997.1 Carrera - hesitates at low rpm
07-17-2021, 01:09 AM
#196
Exhaust
I got hesitation from the exhaust after adding an x-pipe as well whether I had a tune or not.
Beyond the hesitation you might also be feeling the big dip that I've seen in the power curve from other people's dynos and my seat of the pants feel from blending (x-pipe) the exhaust gasses since the car wasn't designed for it. If you auto-x then remember to keep the engine spinning as fast as possible otherwise the car will feel like a dog down low in anything but 1st gear.
If you want a broader and more usable power curve you'll have to go back to a stock style exhaust that doesn't blend each bank of the engine.
This is the opinion of someone who is most definitely not an expert...
The exhaust I only keep for the sound because it's not my daily beater so I don't care that it's killed my bottom end power.
Beyond the hesitation you might also be feeling the big dip that I've seen in the power curve from other people's dynos and my seat of the pants feel from blending (x-pipe) the exhaust gasses since the car wasn't designed for it. If you auto-x then remember to keep the engine spinning as fast as possible otherwise the car will feel like a dog down low in anything but 1st gear.
If you want a broader and more usable power curve you'll have to go back to a stock style exhaust that doesn't blend each bank of the engine.
This is the opinion of someone who is most definitely not an expert...
The exhaust I only keep for the sound because it's not my daily beater so I don't care that it's killed my bottom end power.
Last edited by flomofo; 07-17-2021 at 01:10 AM.
12-18-2023, 03:30 PM
#197
Track Day
All stock
Hi guys, I'm experiencing the exact same issue, low RPM on throttle hesitation or stutter. Once the revs get over about 1200 all is well. Its a manual, i just bought the car August 2023 and haven't driven stick in years. It did not have this issue until about 2 months after I got it. No CEL on, cam deviations are below 1deg, rough running values are below 1 with an occasional spike to 1.5 and no misfires detected. All measurements at idle.
Since my ownership I have done the following maintenance:
Date KM
Aug-23 165000 Purchased car
Aug-23 165250 CEL on for code P0491 and P0492 (insufficient SAI flow)
Aug-23 165550 Cleaned air box
Aug-23 166000 New air filter
Sep-23 166125 Repaired driver door lock cylinder
Sept 8 2023 166500 Manometer tested crankcase at 5.25 @ 800 rpm
Sept 20 2023 167000 Brake pads all around
Sept 30 2023 167250 Installed PCCM
Oct 7 2023 167500 Oil change, installed magnetic drain plug, spin on adapter, scoped bores through plug holes - clean at the tops, changed spark plugs
Oct 19 2023 168650 Noticed an unusual hesitation, low RPM under load, intermittent
Oct 30 2023 168721 Purchased winter rims and tires
Nov 6 2023 168880 Cleaned throttle body
Nov 20 2023 168950 Installed Winter rims and tires
Dec 15 2023 169735 Installed oem motor mounts, connected +ve lead for SAI pump, cleaned and lubriacted SAI check valve, found loose bolt for oil filler tube, tightened, changed gas cap o ring, CEL off
Here is what I have tried from a list on another thread
1) Italian tune up: Take it out and blast it at 6+k for a while.
This really helped temporarily. After a good run it ran much better with less hesitation and less frequently but was back to more frequent when driving next a few days later
2) Try running in Sport (if equipped) to see if it hesitates in that mode.
No difference
3) Computer/throttle map reset via battery disconnect for 30 minutes.
No difference
4) Try Techron fuel additive.
After watching the Jake Raby video about additives I think I'll give seafoam a try before my next oil change
5) Run ethanol-free gas a few times with Heet gas treatment.
Will try this next time I can make to the closest station an hour away
6) Open gas cap, start engine, idle for a while, stop, re-close cap.
No difference, I did change my gas cap o ring recently
7) Same as above except for oil fill cap.
The idle goes way off and runs rough
8) Look for vacuum leaks in hoses.
When I was in there to diagnose the SAI CEL all the vacuum lines looked good and since my manometer test was in spec I think I'm good here but I have the parts ready to make a smoke machine and will get to this eventually.
9) The Oil vent hose could have a vacuum leak.
