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Quick survey: "Hesitation" problem

 
Old 10-20-2006, 06:11 PM
  #31  
Tony356993
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200 miles and the throttle body alignment seems to have fixed the problem. we will see.
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Old 10-22-2006, 07:32 PM
  #32  
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i had it happen once at 4000 miles less than 1/2 tank, spirited driving followed by 45 mph for 1/2 hour, stopped for ten minutes turned off car. (cool weather) and it hesitated bucked and kicked, went to wot and no problem.
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Old 10-22-2006, 08:53 PM
  #33  
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Originally Posted by clif
i had it happen once at 4000 miles less than 1/2 tank, spirited driving followed by 45 mph for 1/2 hour, stopped for ten minutes turned off car. (cool weather) and it hesitated bucked and kicked, went to wot and no problem.
What is your model and year?
 
Old 11-07-2006, 12:49 AM
  #34  
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Originally Posted by dstrimbu
Tony, I heard that anything over 94-95 octane in a stock 997 will cause idle issues. Something to do with fuel mapping / emissions.

I read it here... don't remember the post, sorry.

Betcha Ben can find it. ;-)

-don
Was it this one, Don?

https://rennlist.com/forums/showpost...7&postcount=12
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Old 11-10-2006, 11:14 PM
  #35  
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I have experienced this as well. both in "stock" form when I first purchased the car and after my "bolt on" upgrades. I have run 91 & 100 octane, I can not put my finger on anything that seems to aggrivate the problem. I would say it has happened 6 times or so... dealer is clueless to my description. Feels like a car running out of gas...
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Old 11-10-2006, 11:23 PM
  #36  
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Guy's:

Had the exact same symptoms with my 2006 E55, it turned out to be a loose connection in/to the fuel pump. BTW, quite a few E55's also suffered from the hesitation issue and with no check engine or malfuntion codes. The reason the dealership found where the hesitation was coming from is the last time it occurred, the car completely stalled and would not restart and had to be towed to the dealership. Once at the dealership the car still would not start and that's how they finally traced the problem. The issue occurred twice in the first 1500 miles.
 
Old 01-20-2018, 02:38 PM
  #37  
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Originally Posted by Coochas View Post
There are MANY threads on this subject on Rennlist as well as the 'other' p-car fora (forums?).
I think a good summary is that:
1) It happens on an idiosyncratic basis.
2) It doesn't necessarily happen again.
3) Some people can temporally correlate it with changing gas brands.
4) Some believe it is a "vapor lock" like phenomenon reporting variable efficacy associated with venting the gas cap with the car running.
5) Regardless of the cause, it appears to be self-correcting in almost all reported cases.
6) There is no one single explanation of its cause.

My personal experience was after filling the tank with a different brand of gas. Car hesitated at constant rpm and was gone with wide open throttle. Gas cap trick did not fix it. It went away by itself after about 15 minutes. This happened once and has not returned in over 1500 miles since.

It would be great if someone with an OBDII probe could analyze the car WHILE it's happening. Anyone keeping an OBD tester in the glove box?
Interesting report.
What is the gas cap trick ?
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Old 01-20-2018, 02:54 PM
  #38  
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Originally Posted by 911searcher View Post
Interesting report.
What is the gas cap trick ?
That was just referring to opening the gas cap to equalize any potential pressure difference.
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Old 01-20-2018, 03:02 PM
  #39  
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Originally Posted by Coochas View Post
That was just referring to opening the gas cap to equalize any potential pressure difference.
Makes sense.
Thanks.
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Old 02-26-2018, 04:23 PM
  #40  
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Default Old topic fuel hesitation revisited

New to this Porsche 997 forum and been reading up on ‘Hesitations’, bucking etc. My recently acquired 2006 Cab S with the 1st gen 997/manual has had a few similar instances! I wouldn’t call them hesitations’, more like total fuel starvation. Two times in 1st gear starting out and once on the highway cruising along around 75mph.
On the 1st gear starts, had to pull (coast over) and just restart vehicle, then no problem for the rest of the trip(s). On the highway instance, felt loss of all power, started to pull over, and then felt engine kick over like getting a push start. Again remaining trip OK.

In all three occurrences’, no miss fire, sputtering, nothing. And like many other reports, no codes, check engine light etc. So from a lot of experience with older carburetor/mechanical fuel pump cars, all three recent incidences reminded me of simple fuel starvation! BTW, these occurrences’ happened on different fuel fill ups and at different stations.

