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    May 16, 2007 7:30:30 PM

    Uber
    Newbie
    Uber
    Loc: UK
    Posts: 4, Gallery
    Registered on: May 16, 2007

    997S Flat Spot

    Hi All,

    I've had my 997s for over two years now, and the flat spot that happens around 3000RPM is really starting to get me down.

    It always catches me out when overtaking whilst I've got the HiFi loud & I'm chilled out..and not really gunning it!

    Has anyone come across a fix for this (apart from using the "S" button all the time)?

    Thanks

    Steve

    May 16, 2007 8:04:05 PM

    beltar
    Veteran
    beltar
    Loc: belgium , Belgium
    Posts: 1232, Gallery
    Registered on: Mar 15, 2005
    Reply to: Uber

    Re: 997S Flat Spot

    Quote:
    Uber said:
    Hi All,

    I've had my 997s for over two years now, and the flat spot that happens around 3000RPM is really starting to get me down.

    It always catches me out when overtaking whilst I've got the HiFi loud & I'm chilled out..and not really gunning it!

    Has anyone come across a fix for this (apart from using the "S" button all the time)?

    Thanks

    Steve



    this...

    May 16, 2007 8:38:12 PM

    Dan L
    Expert
    Dan L
    Loc: Santa Barbara, CA , United States
    Posts: 1957, Gallery
    Registered on: Jan 2, 2006
    Reply to: beltar

    Re: 997S Flat Spot

    Some are beginning to swear by this device:

    http://roadsportsupply.com/IPD_Plenums_Porsche.html

    Listening and looking for now.

    Dan

    May 16, 2007 9:36:12 PM

    Uber
    Newbie
    Uber
    Loc: UK
    Posts: 4, Gallery
    Registered on: May 16, 2007
    Reply to: beltar

    Re: 997S Flat Spot

    Quote:
    beltar said:
    Quote:
    Uber said:
    Hi All,

    I've had my 997s for over two years now, and the flat spot that happens around 3000RPM is really starting to get me down.

    It always catches me out when overtaking whilst I've got the HiFi loud & I'm chilled out..and not really gunning it!

    Has anyone come across a fix for this (apart from using the "S" button all the time)?

    Thanks

    Steve



    this...



    WTF is that a turbo upgrade??

    May 16, 2007 9:54:22 PM

    Adam2S Offline
    Senior
    Adam2S
    Loc: UK , United Kingdom
    Posts: 745, Gallery
    Registered on: Feb 19, 2007
    Reply to: Uber

    Re: 997S Flat Spot

    I think its called an exhaust!

    May 16, 2007 10:03:34 PM

    ResB Offline
    Rennteam Pro
    ResB
    Loc: Yorkshire, where roads are twisty... , United Kingdom
    Posts: 2858, Gallery
    Registered on: Jan 19, 2006
    Reply to: Adam2S

    Re: 997S Flat Spot

    I've had my ECU upgraded by DMS and the flat spot is still there. So don't do that. In fact it caught me out recently when I was least expecting it. Sorry Lorry driver who ever you were!

    May 17, 2007 1:48:38 AM

    pcosta
    Co-Pilot
    pcosta
    Loc: New Canaan, CT, USA , United States
    Posts: 236, Gallery
    Registered on: Jul 17, 2004
    Reply to: ResB

    Re: 997S Flat Spot

    I haven't experienced a "flat spot". Don't know if it is due to X51, but never felt any hesitation on the engine

    May 17, 2007 2:25:19 AM

    jerrygee
    Junior
    jerrygee
    Loc: Julian, CA
    Posts: 95, Gallery
    Registered on: Apr 2, 2006
    Reply to: Uber

    Re: 997S Flat Spot

    I don't know what flat spot you are referring to but my advice is to drop down a few gears when you need to gitty-up and go to overtake slower traffic. Whereas the 997S engine does offer useable low end torque, when you really want to move out you need to drop it down a few gears and rev it.