No checked
10) Transmission fluid could be low.
It manual and the fluid is scheduled to be changed in the spring
11) Fuel filter needs changing.
I believe this is in the tank, I haven't looked into it yet
12) Fuel pump is malfunctioning.
I was considering putting a fuel pressure gauge in to check, has anyone done this? What pressure would I expect?
13 Automatic Transmission Filter needs changing.
N/A
14) Automatic Transmission Fluid needs changing.
N/A
15) Catalytic converter clogged.
How can I check this?
16) Throttle plate sticking.
I cleaned the throttle body and watched it operation when I put the battery back on and it appeared to move freely to me. Is there another way to test?
17) Vacuum leak.
See above
18) Oil vent hose causing a vacuum leak.
Where is the oil vent hose?
19) Wait until it goes away.
Wouldn't that be nice
20) Stop accidentally touching the Tiptronic controls by using proper grip.
N/A
21) It's a software issue, and we'll never have a solution until Porsche admits it is happening.
N/A
Any help, ideas, comments or opinions would be great!
Steve
2007 C4
Since my ownership I have done the following maintenance:
Date KM
Aug-23 165000 Purchased car
Aug-23 165250 CEL on for code P0491 and P0492 (insufficient SAI flow)
Aug-23 165550 Cleaned air box
Aug-23 166000 New air filter
Sep-23 166125 Repaired driver door lock cylinder
Sept 8 2023 166500 Manometer tested crankcase at 5.25 @ 800 rpm
Sept 20 2023 167000 Brake pads all around
Sept 30 2023 167250 Installed PCCM
Oct 7 2023 167500 Oil change, installed magnetic drain plug, spin on adapter, scoped bores through plug holes - clean at the tops, changed spark plugs
Oct 19 2023 168650 Noticed an unusual hesitation, low RPM under load, intermittent
Oct 30 2023 168721 Purchased winter rims and tires
Nov 6 2023 168880 Cleaned throttle body
Nov 20 2023 168950 Installed Winter rims and tires
Dec 15 2023 169735 Installed oem motor mounts, connected +ve lead for SAI pump, cleaned and lubriacted SAI check valve, found loose bolt for oil filler tube, tightened, changed gas cap o ring, CEL off
Here is what I have tried from a list on another thread
1) Italian tune up: Take it out and blast it at 6+k for a while.
This really helped temporarily. After a good run it ran much better with less hesitation and less frequently but was back to more frequent when driving next a few days later
2) Try running in Sport (if equipped) to see if it hesitates in that mode.
No difference
3) Computer/throttle map reset via battery disconnect for 30 minutes.
No difference
4) Try Techron fuel additive.
After watching the Jake Raby video about additives I think I'll give seafoam a try before my next oil change
5) Run ethanol-free gas a few times with Heet gas treatment.
Will try this next time I can make to the closest station an hour away
6) Open gas cap, start engine, idle for a while, stop, re-close cap.
No difference, I did change my gas cap o ring recently
7) Same as above except for oil fill cap.
The idle goes way off and runs rough
8) Look for vacuum leaks in hoses.
When I was in there to diagnose the SAI CEL all the vacuum lines looked good and since my manometer test was in spec I think I'm good here but I have the parts ready to make a smoke machine and will get to this eventually.
9) The Oil vent hose could have a vacuum leak.
No checked
10) Transmission fluid could be low.
It manual and the fluid is scheduled to be changed in the spring
11) Fuel filter needs changing.
I believe this is in the tank, I haven't looked into it yet
12) Fuel pump is malfunctioning.
I was considering putting a fuel pressure gauge in to check, has anyone done this? What pressure would I expect?
13 Automatic Transmission Filter needs changing.
N/A
14) Automatic Transmission Fluid needs changing.
N/A
15) Catalytic converter clogged.
How can I check this?
16) Throttle plate sticking.
I cleaned the throttle body and watched it operation when I put the battery back on and it appeared to move freely to me. Is there another way to test?
17) Vacuum leak.
See above
18) Oil vent hose causing a vacuum leak.
Where is the oil vent hose?
19) Wait until it goes away.
Wouldn't that be nice
20) Stop accidentally touching the Tiptronic controls by using proper grip.
