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Hesitation - Stumble Problem. Update


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#1 stv951

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Posted April 14, 2010 - 12:08 AM

Hesitation - Stumble problem. UPDATE

As many many here and in other forums, we are experiencing the famous hesitation problem on two cars

Car 1) 997 carrera 2 6 speed no sport chrono
Stock except from cat by pass pipes
72.000klms 2005MY
Symptom:Hesitation in 2nd gear light throttle up to 2000rpm. Above that works great

Car 2) 997 carrera S 2007 MY 6speed
Sports catalysts
Headers
PSE
Symptom:Hesitation in 2nd gear light throttle up to 2000rpm. Above that works great
Car only has 34.000 klm
On the 997S we have tried the following
New coils, plugs, MAF, Throttle body. Tested with fuel cap open, as well as drove without MAF. Same issue everytime

Anyone has solved this ? Any updates or ideas ?

Thanks
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#2 number9ine

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Posted April 14, 2010 - 06:17 AM

Hesitation - Stumble problem. UPDATE

As many many here and in other forums, we are experiencing the famous hesitation problem on two cars

Car 1) 997 carrera 2 6 speed no sport chrono
Stock except from cat by pass pipes
72.000klms 2005MY
Symptom:Hesitation in 2nd gear light throttle up to 2000rpm. Above that works great

Car 2) 997 carrera S 2007 MY 6speed
Sports catalysts
Headers
PSE
Symptom:Hesitation in 2nd gear light throttle up to 2000rpm. Above that works great
Car only has 34.000 klm
On the 997S we have tried the following
New coils, plugs, MAF, Throttle body. Tested with fuel cap open, as well as drove without MAF. Same issue everytime

Anyone has solved this ? Any updates or ideas ?

Thanks


Do you have the stock cats and headers to replace and test with? This would be my first troubleshooting step. If the stock system still hesitates you know it's not your add-ons.

Has the ECU been remapped? Is the behavior recent or chronic?
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#3 rob545

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Posted April 14, 2010 - 07:52 AM


Hesitation - Stumble problem. UPDATE

As many many here and in other forums, we are experiencing the famous hesitation problem on two cars

Car 1) 997 carrera 2 6 speed no sport chrono
Stock except from cat by pass pipes
72.000klms 2005MY
Symptom:Hesitation in 2nd gear light throttle up to 2000rpm. Above that works great

Car 2) 997 carrera S 2007 MY 6speed
Sports catalysts
Headers
PSE
Symptom:Hesitation in 2nd gear light throttle up to 2000rpm. Above that works great
Car only has 34.000 klm
On the 997S we have tried the following
New coils, plugs, MAF, Throttle body. Tested with fuel cap open, as well as drove without MAF. Same issue everytime

Anyone has solved this ? Any updates or ideas ?

Thanks


Do you have the stock cats and headers to replace and test with? This would be my first troubleshooting step. If the stock system still hesitates you know it's not your add-ons.

Has the ECU been remapped? Is the behavior recent or chronic?


This may sound ridiculously simple, but every few months I begin to detect a slight hesitation in my 997, and I simply add a bottle of Techron fuel system cleaner and by the next tankful it is usually gone or significantly reduced. I suspect these vehciles are quite sensitive to any type of fuel system build up. Aside from that, you may also consider the possibility they have both been fed some poor or contaminated gas. Just a thought. Good luck.
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Robert

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#4 stv951

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Posted April 14, 2010 - 08:03 AM



Hesitation - Stumble problem. UPDATE

As many many here and in other forums, we are experiencing the famous hesitation problem on two cars

Car 1) 997 carrera 2 6 speed no sport chrono
Stock except from cat by pass pipes
72.000klms 2005MY
Symptom:Hesitation in 2nd gear light throttle up to 2000rpm. Above that works great

Car 2) 997 carrera S 2007 MY 6speed
Sports catalysts
Headers
PSE
Symptom:Hesitation in 2nd gear light throttle up to 2000rpm. Above that works great
Car only has 34.000 klm
On the 997S we have tried the following
New coils, plugs, MAF, Throttle body. Tested with fuel cap open, as well as drove without MAF. Same issue everytime

Anyone has solved this ? Any updates or ideas ?

Thanks


Do you have the stock cats and headers to replace and test with? This would be my first troubleshooting step. If the stock system still hesitates you know it's not your add-ons.

Has the ECU been remapped? Is the behavior recent or chronic?


This may sound ridiculously simple, but every few months I begin to detect a slight hesitation in my 997, and I simply add a bottle of Techron fuel system cleaner and by the next tankful it is usually gone or significantly reduced. I suspect these vehciles are quite sensitive to any type of fuel system build up. Aside from that, you may also consider the possibility they have both been fed some poor or contaminated gas. Just a thought. Good luck.