    The "S" button will not add any power and make up for your lack of paying attention. The X51 kit, aftermarket exhaust, miracle plenums and the like will not improve the normally aspirated 3.8 liter engine down low in the rev range to ever make it a low end stump puller. If you want or need lots of power at 3,000 rpm you need to get a Turbo.

    May 17, 2007 5:51:11 AM

    Nad
    Junior
    Nad
    Loc: London , United Kingdom
    Posts: 75, Gallery
    Registered on: Sep 18, 2006
    Reply to: jerrygee

    Re: 997S Flat Spot

    Disagree....X51 takes care of the lack of low end torque nicely....its an expensive option but one which I am enjoying very much....

    May 17, 2007 8:12:56 AM

    MBW_UK
    Junior
    MBW_UK
    Loc: Surrey, UK
    Posts: 134, Gallery
    Registered on: Feb 1, 2006
    Reply to: Uber

    Re: 997S Flat Spot

    Quote:
    Uber said:
    Has anyone come across a fix for this (apart from using the "S" button all the time)?
    Steve




    Haven't had a probelm with a flat spot, but you could give this a try.

    Edit : Image wouldn't imbed, serves me right for trying to be cocky! Pictue in the attachment, but the jokes died I'm afraid!!!

    /uploads/350165-997sManual.bmp

    May 17, 2007 8:30:45 AM

    easy_rider911
    Rennteam VIP
    easy_rider911
    Loc: London , United Kingdom
    Posts: 22190, Gallery
    Registered on: Nov 8, 2004
    Reply to: MBW_UK

    Re: 997S Flat Spot

    I think the 3.8L Carrera S engine has enough low end torque (i.e. below 2000rpm) and top end torque (i.e. 4500rpm and up). The 'problem', if there is one, is with mid range torque (i.e. 2500-3500rpm). Then suddenly above 4000rpm the torque kicks in again. The X51 provides a little more torque all through the range BUT provides A LOT more torque low end (i.e. below 2300rpm) and high end (i.e. 5000rpm to redline). This graph should illustrate my point.

    May 17, 2007 2:54:37 PM

    MMD
    Rennteam VIP
    MMD
    Loc: usa
    Posts: 9652, Gallery
    Registered on: Dec 16, 2004
    Reply to: easy_rider911

    Re: 997S Flat Spot

    Happens with me too. I'm no expert but it seems perhaps the first gear is too low. My "flat spot" is when the engine is really winding out, with no "thrust," and screaming to be shifted into second.

    May 17, 2007 3:14:18 PM

    jerrygee
    Junior
    jerrygee
    Loc: Julian, CA
    Posts: 95, Gallery
    Registered on: Apr 2, 2006
    Reply to: Nad

    Re: 997S Flat Spot

    Quote:
    Nad said:
    Disagree....X51 takes care of the lack of low end torque nicely....its an expensive option but one which I am enjoying very much....


    If you look at the power graph supplied by easy_rider911 you will see that the 997S and the X51 997S have identical power output from 3,000 rpm to 3,500 rpm. Like I said in my original post the 997S makes useable power down low but if you need to accelerate in a hurry you need to drop down a gear or two or three.

    I am very familiar with of the power characteristics of the X51 kit as I have close to 10,000 miles on my X51 kit equipped 2007 997S. Even with its improved low end torque it still needs to be revved to produce its peak power.

    May 17, 2007 6:48:25 PM

    Uber
    Newbie
    Uber
    Loc: UK
    Posts: 4, Gallery
    Registered on: May 16, 2007
    Reply to: jerrygee

    Re: 997S Flat Spot

    I've been told by my OPC that this is due to the varicam... But there must be a fix (or re-map) as the flat spot is not there in sport mode..

    I wonder at what revs the varicam changes whilst in Sport mode compared to normal?

