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    Mar 14, 2007 4:43:09 AM

    Pabs1
    Junior
    Pabs1
    Loc: California, USA
    Posts: 140, Gallery
    Registered on: Oct 10, 2005

    Hesitation and slight loss of Power

    Hello,
    Today I was driving on the 405 in LA from Ventura Blvd. to my house in the South Bay, I was driving between 70/85 miles/h
    ( Yeah !! For those who live or know LA quite unbelievable to drive on the 405 without traffic at around 2:00 PM at those speeds )
    Anyway as I said I was driving at around 80 m/h when suddenly the car started to hesitate and loose ( very slightly ) power and speed , I lower the gear from 5th to 4th ( ihave a tiptronic , and always drive it manually ) and the same thing, checked the oil pressure, oil temp and they were fine , checked all the warning lights, nothing, the car continue hesitating and dropped another gear to 3rd and the same, got a little concern and started to move towards the right in case I needed to stop, but then the car just drove without a problem all the way home.
    Could it have been :
    1. The road ( even thought I drove many times this route and never noticed anything unusual ).
    2. Could it had been the fuel ?
    3. The car decide to F... with me ?
    If Any of you had a similar problem or maybe have some ideas, will be very appreciated.
    Thanks,
    2006 997S


    Mar 14, 2007 8:23:48 AM

    Adam2S Offline
    Senior
    Adam2S
    Loc: UK , United Kingdom
    Posts: 745, Gallery
    Registered on: Feb 19, 2007
    Reply to: Pabs1

    Re: Hesitation and slight loss of Power

    I had a very similar thing happen to my M3 once. Was down to a faulty ignition coil affecting just one cylinder. Quick trip to the dealer and all was fine the next day.

    Mar 14, 2007 1:56:55 PM

    jte
    Newbie
    jte
    Loc: California
    Posts: 28, Gallery
    Registered on: Nov 29, 2003
    Reply to: Pabs1

    Re: Hesitation and slight loss of Power

    same thing happened to me once & my brother twice... both have 997S C4, dealer blamed gas but never was able to idendify issue and has not happened again.

    Mar 14, 2007 2:40:26 PM

    roadtrip
    Veteran
    roadtrip
    Loc: new mexico, usa
    Posts: 1172, Gallery
    Registered on: May 31, 2006
    Reply to: jte

    Re: Hesitation and slight loss of Power

    had this exact same thing happen once on another car...it was diagnosed as a faulty throttle position sensor...replaced and car ran fine

    Mar 14, 2007 3:47:29 PM

    chili
    Pilot
    chili
    Loc: Bay Area - East Bay
    Posts: 354, Gallery
    Registered on: Jul 10, 2005
    Reply to: roadtrip

    Re: Hesitation and slight loss of Power

    Same thing happenned to me twice. Both times I used Shell gas. Dealer blamed it on bad gas because they couldn't find anything wrong with the car.

    Mar 14, 2007 5:47:31 PM

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

    Re: Hesitation and slight loss of Power

    Depends on how new the car is, maybe. My brand new 986S, with about 1000 miles on it faltered and hesitated (and freaked me out). It did it once then never again. Led me to speculate there was a "burr" somewhere on the new engine parts and got stuck and then "deburred" itself and never happened again. No codes showed up at first service.

    Mar 15, 2007 10:17:13 PM

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

    Re: Hesitation and slight loss of Power

    This happened to me one time perhaps two weekends ago. It was for maybe 2 hours. I was at about 1/3 tank of gas remaining and went over to my usual place and topped it off. The problem went away. Could it be related? Do a search herein and you will find that others have had the same problem. These are complex beasts and tracing the issue to one particular component is impossible. I do not believe it is the fuel.

    Mar 15, 2007 11:49:35 PM

    GA997S
    Veteran
    GA997S
    Loc: Athens, Georgia, USA
    Posts: 1059, Gallery
    Registered on: Aug 19, 2005
    Reply to: Dan L

    Re: Hesitation and slight loss of Power

    Happened to me for about 3 miles around 5k on odo...must be # 3!

