slight hesitation on accel at 3k rpm (991 base, MT)
03-26-2014, 12:46 AM
#31
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I have a 2013 C4S PDK and have the same issue. It really felt as if the engine hard a hard time breathing around 2,800 rpm. Now my car is run in, and after a software update from the dealer, the problem is significantly less. Originally it felt awful, now it's far, far less noticeable.
I think it's fuel mixture (which is maybe why it appears less on cold engines) coupled with variocam engagement and poor tuning biased towards emissions. Maybe they are trying to run 'closed loop' with the O2 sensors on partial throttle and just can't achieve a smooth engine with variocam in this mode....?
Andy
I think it's fuel mixture (which is maybe why it appears less on cold engines) coupled with variocam engagement and poor tuning biased towards emissions. Maybe they are trying to run 'closed loop' with the O2 sensors on partial throttle and just can't achieve a smooth engine with variocam in this mode....?
Andy
04-20-2015, 08:53 AM
#32
Rennlist Member
I have a 2012 997.2 C4S and it has been doing the stumbling/hesitation at around 3k rpm since I bought it.
The simple procedure outlined below has eliminated the problem for me almost completely.
As you all know, the car starts the auto idle procedure when its been parked for several hours (which is usually the case in the morning when the car is started for the first time that day) and the revs go to approximately 1,500 rpm for about 1 minute. When this happens, I immediately blip the gas and take the revs to between 3-4k rpm. This will deactivate the auto idle and the revs will fall to its normal level of 800-850.
Thats it. This procedure will keep your car stumble free as long as the auto idle is not allowed to engage.
Please give a try and give your feedback
The simple procedure outlined below has eliminated the problem for me almost completely.
As you all know, the car starts the auto idle procedure when its been parked for several hours (which is usually the case in the morning when the car is started for the first time that day) and the revs go to approximately 1,500 rpm for about 1 minute. When this happens, I immediately blip the gas and take the revs to between 3-4k rpm. This will deactivate the auto idle and the revs will fall to its normal level of 800-850.
Thats it. This procedure will keep your car stumble free as long as the auto idle is not allowed to engage.
Please give a try and give your feedback
04-20-2015, 11:20 AM
#33
Rennlist Member
Found this thread after a Google search, trying to find any help on this engine condition, stumble, misfire thing. THIS procedure actually works!! I can still barely feel a little something when the tach sweeps past 2800 but NOTHING like before! I was to read point it was really bugging the **** out of me! For whatever reason this definitely has helped if not almost completely eliminated the issue for me. I find it doesn't take that much of a rev to kick the idle down, anything close to 3k will knock it down. Give it a try.
WOW I have to conscientiously try this and then pay attention to the car. It bugs me from time to time and when I feel it I usually downshift for a few minutes and it goes away. 13 C4S PDK
04-20-2015, 11:46 AM
#34
Rennlist Member
Mine a manual, 997.2. It can really jack with you when driving more mellow, like in traffic. Seem that 2nd gear shift rpm lands right in that 2500 range, you get on the gas a little and it falls on it's face and bucks the car. Ridiculous a company like Porsche can't figure this out. My buddys 996 GT3 pulls away as smooth and easy as a honda civic compared to my car!
04-20-2015, 12:32 PM
#35
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Take it to the track or hard drive on the back roads keep rpm above 4k for at least 4 to 5 minutes then go for engin flush and oil change.
That fixed the histation on my 997.2p
These cars are designed to be driven hard
That fixed the histation on my 997.2p
These cars are designed to be driven hard
04-20-2015, 12:38 PM
#36
Rennlist Member
You're preaching to the choir. My car rarely sees rpm below 4k regardless. Has nothing to do with an Italian tune up or oil change. This is a mapping issue with the cars.
08-20-2015, 03:04 AM
#38
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Blips and hesitation at 31-3300 rpm
Wheeler...that is on egorgeous auto you have there...do tell me what it is...duck tail? No emblems...awesome.
I have an 02 c4S that does this. Going to try that little start her up trick.
I have also heard that aftermarket exhaust and cats and such will make this issue even more noticeable. My tuner tells me that a good zoom in on the curve at those rims can smooth out...I have yet to try this...sure would like to "borrow " somebody's cable and software and re-tune my engine...bought it with fvd stage 2 on it and I can't touch it without paying another 850-1000 to buy a new tune kit...
Anyway...folks are in MCI area... Ex 930 operator and current Macan guy ... That's mi dad...me, only 911.
Pb
I have an 02 c4S that does this. Going to try that little start her up trick.
I have also heard that aftermarket exhaust and cats and such will make this issue even more noticeable. My tuner tells me that a good zoom in on the curve at those rims can smooth out...I have yet to try this...sure would like to "borrow " somebody's cable and software and re-tune my engine...bought it with fvd stage 2 on it and I can't touch it without paying another 850-1000 to buy a new tune kit...
Anyway...folks are in MCI area... Ex 930 operator and current Macan guy ... That's mi dad...me, only 911.
Pb
08-20-2015, 09:19 AM
#39
Rennlist Member
Thanks man, 09 C2S, pasm, lowered on H&R springs. Getty sport duck tail. Love it!
Wheeler...that is on egorgeous auto you have there...do tell me what it is...duck tail? No emblems...awesome.
I have an 02 c4S that does this. Going to try that little start her up trick.