N/A
21) It's a software issue, and we'll never have a solution until Porsche admits it is happening.
N/A
Any help, ideas, comments or opinions would be great!
Steve
2007 C4
12-18-2023, 04:01 PM
#198
RL Community Team
Rennlist Member
Rennlist Member
Hi guys, I'm experiencing the exact same issue, low RPM on throttle hesitation or stutter. Once the revs get over about 1200 all is well. Its a manual, i just bought the car August 2023 and haven't driven stick in years. It did not have this issue until about 2 months after I got it. No CEL on, cam deviations are below 1deg, rough running values are below 1 with an occasional spike to 1.5 and no misfires detected. All measurements at idle.
Since my ownership I have done the following maintenance:
Date KM
Aug-23 165000 Purchased car
Aug-23 165250 CEL on for code P0491 and P0492 (insufficient SAI flow)
Aug-23 165550 Cleaned air box
Aug-23 166000 New air filter
Sep-23 166125 Repaired driver door lock cylinder
Sept 8 2023 166500 Manometer tested crankcase at 5.25 @ 800 rpm
Sept 20 2023 167000 Brake pads all around
Sept 30 2023 167250 Installed PCCM
Oct 7 2023 167500 Oil change, installed magnetic drain plug, spin on adapter, scoped bores through plug holes - clean at the tops, changed spark plugs
Oct 19 2023 168650 Noticed an unusual hesitation, low RPM under load, intermittent
Oct 30 2023 168721 Purchased winter rims and tires
Nov 6 2023 168880 Cleaned throttle body
Nov 20 2023 168950 Installed Winter rims and tires
Dec 15 2023 169735 Installed oem motor mounts, connected +ve lead for SAI pump, cleaned and lubriacted SAI check valve, found loose bolt for oil filler tube, tightened, changed gas cap o ring, CEL off
Here is what I have tried from a list on another thread
1) Italian tune up: Take it out and blast it at 6+k for a while.
This really helped temporarily. After a good run it ran much better with less hesitation and less frequently but was back to more frequent when driving next a few days later
2) Try running in Sport (if equipped) to see if it hesitates in that mode.
No difference
3) Computer/throttle map reset via battery disconnect for 30 minutes.
No difference
4) Try Techron fuel additive.
After watching the Jake Raby video about additives I think I'll give seafoam a try before my next oil change
5) Run ethanol-free gas a few times with Heet gas treatment.
Will try this next time I can make to the closest station an hour away
6) Open gas cap, start engine, idle for a while, stop, re-close cap.
No difference, I did change my gas cap o ring recently
7) Same as above except for oil fill cap.
The idle goes way off and runs rough
8) Look for vacuum leaks in hoses.
When I was in there to diagnose the SAI CEL all the vacuum lines looked good and since my manometer test was in spec I think I'm good here but I have the parts ready to make a smoke machine and will get to this eventually.
9) The Oil vent hose could have a vacuum leak.
No checked
10) Transmission fluid could be low.
It manual and the fluid is scheduled to be changed in the spring
11) Fuel filter needs changing.
I believe this is in the tank, I haven't looked into it yet
12) Fuel pump is malfunctioning.
I was considering putting a fuel pressure gauge in to check, has anyone done this? What pressure would I expect?
13 Automatic Transmission Filter needs changing.
N/A
14) Automatic Transmission Fluid needs changing.
N/A
15) Catalytic converter clogged.
How can I check this?
16) Throttle plate sticking.
I cleaned the throttle body and watched it operation when I put the battery back on and it appeared to move freely to me. Is there another way to test?
17) Vacuum leak.
See above
18) Oil vent hose causing a vacuum leak.
Where is the oil vent hose?
19) Wait until it goes away.
Wouldn't that be nice
20) Stop accidentally touching the Tiptronic controls by using proper grip.
N/A
21) It's a software issue, and we'll never have a solution until Porsche admits it is happening.
N/A
Any help, ideas, comments or opinions would be great!