    May 17, 2007 8:22:06 PM

    ResB Offline
    Rennteam Pro
    ResB
    Loc: Yorkshire, where roads are twisty... , United Kingdom
    Posts: 2858, Gallery
    Registered on: Jan 19, 2006
    Reply to: Uber

    Re: 997S Flat Spot

    It happened to me recently as mentioned earlier, but should have said why. Basically, wrong gear and not paying attention. However, I was in a high gear granted but "normally" the car would pull through steadily from at least 2,000 rpm in the same gear but for some reason, this time it freaked me out how noticeable the flat spot was. It really did catch me out and didn't expect it at all. Could have been a combination of things, high gear, low speed (it was a lorry I was overtaking) and the fact I'd just caned it immediately before and the engine was quite hot. It may have even been an intermittant fuel issue. Em, think I'll get it checked out come to think of it.

    May 17, 2007 9:10:49 PM

    Uber
    Newbie
    Uber
    Loc: UK
    Posts: 4, Gallery
    Registered on: May 16, 2007
    Reply to: ResB

    Re: 997S Flat Spot

    I know what you mean.. I really notice it when in 2nd & 3rd gear.. and then flooring it...2000-3000 revs a smooth acceleration 3000-3200 nothing..then WHAM!! here we go again..


    So is it only my 997 that has this?

    May 17, 2007 9:42:13 PM

    Le Chef
    Veteran
    Le Chef
    Loc: Chicago , United States
    Posts: 1059, Gallery
    Registered on: Jul 3, 2003
    Reply to: MBW_UK

    Re: 997S Flat Spot

    Don't have a problem. I think the engine management system learns your driving style and tailors the engine response to it. I know if I just drive in town the engine feels lazy to rev. If it's been driven on twisty roads or the track it feels much more eager to rev. But on this model I can't say I've felt a flat spot. On my old 996 I could feel it, but that was because I was being too gentle with it. Once pointed out I never had the problem again.

    May 18, 2007 2:42:49 AM

    Bluehinder
    Junior
    Bluehinder
    Loc: Colorado
    Posts: 134, Gallery
    Registered on: Mar 18, 2007
    Reply to: Le Chef

    Re: 997S Flat Spot

    Sounds like a Turbo is in order. You'll never be happy now.

    May 23, 2007 6:20:25 AM

    IanW
    Newbie
    IanW
    Loc: Manchester, UK
    Posts: 1, Gallery
    Registered on: May 21, 2007
    Reply to: easy_rider911

    Re: 997S Flat Spot

    Interesting to see the torque graphs easy_rider911 posted. They show in black and white the TWO very noticeable flat spots that the 997S has. Try this - find an open space and do a full throttle pull in second gear from about 1500rpm. You'll notice the car pulls strongly until just over 2000rpm then it just stops pulling any harder until about 2700 rpm. It will then light-up, pulling strongly through 3000 and 4000 rpm then goes flat again through 5000 rpm. It then lights up once again at 5500 rpm for a rush to the red line at 7400.

    I've noticed these 2 'holes' in the power delivery of the car ever since I've had it. It's been checked over several times and everything is working normally. I've always thought something was amiss but here are factory graphs showing the torque output of the engine flattening out exactly where I've felt it.

    I'm amazed at Porsche letting an engine out of development with such an uneven power delivery. For me it spoils the car. No wonder so many other owners can't wait to start modifying their 997S. Looks like I'm going to have to do the same.....!!

    Ian

    Edit: PS - The exhaust pic above is the full Europipe system - nice but expensive. www.europipe.be

    May 23, 2007 11:16:51 PM

    mdrums
    Junior
    mdrums
    Loc: Tampa , United States
    Posts: 64, Gallery
    Registered on: Apr 28, 2007
    Reply to: IanW

    Re: 997S Flat Spot

    That Euro Pipe exhaust system looks awesome? During my DE's I try to keep the rpms at 4k and above. I've also found the sport button to make the throttle responce much to sensitive and that make throttle modulation and squeezing back on the gas next to impossible.
     
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