Chrono

Yes I promise I used searched. I found a lot on this subject but I need to consolidate and get my thoughts together. Help!

My car has what appears to be a common problem with the 997: Accelerating from a stop, car moves a bit then hesitates big time. Then, power comes back on abruptly and strong.

Car: 2006 Carrera S. 23k miles. Tiptronic. Sport Chrono.
Occurrence: Usually once per "outing" of city traffic. So maybe once per 6 to 12 intersections.
When: Warm engine/oil. Cool or warm day. Raining or not.
How: Very digital - loss of power - then a digital ON. Power loss is about 1 to 2 seconds.

Observation 1: I *think* it is more common when accelerating from a stop and turning.
Observation 2: On two occasions, I have seen the transmission gear indicator LED put itself in Manual mode. When the hesitation recovers, it goes back to Auto mode.

I have not characterized the RPM because I'm so freaked when it happens I'm too busy driving. I need to take it out to the country a troubleshoot further.

Engine, Transmission, Traction Control. Dunno yet.

OK, about the consolidation of data, I'll start that in the next response, and I'd love to hear your stories on how you solved this and how. Tiptronic or not, S or not.

Chrono

This data have to do with What People Have Tried or Suggested, as gathered on this forum and a few others. Possible fixes, possible folklore:
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1) Italian tune up: Take it out and blast it at 6+k for a while.
2) Try running in Sport (if equipped) to see if it hesitates in that mode.
3) Computer/throttle map reset via battery disconnect for 30 minutes.
4) Try Techron fuel additive.
5) Run ethanol-free gas a few times with Heet gas treatment.
6) Open gas cap, start engine, idle for a while, stop, re-close cap.
7) Same as above except for oil fill cap.
8) Look for vacuum leaks in hoses.
9) The Oil vent hose could have a vacuum leak.
10) Transmission fluid could be low.
11) Fuel filter needs changing.
12) Fuel pump is malfunctioning.
13 Automatic Transmission Filter needs changing.
14) Automatic Transmission Fluid needs changing.
15) Catalytic converter clogged.
16) Throttle plate sticking.
17) Vacuum leak.
18) Oil vent hose causing a vacuum leak.
19) Wait until it goes away.
20) Stop accidentally touching the Tiptronic controls by using proper grip.
21) It's a software issue, and we'll never have a solution until Porsche admits it is happening.

Chrono

PhilD

Not sure I have anything to add that you don't already know. Could be any number of things, maybe something as simple as a vacuum leak, or could be something that takes more tracking down like a fuel pump or pressure regulator.

I'd start with the easy stuff, Italian tune up, Techron, etc. Then start looking for stuff like vacuum leaks. I think Durametric shows fuel pressures, so logging that data may be worth doing and seeing if you can see anything that changes when the hesitation happens.

SFZ GT3

Have you checked error codes? Any recent engine, chassis, wiring work, repairs? Don't take this the wrong way, but......are you sure your driving/acceleration technique is smooth and consistent? Even a slight, early lift throttle could take a moment or 2 to recover, especially with the fluid connection of the trans to the wheels. Finally, are you sure it's not trans related? Slip, grab, etc as a result of impending trans issues?

I hope it's simple, good luck and keep us posted.

Psymon

When I first got my 2006 C2S Tip, it hesitates at about 1200RPM. It usually happens (or more noticeable?) when I press the gas panel harder, and I don't notice this if I press down very gently / slowly. it can happen either when the car is idle or accelerating from stop, no issue when cruising as its above 1200RPM.

What I tried so far:
2) Try running in Sport (if equipped) to see if it hesitates in that mode.
3) Computer/throttle map reset via battery disconnect for 30 minutes.
4) Techron fuel additive. (edit: um, yeah)
and cleaned MAF, throttle body...

Replaced:
A) Fuel filter
B) Fuel pump
C) AT filter
and spark plugs

.... none of the above really fixed the problem. And the next thing I was going to wait to do is replace the 4 x O2 sensors.

But now after a few months it seems like the problem has either gone away or I got used to it! So I'm going to leave it for now.

997_Toronto

I have noticed this too on my manual 997.1 base Carrera. Am thinking I hesitate a bit on take off so I don't 'take off' but will have to test on an open road.

Chrono

Thanks for the replies !!

PhilD,
Durametric is a great idea. After I complete my initial troubleshooting I'll do that. Durametric sounds fun to do anyway (i'm an engineer).

SFZ GT3,
No work to the car except my own routine maintenance. Regarding my driving technique, while I'm not adverse to taking that as a possibility, I don't think so. With an automatic trans, what could I possibly be doing wrong? And speaking of the Trans... I have noticed on two occasions that the transmission puts itself in manual mode during the hesitation, then goes back to auto mode when it recovers. Odd, eh? However, the RPMs don't go up so it's not a slip. But this may be indicative of trans issue.

Psymon,
What I have is exactly what you describe. Very light accel = no issues. Hard accel = no issues. It's somewhere in-between.
I'm sorry you've spent the money for those changes to no avail. At least it didn't hurt and you've got "new stuff" now. Fuel filter is in the gas tank isn't it? And the AT filter is big coin to replace, no? Thanks for your input, greatly appreciated. BTW, mine has "behaved" on my last two outings.

997_Toronto,
I'm a big Rush fan. Don't you get tired of people telling you that just because you're in Toronto?
Anyhoo, yeah, I want to get out in the country and give this a big old fashioned verification test. I'll report back.

And thanks to everyone for not cussing me out for starting this thread even thought there are more like it!

Psymon

The fuel pump and filters were replaced during the last regular service done by my trusted indie, so I'm not sure where and how hard these they are to replace.

Chrono

I've had some issue-free days after:

• Full tank on non-ethanol 93. ($4.13/gal )
• Battery disconnect to reset mapping

Placebo effect likely in full swing but we'll see. I did have one episode of hesitation but not the all out drop for 2 seconds.

For sure, the C2S likes the real gas.

Captsteve123

I had this issue and it went away when I replaced the oil vent hose that is crosses through the engine to just behind AC compressor.
I had an O ring leaking, which is not available anywhere, unless you buy the hose. I want to say it was a vacuum leak, as once the new hose was replaced, never had the problem again.

Chrono

Thanks Captain. Added your case to a new section called Specific Known Fixes that have worked for one or more people in message #2 above.

Perk10

You don't always use 93?

Chrono

Thanks Perk, yeah always 93 but not 100% ethanol free which requires a special trip and mo' money. I'm lucky to find 100% gas with 93 octane.

To find pure gas in your area, try: http://pure-gas.org/ -- no affiliation

Captsteve123

Chrono,

Well the car hesitated in 2nd gear for the first time since changing the hose that had an O ring leaking. I just pushed the clutch in and out and gave it gas and it cleared it immediately. This is such a hassle to deal with as the dealerships and even specialist do not have any idea what maybe causing the issue.
Full tank of gas, 93 octane, weather damp, temp 66 degrees.