So start investigating (Porsche essiential companion)and first thing I find out is the fuel pump, fuel pressure regulator and fuel filter (non replacement) are all integrated inside the fuel tank. Plus there is a carbon canister filter. Mechanical wise, the fuel delivery system sounds a bit more complicated than just replacing an external component.

But then with any modern vehicle, one also has to consider the electronic control side. Fuel demand (injectors) /delivery and the venting controlled by the ECU (DME). Also, there is a tank leakage diagnostics module (DM-TL) in the loop somewhere?
Bottom line, electromechanical system diagnostics (especially intermittent problems) can be a real PIA so I’m moving forward cautiously! Any input appreciated,

Thanks

Rick
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Old 02-26-2018, 04:56 PM
  #41  
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Originally Posted by rick500 View Post
New to this Porsche 997 forum and been reading up on ‘Hesitations’, bucking etc. My recently acquired 2006 Cab S with the 1st gen 997/manual has had a few similar instances! I wouldn’t call them hesitations’, more like total fuel starvation. Two times in 1st gear starting out and once on the highway cruising along around 75mph.
On the 1st gear starts, had to pull (coast over) and just restart vehicle, then no problem for the rest of the trip(s). On the highway instance, felt loss of all power, started to pull over, and then felt engine kick over like getting a push start. Again remaining trip OK.

In all three occurrences’, no miss fire, sputtering, nothing. And like many other reports, no codes, check engine light etc. So from a lot of experience with older carburetor/mechanical fuel pump cars, all three recent incidences reminded me of simple fuel starvation! BTW, these occurrences’ happened on different fuel fill ups and at different stations.

So start investigating (Porsche essiential companion)and first thing I find out is the fuel pump, fuel pressure regulator and fuel filter (non replacement) are all integrated inside the fuel tank. Plus there is a carbon canister filter. Mechanical wise, the fuel delivery system sounds a bit more complicated than just replacing an external component.

But then with any modern vehicle, one also has to consider the electronic control side. Fuel demand (injectors) /delivery and the venting controlled by the ECU (DME). Also, there is a tank leakage diagnostics module (DM-TL) in the loop somewhere?
Bottom line, electromechanical system diagnostics (especially intermittent problems) can be a real PIA so I’m moving forward cautiously! Any input appreciated,

Thanks

Rick
I just commented on a similar misfire in this thread:
https://rennlist.com/forums/997-foru...l#post14831287

Simplest thing I would check is your gas cap. There are a bunch of posts on the gas cap seal going bad, or the cap not being tightened properly, leading to a misfire / bucking. In my service records the prior owner replaced my cap a few years ago after a CEL. I had an issue the other day of the car surging/bucking due to my cap not being properly tightened.
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Old 02-26-2018, 11:40 PM
  #42  
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Good point and SIMPLE too! While I always check securing the gas cap have not thought about a possible bad seal? Thanks
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Old 02-28-2018, 04:33 AM
  #43  
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Originally Posted by CharlieJr View Post
I've read in a number of places that some 997 owners are complaining about an engine hesitation problem.

Is this a wide-spread issue, or just limited to a few occurrences? Was it limited to a production time period? Tip vs. stick? Is it based on fuel (ethanol, etc.), or location?

One of the attractions of Porshe is the quality, and if I spend ~$100k I expect a reliable car. In this thread I'm not so much interested in potential technical fixes, but if this is an issue I should be concerend about at all.

FYI - I tested a Cayenne, and it hesitated badly as I was making a left turn across oncoming traffic, but I thought it was me - - until I started reading these 997 forums.

Don't mean to raise a potential non-problem here, but thought current owners could help out some future ones. thanks
I have a hesitation at the beginning of driving. It's really annoying in traffic jams.
The hesitation exists both in first and second gear (TIP S) between 1500-2500 RPM. Even when the engine is cold and when the engine is hot. The RPM "jumps" really feel a blow in the back.
From what I have read, I noticed that hesitation exists in TIP, MT and PDK. But, I still have not found a solution (mystery)
I'd love to hear if anyone has a solution ..[No lights came on, no warning of any kind. No fault codes were registered.]
I realized that it could come from an MAF sensor and could be cleaned with white gas. what do you think?
Feeling desperate ..
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Old 03-01-2018, 03:22 PM
  #44  
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Yeah I'm having it too, a very minor hesitation between 1500 rpm and 2500 rpm. Any consensus yet?
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Old 05-08-2018, 02:23 PM
  #45  
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997.1 S (like mine) has the traction control module, my experience with that was like you , traveling at fwy speeds + a little more, went over a pretty uneven portion of the road, and the cars reactions were to decelerate lightly apply some braking, and when slowed a bit and all was good it gave me back control of the vehicle...
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