Steve
2007 C4
Since my ownership I have done the following maintenance:
Date KM
Aug-23 165000 Purchased car
Aug-23 165250 CEL on for code P0491 and P0492 (insufficient SAI flow)
Aug-23 165550 Cleaned air box
Aug-23 166000 New air filter
Sep-23 166125 Repaired driver door lock cylinder
Sept 8 2023 166500 Manometer tested crankcase at 5.25 @ 800 rpm
Sept 20 2023 167000 Brake pads all around
Sept 30 2023 167250 Installed PCCM
Oct 7 2023 167500 Oil change, installed magnetic drain plug, spin on adapter, scoped bores through plug holes - clean at the tops, changed spark plugs
Oct 19 2023 168650 Noticed an unusual hesitation, low RPM under load, intermittent
Oct 30 2023 168721 Purchased winter rims and tires
Nov 6 2023 168880 Cleaned throttle body
Nov 20 2023 168950 Installed Winter rims and tires
Dec 15 2023 169735 Installed oem motor mounts, connected +ve lead for SAI pump, cleaned and lubriacted SAI check valve, found loose bolt for oil filler tube, tightened, changed gas cap o ring, CEL off
Here is what I have tried from a list on another thread
1) Italian tune up: Take it out and blast it at 6+k for a while.
This really helped temporarily. After a good run it ran much better with less hesitation and less frequently but was back to more frequent when driving next a few days later
2) Try running in Sport (if equipped) to see if it hesitates in that mode.
No difference
3) Computer/throttle map reset via battery disconnect for 30 minutes.
No difference
4) Try Techron fuel additive.
After watching the Jake Raby video about additives I think I'll give seafoam a try before my next oil change
5) Run ethanol-free gas a few times with Heet gas treatment.
Will try this next time I can make to the closest station an hour away
6) Open gas cap, start engine, idle for a while, stop, re-close cap.
No difference, I did change my gas cap o ring recently
7) Same as above except for oil fill cap.
The idle goes way off and runs rough
8) Look for vacuum leaks in hoses.
When I was in there to diagnose the SAI CEL all the vacuum lines looked good and since my manometer test was in spec I think I'm good here but I have the parts ready to make a smoke machine and will get to this eventually.
9) The Oil vent hose could have a vacuum leak.
No checked
10) Transmission fluid could be low.
It manual and the fluid is scheduled to be changed in the spring
11) Fuel filter needs changing.
I believe this is in the tank, I haven't looked into it yet
12) Fuel pump is malfunctioning.
I was considering putting a fuel pressure gauge in to check, has anyone done this? What pressure would I expect?
13 Automatic Transmission Filter needs changing.
N/A
14) Automatic Transmission Fluid needs changing.
N/A
15) Catalytic converter clogged.
How can I check this?
16) Throttle plate sticking.
I cleaned the throttle body and watched it operation when I put the battery back on and it appeared to move freely to me. Is there another way to test?
17) Vacuum leak.
See above
18) Oil vent hose causing a vacuum leak.
Where is the oil vent hose?
19) Wait until it goes away.
Wouldn't that be nice
20) Stop accidentally touching the Tiptronic controls by using proper grip.
N/A
21) It's a software issue, and we'll never have a solution until Porsche admits it is happening.
N/A
Any help, ideas, comments or opinions would be great!
Steve
2007 C4
And, if you've running ethanol blended fuel, DO NOT switch to non-ethanol, you can force a phase separation of any water that's currently mixed with the ethanol enhanced fuel that will just cause another issue. Just out in the seafoam as it will eliminate any water.
Last edited by Petza914; 12-18-2023 at 04:03 PM.
12-18-2023, 05:11 PM
#199
Track Day
Thanks, I'll have a look at the switch and test it out. I did read that the clutch switches can cause similar issues. I didn't think this was my cause as the stutter isn't really an on/off type of feeling, more of a misfire. You can definitely hear it in the exhaust and feel the shudder until it builds some rpm. Could the faulty brake switch cause this type of hesitation as well? Interestingly enough I have had a check rear right brake light fault come up on the info center a few times. When I had a friend check while applying the brake all the lights were working. I'll report back on the test results of the switch and replace it if anything seems amiss.
Also thanks for the tip on the fuel. Its hard to find non ethanol fuels here in Canada so that's fine with me to leave that one alone.