    Apr 20, 2007 2:54:08 AM

    Silver Bullet
    Veteran
    Silver Bullet
    Loc: Canada
    Posts: 1126, Gallery
    Registered on: Nov 24, 2004
    Reply to: GA997S

    Re: Hesitation and slight loss of Power

    This just happened to me on my drive home from work. Engine temp was up to operating range, all was well, and it just started jerking. The car would gradually decelerate normally, but on the accelerator and it would jerk and hesitate and certainly did not seem as powerful. As mentioned by others, normal oil pressure and no engine warnings. I was scared it wasn't going to get me home, but it did, continuing like that for the last 5 minutes.

    I've been using 94 octane gas.

    What now?

    Apr 21, 2007 7:37:50 PM

    Silver Bullet
    Veteran
    Silver Bullet
    Loc: Canada
    Posts: 1126, Gallery
    Registered on: Nov 24, 2004
    Reply to: Silver Bullet

    Re: Hesitation and slight loss of Power

    Well it's consistently still doing it today, even after filling up with fresh gas. It hesitates and jerks and the rpm oscillate in normal, sport, and PSM off modes. The problem persists even after some"spirited" driving, and all diagnostic lights on the dash remain off. I also noticed that it does it both during acceleration and with the accelerator all the way out while winding down, though it's less noticeable. It does it throughout the rpm range, though its most noticeable between 3 and 5000 rpm, probably because the torque curve is steepest there.

    I guess I'll bring her in next week. . . .

    Apr 22, 2007 9:53:54 AM

    chuckd
    Newbie
    chuckd
    Loc: CA, USA
    Posts: 42, Gallery
    Registered on: Oct 31, 2005
    Reply to: Silver Bullet

    Re: Hesitation and slight loss of Power

    This happened to my 2006 Carrera S 3 months ago. I was driving home after a long trip of spirited driving, then for no reason, the car started to hesitate and jerk while accelerating.

    I called my service guy at the local Porsche dealer and he mentioned that he's heard of this before, its happened to other customers, and he has no fix for it, other than turning the car off and on.

    He believes its software related, and that Porsche is aware of the problem, but has yet to diagnose it.

    If you search through the rennlist forums, one member there complained so much that Porsche has agreed to install an additional blackbox cpu monitor, so that it can capture the data when it occurs again.

    Anyways, the service guy was right. I turned the car off for the day. When I restarted it the next morning, it was functioning normally again. It hasn't repeated the behavior again since.

    Apr 22, 2007 11:02:05 AM

    TheOldMan
    Co-Pilot
    TheOldMan
    Loc: Montreal, Canada
    Posts: 214, Gallery
    Registered on: Sep 27, 2004
    Reply to: chuckd

    Re: Hesitation and slight loss of Power

    I have wittnesed the extreme jerkiness in an 05 C2S. What I have found that has worked is to engage/disengage the 'sport' mode of the Sport Chrono package. For what ever reason, it fixes the problem until the next time.

    It is difficult to determine the exact circumstances, but there appears to be a corelation with the fuel. Lower octanes ~91 in hot weather make the problem more frequent. Higher octane ~94 appears to reduce the frequency, but not elminate it in 'sport' mode, but does eliminate it in non-sport mode.

    Apr 22, 2007 1:51:08 PM

    Silver Bullet
    Veteran
    Silver Bullet
    Loc: Canada
    Posts: 1126, Gallery
    Registered on: Nov 24, 2004
    Reply to: TheOldMan

    Re: Hesitation and slight loss of Power

    Many have speculated about the fuel, but I don't believe it for a second. It happened while I had 1/2 a tank of 94 octane in mine with no problems on the first half of the tank.

    I "solved" the problem yesterday when I turned PSM off and went into sport mode (which initialy made the problem much worse) and then turned PSM back off and went back to normal mode. As soon as I did that, the hesitation and jerking that had been present for three days on 4 separate drives instantly went away and she ran smooth as ever.

    I tried PSM on/off and sport/normal each individually but it did no good until I combined the two, and then went back to a standard setup with PSM on in normal mode.

    This is clearly a computer glitch in the electronic throttle. My bet is that it does not happen on cars that don't have sport chrono. Probably another great reason to avoid the waste of money that sport chrono is.

    I hope it never happens again.

    PS. a search on this topic at rennlist.com reveals that it seems to be a fairly common problem. There is much discussion of it over there.
     
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