I have also heard that aftermarket exhaust and cats and such will make this issue even more noticeable. My tuner tells me that a good zoom in on the curve at those rims can smooth out...I have yet to try this...sure would like to "borrow " somebody's cable and software and re-tune my engine...bought it with fvd stage 2 on it and I can't touch it without paying another 850-1000 to buy a new tune kit...
Anyway...folks are in MCI area... Ex 930 operator and current Macan guy ... That's mi dad...me, only 911.
Pb
I have an 02 c4S that does this. Going to try that little start her up trick.
I have also heard that aftermarket exhaust and cats and such will make this issue even more noticeable. My tuner tells me that a good zoom in on the curve at those rims can smooth out...I have yet to try this...sure would like to "borrow " somebody's cable and software and re-tune my engine...bought it with fvd stage 2 on it and I can't touch it without paying another 850-1000 to buy a new tune kit...
Anyway...folks are in MCI area... Ex 930 operator and current Macan guy ... That's mi dad...me, only 911.
Pb
08-22-2015, 07:27 PM
#40
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tried the start up thi8ng
did not work for me...well...maybe it did, but not all the way gone...I could not get the auto idle to disengage and I thought I timed it perfect...did it several times to try to get it to disengage, but I don't know that I did it successfully...
I think it is just a fact of life on some cars and not on others. Also more noticable on aftermarket exhaust...
My neighbors likely hate me for my early morning throttling to get that auto idle up to come down...
pb
I think it is just a fact of life on some cars and not on others. Also more noticable on aftermarket exhaust...
My neighbors likely hate me for my early morning throttling to get that auto idle up to come down...
pb
08-11-2019, 10:20 AM
#41
Instructor
Hello everyone,
I have experienced the same on my 2011 C4S (27K miles) - the hesitation/stumble is now less evident after I changed battery (OEM, and changed at the dealership). But still, between 2500 and 3000 I can feel a little stumble.
Does anyone have an update on this annoying problem?
Ric
I have experienced the same on my 2011 C4S (27K miles) - the hesitation/stumble is now less evident after I changed battery (OEM, and changed at the dealership). But still, between 2500 and 3000 I can feel a little stumble.
Does anyone have an update on this annoying problem?
Ric
08-11-2019, 11:20 AM
#42
Rennlist Member
Hi guys,
I've been enjoying my 991 base 7 speed MT for 2 months now, coming out of a 997.1S cabriolet.
I love everything about it, and have reviewed here previously why. Except I'm now noticing just 1 tiny thing, and it is starting to bother me.
In 1st gear, usually only upon the first 10min after a cold start in the morning, upon about 30% throttle (so not gentle, but not WOT either), right at 2900 to 3200 rpm, I get a slight hesitation. As if the fuel was just ever so slightly tapered back. Just a little tiny bit. But I notice it every morning. And it's always right in that rpm range. Happens both in sport mode on/off and sports exhaust on/off (all 4 combos). Now, if I go WOT, it seems to be less noticeable, but it's still there. And when warm, much less noticeable, but still there or I'm thinking it's still there.
I'm right on the edge of just bringing it in to the dealer but would rather put up with it till my 5k service (at 2k now).
What do you guys think? Mass airflow sensor? O2 sensor? (are they the same?) If so, I'm wondering if its ok to just put up with it or if other folks have noticed in either 991's or 997's that it got worse over time and I should really just bring it in?
Thanks in advance.
Jester
I've been enjoying my 991 base 7 speed MT for 2 months now, coming out of a 997.1S cabriolet.
I love everything about it, and have reviewed here previously why. Except I'm now noticing just 1 tiny thing, and it is starting to bother me.
In 1st gear, usually only upon the first 10min after a cold start in the morning, upon about 30% throttle (so not gentle, but not WOT either), right at 2900 to 3200 rpm, I get a slight hesitation. As if the fuel was just ever so slightly tapered back. Just a little tiny bit. But I notice it every morning. And it's always right in that rpm range. Happens both in sport mode on/off and sports exhaust on/off (all 4 combos). Now, if I go WOT, it seems to be less noticeable, but it's still there. And when warm, much less noticeable, but still there or I'm thinking it's still there.
I'm right on the edge of just bringing it in to the dealer but would rather put up with it till my 5k service (at 2k now).
What do you guys think? Mass airflow sensor? O2 sensor? (are they the same?) If so, I'm wondering if its ok to just put up with it or if other folks have noticed in either 991's or 997's that it got worse over time and I should really just bring it in?
Thanks in advance.
Jester
See the C&D link and the hp and torque curves for the 981 vs 718.
https://www.caranddriver.com/reviews...l-test-review/
07-25-2021, 06:00 PM
#43
Hoping to revitalize the older post and see if anyone resolved this issue. I have a 991.1 C2S and since installing the Fabspeed 2nd muffler delete exhaust I noticed the exact issue described in this post. Initially thinking it was MAFS but curious if anyone tried an aftermarket ECU re-map (COBBS, Softronic?).
07-25-2021, 11:09 PM
#45
Instructor
as a matter of fact I have an update. Few weeks ago I have changed the plug sparks and the ignition coils and now the dip at 2800/3000 looks gone. I says looks, because I haven't driven the car enough after this maintenance work.
One thing mentioned by my indy Porsche mechanic is that the plug sparks previously installed were OEM but not the right one for the model of my car: they had a lower temperature tolerance then the one required by my car (997.2 C4S). For the record my car was a 2011 CPO with 26K miles when I bought it.
Moreover, in his opinion the hesitation was probably a misfire due to a bad spark plug or ignition coil.
Riccardo
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