Also thanks for the tip on the fuel. Its hard to find non ethanol fuels here in Canada so that's fine with me to leave that one alone.
12-18-2023, 05:56 PM
#200
RL Community Team
Rennlist Member
Rennlist Member
Thanks, I'll have a look at the switch and test it out. I did read that the clutch switches can cause similar issues. I didn't think this was my cause as the stutter isn't really an on/off type of feeling, more of a misfire. You can definitely hear it in the exhaust and feel the shudder until it builds some rpm. Could the faulty brake switch cause this type of hesitation as well? Interestingly enough I have had a check rear right brake light fault come up on the info center a few times. When I had a friend check while applying the brake all the lights were working. I'll report back on the test results of the switch and replace it if anything seems amiss.
Also thanks for the tip on the fuel. Its hard to find non ethanol fuels here in Canada so that's fine with me to leave that one alone.
Also thanks for the tip on the fuel. Its hard to find non ethanol fuels here in Canada so that's fine with me to leave that one alone.
Does it have the hesitation every time or is it kind of random, and if random, is it usually happening right after you leave a stop as that's when I noticed mine was more prevalent. I've had to replace it in both my 997s for the exact same behavior but at different times, and in both cases it cured it.
Last edited by Petza914; 12-18-2023 at 06:01 PM.
12-18-2023, 06:10 PM
#201
Track Day
Just replace the switch. When it starts failing, it's an intermittent thing that feels like the pedal is doing nothing then all is normal. Because it's intermittent, it's also hard to test as it might seem like it works every time when testing.
Does it have the hesitation every time or is it kind of random, and if random, is it usually happening right after you leave a stop as that's when I noticed mine was more prevalent. I've had to replace it in both my 997s for the exact same behavior but at different times, and in both cases it cured it.
Does it have the hesitation every time or is it kind of random, and if random, is it usually happening right after you leave a stop as that's when I noticed mine was more prevalent. I've had to replace it in both my 997s for the exact same behavior but at different times, and in both cases it cured it.
It doesn't "feel" like a dead pedal but more of a misfire. The engine is trying to rev but you can hear the exhaust bup bup bup bup then back to normal above 1500 rpms or so.
For the peace of mind I'll just replace the switch like you suggest to eliminate that as a possibility.
12-27-2023, 01:57 PM
#203
Sorry you are having issues, especially as a recent buyer. Hope it does not sour you on the brand. When sorted out, these cars are wonderful.
I was reading through your timeliness. Hesitations began shortly after spark plugs replaced. Not sure how old your ignition coils are, but several years ago Porsche updated part due to excessive cracking. The newer coils are much thicker 31mm and require a longer bolt 40mm. You may want to check that and update.
Another thing I did not see mentioned, or maybe I missed it. Clean or replace Mass air flow sensor.
Unfortunately these cars are very sensitive to fuels and water in fuel lines. One bad batch can cause hiccups and bucking broncos for the entire tank. The chevron tech fuel cleaner has been my go to for those situations, but I have never used ethanol gas here in Southern CA. So unfamiliar with pros/cons.
Hope you can find a solution, but those few suggestions were always my first check points.
I was reading through your timeliness. Hesitations began shortly after spark plugs replaced. Not sure how old your ignition coils are, but several years ago Porsche updated part due to excessive cracking. The newer coils are much thicker 31mm and require a longer bolt 40mm. You may want to check that and update.
Another thing I did not see mentioned, or maybe I missed it. Clean or replace Mass air flow sensor.
Unfortunately these cars are very sensitive to fuels and water in fuel lines. One bad batch can cause hiccups and bucking broncos for the entire tank. The chevron tech fuel cleaner has been my go to for those situations, but I have never used ethanol gas here in Southern CA. So unfamiliar with pros/cons.
Hope you can find a solution, but those few suggestions were always my first check points.
Last edited by qikqbn; 12-27-2023 at 02:00 PM.
12-28-2023, 11:01 AM
#204
Track Day
Sorry you are having issues, especially as a recent buyer. Hope it does not sour you on the brand. When sorted out, these cars are wonderful.