I have tried and tested many types of super plus unleaded fuel. The problem is only at very low revs, above that (2000 rpm) the car is very fast
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#5 rob545

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Posted April 14, 2010 - 10:43 AM




Hesitation - Stumble problem. UPDATE

As many many here and in other forums, we are experiencing the famous hesitation problem on two cars

Car 1) 997 carrera 2 6 speed no sport chrono
Stock except from cat by pass pipes
72.000klms 2005MY
Symptom:Hesitation in 2nd gear light throttle up to 2000rpm. Above that works great

Car 2) 997 carrera S 2007 MY 6speed
Sports catalysts
Headers
PSE
Symptom:Hesitation in 2nd gear light throttle up to 2000rpm. Above that works great
Car only has 34.000 klm
On the 997S we have tried the following
New coils, plugs, MAF, Throttle body. Tested with fuel cap open, as well as drove without MAF. Same issue everytime

Anyone has solved this ? Any updates or ideas ?

Thanks


Do you have the stock cats and headers to replace and test with? This would be my first troubleshooting step. If the stock system still hesitates you know it's not your add-ons.

Has the ECU been remapped? Is the behavior recent or chronic?


This may sound ridiculously simple, but every few months I begin to detect a slight hesitation in my 997, and I simply add a bottle of Techron fuel system cleaner and by the next tankful it is usually gone or significantly reduced. I suspect these vehciles are quite sensitive to any type of fuel system build up. Aside from that, you may also consider the possibility they have both been fed some poor or contaminated gas. Just a thought. Good luck.

I have tried and tested many types of super plus unleaded fuel. The problem is only at very low revs, above that (2000 rpm) the car is very fast

I understand. Just think that a bottle of detergeant is fairly cheap diagnosis if it changes anything. My experience has been that when it needs the treatment, it is most evident under low RPM conditions, it has never affected the power once things get flowing. I think proper metering is critical at the lower revs and as power builds so does the tolerance with any inconsistency in fuel delivery.
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Robert

997 Cab
H&R Springs
COR Wheels

#6 wvicary

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Posted April 14, 2010 - 04:15 PM

I agree with installing the OEM parts and retesting. You need to establish a base line for testing.


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#7 355bhp

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Posted April 14, 2010 - 07:49 PM


Symptom:Hesitation in 2nd gear light throttle up to 2000rpm. Above that works great

Have you tried the good ol' fashioned "Italian tune-up"? Take them out and run 'em up near the redline making as much noise as you can, and hold it there a bit. Mine likes that sort of thing, and they all were designed for it. Personally, I stay away from 2000 rpm and a light throttle as much as possible.
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Rick

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#8 utkinpol

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Posted April 15, 2010 - 06:28 AM


Symptom:Hesitation in 2nd gear light throttle up to 2000rpm. Above that works great

Have you tried the good ol' fashioned "Italian tune-up"? Take them out and run 'em up near the redline making as much noise as you can, and hold it there a bit. Mine likes that sort of thing, and they all were designed for it. Personally, I stay away from 2000 rpm and a light throttle as much as possible.


I run fabspeed x-pipe with 200cell cats and had fabspeed maxflo mufflers - now instead of maxflos I reverted back to stock mufflers to reduce noise - so with stock mufflers hesitation _almost_ never happens.
When ECU tunes timing way up high to start this hesitation again I simply disconnect battery so it re-tunes itself and hesitation disappears. Difficult to say what conditions do tune ECU into this problem but it is reversible and I think it is simply a feature - not a bug, if you have system pushed closer to free flow exhaust - you gain a lot of pull in top RPM area but get those oddities in 1K-2K rpm section.
Just learn not to give full throttle right after dropping rpms from 4K-5K back to 1K while on second gear. That is when it happens, so, just blip it gently half throttle until you get into 2K and then give full throttle.

Edited by utkinpol, April 15, 2010 - 06:29 AM.

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#9 355bhp

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Posted April 17, 2010 - 10:47 AM

I run fabspeed x-pipe with 200cell cats and had fabspeed maxflo mufflers - now instead of maxflos I reverted back to stock mufflers to reduce noise - so with stock mufflers hesitation _almost_ never happens.

Yup, mine's a stock set-up, and I don't ever recall the low-rpm stumble problem. I've mentioned this before, but I think there's a coupla loose baffles in the muffler that wakes up sleepy Highway Patrol officers, but I love the sound, especially when winding it up to 6 or 7K revs through a canyon with the windows down and sunroof open!
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Rick

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#10 dphatch

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Posted April 18, 2010 - 01:49 PM

Disconnect the negative battery terminal for awhile to reset the computer. Some say 10 minutes, others say 3 hours. I suspect 30 minutes is more than ample time to wait before rebooting the cars computer which is what you're doing. Porsche board wisdom is that the computer sets the throttle map according to the way you drive the car. So if you're mainly driving in town stop and go it dumbs down the throttle map resulting in hesitation. It definitely won't hurt the car to disconnect the battery. You'll get a PSM fault code when you start the car after the reconnecting the battery but it will go way in about 30 seconds after you drive off. I have also heard this problem is a function of the electronic throttle itself. Have seen a write up for an after market gadget that claims to eliminate this hesitation by changing the electronic signal to the engine. Thought I saved the link but can not find it.Will post it if I can find it.


