. I can hardly believe it, but the surging problem is solved. Once in a while I feel a little bit of it, but it is all but gone compared to what it was before. I don't know what version of S/W they installed, but the tech indicated that it is the latest release.

Hopefully you all can get the same results. I am ecstatic. :cheers:

Dwayne

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it's the variocam profile switching over at 3250 rpm. I have a 03 C4s and I can replicate it at will. I doubt it's the egas because it doesn't happen when you accelerate rapidly. It only happens when you are coasting and then decide to accelerate.

The cam's duration/lift changing would explain the change in the power curve and the not so subtle engine output.

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  • 1 year later...

Thank you guys! I swapped in my 987 for an 03 996 last w/e and that very same problem was driving me nuts ! I was starting to worry !

I had it pegged at 3200 rpm, so 3250 is close enough ;-) I will ask the dealer to check my DME for a software update but barring that, will learn to live with it too !! One less worry !!!

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Thank you guys! I swapped in my 987 for an 03 996 last w/e and that very same problem was driving me nuts ! I was starting to worry !

I had it pegged at 3200 rpm, so 3250 is close enough ;-) I will ask the dealer to check my DME for a software update but barring that, will learn to live with it too !! One less worry !!!

Trust me, after a few months it comes so normal you don't notice it anymore. Enjoy your car!

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  • 3 weeks later...

My '02 C2 does the same thing. It bothered me at first, but if you push the car a little harder, it is less noticeable.

Funny how some of these things that are so annoying can be lived with once we realize we're not crazy. Temperamental beasts, these cars....

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  • 13 years later...

Hi guys! I've been experiencing something similar but I am getting a bit of "pullback" right after 4k RPM under hard acceleration. It's almost as though the power just kicks in and starts to pull hard then all of a sudden it drops off. It does it in different gears at different points. The fuel was old, but I've since filled up the tank with Premium fuel. Any ideas? Thanks!

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51 minutes ago, BLKMRIAH said:

Hi guys! I've been experiencing something similar but I am getting a bit of "pullback" right after 4k RPM under hard acceleration. It's almost as though the power just kicks in and starts to pull hard then all of a sudden it drops off. It does it in different gears at different points. The fuel was old, but I've since filled up the tank with Premium fuel. Any ideas? Thanks!

:welcomeani:

It would help if you tell us the exact model and year of your car...

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