Car wont accelerate after right turn onto city street

I have had this issue happened twice to me now and the most recent incident was this morning. This is a 2001 C4 996 tip. Around 52000 miles. I have owned it since Easter. Tires are P4 and appear to have decent tread and the last time I looked tread was good on inside of tire as well. I believe 18 inch wheels. The first time was pulling out of my development and making a right turn onto a city street in a "Pouring Rain Storm". The second time was a right turn onto a street after waiting at a light. Dry pavement and no cinders or gravel that I heard or felt on the rode. What happens is just after I make the turn the car loses acceleration. It also feels like the tire is gaining losing traction and there is a little more noise coming from the pass side rear. If it was a standard trans I would say the clutch is slipping but it is a tip. It lasts maybe at most a couple of seconds and than goes away. Getting on or off the gas pedal does not seem to do much of anything. 1. Could it be low on transaxle fluid or is the additives, if this car has any, breaking down now that it has 52k on it? 2. Is the differential acting up? 3. Is there any connection to the fact that the first time was during a very heavy rain storm and this second time was the day after driving in a heavy rainstorm with lots of water on the road- Maybe a sensor is getting wet? It is kind of scary as any car behind me is not expecting this to happen.

This is probably your PSM- Porsche Stability Management. Pulling engine power and throttle inputs, activating ABS, to keep the car on-line/straight. What are the DOT Code Dates on your tires? The tread may look OK, but they could be old and hard.

Can you clarify how you were driving? Were you pulling away from the stop normally or were you hammering the gas? I'm just trying to understand if you were losing traction or if you have a mechanical problem.

No Htwo O - will have to check. Ubermensch - I was not hammering the throttle - just barely on the throttle. BTW- during the "Wet" road condition I did not notice any tail wagging the car stayed in a straight line - albeit a "slow" straight line. What was alarming was the first time it happened I pulled out made a right and right behind came a person from the other side of the street making a left right behind me. I was glad the person was paying attention as they were expecting me to accelerate ahead of them not come to a crawl - infact it was so alarming I pulled off in the grass along the side of the road wondering what the heck just happened.

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That's because the PSM is doing its job. Check a few other small things too: 1) Tire pressures 2) Directional tires mounted properly

I've had this happen before too, and in my case I believe it was because of worn tires and it was PSM kicking in...

Is it possible the C4 was converted to a C2? Still think it's normal and the PSM. And crappy tires....wet roads....heavy right foot.

I wish I could blame it on a heavy right foot but that was not the case. I am still pretty easy on this beast. No way to tell that I know of that it is still a C4 other than when I saw it on the lift and it all looked OEM. I have not done any winter driving with it yet and this "Condition" kind of scares me. Just weird that if it is a tire issue why it has only manifested itself twice considering how many other right hander turns I have made with it.

If you can safely jack-up one side of the car, and rotate one of the wheels (say the front)....then the rear wheel will also rotate. This would confirm it's still a C4 and give an indication to the health of the differential.

did the motor stumble/loose revs?

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The viscous clutch implemented C4's were/are so non-functional it would have NO effect. Even the VSC in my '01 F/awd RX300 will pre-emptively dethrottle the engine if I attempt to accelerate into a tight turn from a stop. With my '01 C4 even the very slightest instance of rear wheelspin/slip under power will result in engine dethrottling and TC braking.

"did the motor stumble/loose revs?" I am pretty sure it did and I attempted to compensate by giving it some gas. Both times I failed to see what the tach was doing. The first time I was afraid of getting rear ended the second time I would say it all happens pretty fast to catch the tach. Anyway I looked at the DOT on the tires at lunch time All tires had DOT XT 4L 9859 Two had a stamp of (0411) a third may have been (0611) but the culprit tire - the tire on the right rear was (3608) I am guessing 0611 is either June 2011 or November 2006, but what is 3608? BTW- Retraced my route as of this morning but nothing unusual happened on the right hand turn. Edit: I searched on the web and 0611 is sixth week of 2011 and 3608 is 36th week of 2008. Please correct me if I am wrong.

The reason for my question is twice I encountered a similiar event while leaving a stop sign and turning right. The first time the car stumbled and I gave it more gas and it came back to life but it spooked me. The second time I lost power making a right turn again a valve seat shifted/failed and I lost compression and coasted to a stop. Now I hope you just encountered your PSM due to wheel slippage but if your car's motor actually stumbled and did not intentionally cut power you could have a worn valve seat. Good luck hunting down the issue.

"The second time I lost power making a right turn again a valve seat shifted/failed and I lost compression and coasted to a stop." I sure don't like the sound of that ! How much mechanical repair did that entail? And how many miles were on your engine? -Don

Sorry Don, I hate to write such things but it did happen to me. If you experience a loss off compression push the clutch in and coast to a safe place and park. DO NOT try to start the engine. If a valve seat comes loose you will damage your piston, head and cylinder. I had 70,000 miles when it happened to me. The valve seats are known to fail but it isnt very common. I had to rebuild entire motor due to cylinder damage but if you continue to loose power and your sure its not PSM or fuel/spark related you should consult a good porsche mechanic and let him evaluate. Rebuilding your heads could cost $3000+. Again, i hope it is something more simple in your case.

This happens to my mdx when the vtm fluid (differential) fluid is either low or water has gotten in and spoiled the fluid. Since you have tip in a c4 id start there.

This has happened to me on several nondescript corners over the course of a few months, but I have been able to replicate it on multiple occasions. There is one corner that has drainage across the road looking something like this and a slight incline afterwards: These road features are pretty common in SoCal. If I power out of the corner while the front is heading up the incline and the back wheel falls into the drainage "trough", power is cut immediately by PSM. There is also a corner that is an right hand uphill yield that flattens off around the corner before heading back up the incline to the right that PSM gets confused/interferes with. Imagine this white line on this diagram representing elevation change around a 90 degree right hander: What are the elevation changes on the corners that have caused the issue?

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You are correct.

It is sure weird that a valve seat would happened to you that way. I could see a loose electrical wire or fuel starving. But I can't imagine how a tight turn would shake a valve seat loose. Plus it would have to have come loose twice in your case. On the other hand I can't see how a tire that has got old and lost traction would cut lose on me on dry pavement at low RPM's causing engine to drop rpms. But I sure experienced it. I guess I can't understand how it would be any different if I had brand new winter tires and caught a little ice on the inside rear tire. Would I expect the engine to almost shut down in that situation? My two conditions were mostly flat. The first on the wet road was slightly downhill. No crowns on the roads here in North Carolina Don