Edited by dphatch, April 18, 2010 - 01:50 PM.

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#11 utkinpol

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Posted April 19, 2010 - 08:19 AM

Disconnect the negative battery terminal for awhile to reset the computer. Some say 10 minutes, others say 3 hours. I suspect 30 minutes is more than ample time to wait


Actually 2 minutes is enough but wait for 10.
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#12 dphatch

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Posted April 20, 2010 - 03:27 PM

OK. Found the item I refered to in my earlier email. It's called Sprint Booster and attaches between the e-gas peddle and the cable that's attached to it. Supposed to eliminate the lag much like the Sport Chrono does but without remappng the throttle itself. SprintboosterUSA.com is the link. I have no idea if it works or not and being the worlds biggest sceptic, it sounds like snake oil to me. But if you wanted to try it and let us all know if it worked that would be great. I know I'd be anxious to hear what you think. Check out the link below if you want to read what one guy wrote concerning the Sprint Booster. http://www.peony888....rintBooster.pdf


Edited by dphatch, April 20, 2010 - 03:52 PM.

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#13 WTL

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Posted April 21, 2010 - 07:04 AM

I complained to my dealer awhile back about a "blip" or hesitation around 2,000rpm under light driving. Upon accelerating, rpm's going up, then a brief noticeable minor dip, then all good and normal. It's been awhile so I don't remember all the reasons they gave me in telling me it's normal. Something to do with the way the engine is mapped, cam timing, for increased fuel economy....


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#14 deschodt

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Posted June 14, 2010 - 11:56 AM

OK. Found the item I refered to in my earlier email. It's called Sprint Booster and attaches between the e-gas peddle and the cable that's attached to it. Supposed to eliminate the lag much like the Sport Chrono does but without remappng the throttle itself. SprintboosterUSA.com is the link. I have no idea if it works or not and being the worlds biggest sceptic, it sounds like snake oil to me. But if you wanted to try it and let us all know if it worked that would be great. I know I'd be anxious to hear what you think. Check out the link below if you want to read what one guy wrote concerning the Sprint Booster. http://www.peony888....rintBooster.pdf


Not snake oil at all, but it does not work quite as you describe... The new model has 3 positions
Off: It does nothing
Green: 50%: no more lag, but it does remap the throttle signal to something like sports chrono
Red: 100% : no more lag, even more aggressive map. Too aggressive and binary for me....

It translates the pedal signal on the fly. There is no denying it does what it says it does.... It's only useful for those of us who didn't get Sports chrono or hate the lag, or both. I love mine...
I hated the original one (one mode), but the 3 modes on is perfect at 50% !
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#15 Dus10R

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Posted August 21, 2012 - 09:08 AM

I think the common denominator is aftermarket exhaust... I bought a Carrera S with full AWE exhaust system and mine does it too. Pretty bad sometimes... From 1500- 2000 rpm and it feels like a turbo with bad spark plugs. Its heart skips a beat and then she's good to go. I drive around it, but it sucks that I have to. And if someone else drives it I have to tell them not to juice it from way down low or if they do then I have to explain that its normal...lame. I need to run some Durametric logs and see what actually happens...check AFR's, Throttle, Cam Position, etc... But this post is old, anyone able to figure this one out in the past two years?


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#16 active 997

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Posted January 30, 2014 - 03:58 AM

I have exactly the same problem. Hesitate at low revs. My local service shop said that i need to replace the fuel injectors.?!?


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#17 Dus10R

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Posted February 01, 2014 - 11:00 AM

Anyone else notice a rich smell at low rpms? I have a feeling that this hesitation may be an over rich condition when going close to WOT from low RPM's. May need a custom tune to fix or ive heard of some guys installing O2 sensor spacers? Anybody try it?


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#18 garrarni

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Posted February 02, 2014 - 01:26 AM

i tried an aftermarket exhaust for a while - 200cell ports x-pipe & mufflers - and got a bad hesitation at low revs, similar to that described.  took the x-pipe off and put the OEM cats back on and all good.  found that the x-pipe would be great for track type use, but really spoiled the car as a daily driver.


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#19 jl-c

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Posted February 02, 2014 - 06:30 AM

i tried an aftermarket exhaust for a while - 200cell ports x-pipe & mufflers - and got a bad hesitation at low revs, similar to that described.  took the x-pipe off and put the OEM cats back on and all good.  found that the x-pipe would be great for track type use, but really spoiled the car as a daily driver.


+ 1 for this!
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#20 Dus10R

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Posted June 02, 2014 - 06:55 PM

Just plugged in my Durametric to try and snag a AFR like I used to do with my 996TT and....there's no parameter to log. Or if there is I haven't the slightest idea what it's called or how to convert it to AFR . Anybody have any ideas? 2006 Carrera S...


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