I was reading through your timeliness. Hesitations began shortly after spark plugs replaced. Not sure how old your ignition coils are, but several years ago Porsche updated part due to excessive cracking. The newer coils are much thicker 31mm and require a longer bolt 40mm. You may want to check that and update.
Another thing I did not see mentioned, or maybe I missed it. Clean or replace Mass air flow sensor.
Unfortunately these cars are very sensitive to fuels and water in fuel lines. One bad batch can cause hiccups and bucking broncos for the entire tank. The chevron tech fuel cleaner has been my go to for those situations, but I have never used ethanol gas here in Southern CA. So unfamiliar with pros/cons.
Hope you can find a solution, but those few suggestions were always my first check points.
I was reading through your timeliness. Hesitations began shortly after spark plugs replaced. Not sure how old your ignition coils are, but several years ago Porsche updated part due to excessive cracking. The newer coils are much thicker 31mm and require a longer bolt 40mm. You may want to check that and update.
Another thing I did not see mentioned, or maybe I missed it. Clean or replace Mass air flow sensor.
Unfortunately these cars are very sensitive to fuels and water in fuel lines. One bad batch can cause hiccups and bucking broncos for the entire tank. The chevron tech fuel cleaner has been my go to for those situations, but I have never used ethanol gas here in Southern CA. So unfamiliar with pros/cons.
Hope you can find a solution, but those few suggestions were always my first check points.
Thanks for the tips I appreciate any help I can get.
I did clean the mass air flow sensor when I did the air filter so I'll be sure to add it to my list. Thanks for pointing that out. That being said should I consider replacing it as a possibility?
I didn't really suspect the coils as they all looked in good condition and there is no CEL or pending codes for misfires, can they still be the culprit without any other indication or symptoms? I considered the possibility that I didn't properly gap the four prong spark plugs I put in but I wasn't really sure it was necessary. I will have to double check the coils next time I'm in there as I'm not sure if they are the updated versions or not. Does anyone know what resistance values they should test at?
I also considered the possibility that the change in oil (from Liqui Moly 5W40 to Driven DT40) may have altered the operation of either the lifters or cam solenoids.
I've been through quite a few tanks of fuel and tried a different brand as well with no measurable difference.
It's quite random when it happens, every drive at least a few times but not all the time. Start off from a stop and it will chug and spit until the RPM builds to about 1500 and all is fine. Next start off its smooth. If I rev it a bit more then what I consider necessary it wont stutter at all so I can drive around the issue but knowing its there leads me to believe there is something wrong. I can sometimes blip the throttle and it revs smoothly and other times it wont under load or not. It didn't do this when I first bought it, always was smooth, I cant seem to find anything in the durametric live values but I'm a bit new with that so there could be things I'm missing. If anyone has any info on what to look for there that would help.
The idle is relatively smooth but it feels like there is the odd miss and the needle does move slightly with that so I ordered the fuel injectors from LN and plan on installing them soon so I'll see if that helps the idle and stutter then go from there.
I'm not sour on the brand at all ... yet. I do like a challenge and knew that these cars came with some issues. I also enjoy maintaining and fixing things so when this gets solved I'll have that satisfaction as well.
Last edited by Shift4; 12-28-2023 at 11:08 AM. Reason: Added some info
12-28-2023, 11:29 AM
#205
RL Community Team
Rennlist Member
Rennlist Member
The multi electrode Bosch plugs are pregapped. Don't mess with trying to gap them as you'll do more harm than good.
12-28-2023, 04:13 PM
#206
Track Day
02-05-2024, 08:40 PM
#207
Track Day
I just replaced the injectors on my car with the ones from LN. I did the ignition coils from the Porsche dealer at the same time. The car runs significantly better. Idle is much smoother and power is more linear through the rev range. On throttle hesitation is completely gone!!!
02-05-2024, 08:54 PM
#208
Awesome, great to hear this! What was the ballpark labor/parts cost to replace all the injectors? Glad you got it sorted out. It's always a great feeling having your car perform as expected 
02-05-2024, 09:26 PM
#209
Track Day
The injectors were about 600 CDN by the time they got to my door and coils were about 1000 CDN with the longer bolts from the dealer. I did the work myself and yes I'm so glad it's running well again!!
