Raulvelas8

I own a 2011 panamera 4 pdk automatic transmission. I have been having this issue for months and it has happened several times.
No lights come on when it happens or after.
While driving i start feeling like the car is being held back and brake pedal starts becoming shorter and stiffer. The car feels heavy and takes more effort to accelerate. It feels like the car wants to come to a stop. When I come to a stop the brake pedal feels hard like when the hold function is on. At this point the car does not move forward by itself while on Drive. Its like the brakes are engaged holding the car still. In order to get everything back to normal I have to push the brake pedal hard the farthest down and release. I then hear a noise like brakes releasing and the car moves normally. I have videos.

Im trying to figure out what needs to be replaced/fixed. (Brake booster, master cylinder, or anything else)


Thank you in advanced for your help.

GDWinSRQ

This could very well be a transmission issue. Try this procedure first. It costs nothing and it puts your 13 year old car back to factory settings.
It has worked wonders for mine and lots of other older PDK's.

​​​​​​https://rennlist.com/forums/panamera...ocedure-4.html

Good Luck!

Mike Murphy

Are the wheels and brakes hot after a short drive? It could be a brake booster issue whereby the engine vacuum is pulling on the master cylinder causing the brakes to be applied.

Raulvelas8

Yes first time it happened I didn't know what was going on so i drove it like that on the highway. Once I stopped, it smelled like burnt brakes i think mainly from my rear wheels

Mike Murphy

It could also be a malfunction of the stability management system (and/or ABS) whereby it thinks it needs to apply the brakes to control the car due to wheel slippage. Other car models have had this problem before.

You don’t happen to have odd/wrong sized tires on the car, do you?

I would find a shop that wants to charge you $150-$200 to diagnose. $400 sounds ridiculous.

PanameraCharger

Sounds like an electrical glitch. Get the battery tested

Mr Tee

Simple tests first , if a wheel is hot to touch after a drive , you have a sticking caliper . If you have smelled brakes then this is a clue .

huskeric

agreed... on another car, took me forever to diagnose a rubber brake line had internally collapsed, thereby causing a caliper to stick.
You may want to take a closer look at those rear calipers and I would also bleed to brakes to see if there are any fluid restrictions. The pads may also tell a story, as well as the caliper pistons.

But yes, agreed with several of the above - it does sound like dragging brakes.

Chaos

$400 sounds like a dealer…

coulter

Agree with others sounds like a sticking caliper. I dont see how a transmission issue could cause this.

But just understand, an older Porsche Panamera is going to be expensive to service and repair if you take it to the dealership. Either find a good independent shop or find a different car, because it's going to be a few thousand for pretty much anything.
If a $400 dealer fee freaks you out, wait till you see what they want to replace the calipers, pads and rotors.

MR2Aaron

Does it pull to the left or right at all? Do you have to hold the wheel off center to get it to drive straight?

I agree that this sounds like a sticking caliper, but if it tracks straight, that implies that both calipers on one axle are sticking the same amount, which would be somewhat unusual.

What I would do is lift all four wheels off the ground, put the transmission in neutral, and then manually turn each wheel, looking for any that don't turn freely. If you find any that don't, then you troubleshoot that. Maybe then start the engine and check all four wheels again (with the gearbox still in neutral) and see if any are now sticking.

If the wheels don't feel sticky when turned manually, engine running or not, that implies a computer/traction control/abs issue, where it's deciding to apply the brakes for some reason.
If the wheels stick with the engine running, but not with it off, that suggests some sort of vacuum booster/master cylinder problem.
If the wheels stick all the time, that suggests a mechanical issue, like one or more sticking calipers. I'd look at the rears first, particularly for issues related to the parking brake.

Lacking the ability to DIY all this diagnosis, I'd go looking for an indie shop.

djdonte

One hour of labor is pretty standard at any shop, including a dealer, to diagnose. 400 sounds like a little much unless they really are charging 400 an hour. Most dealers in Houston metro area are 250/hr. If you get the work done they typically waive that fee. I agree with another poster tho, if you're balking at the diagnosis price you're really going to like the estimate the dealer gives you. I'm not even sure 400 gets you an oil change from the dealer. Try a good indy shop if you can find one. They will be significantly cheaper than the dealer.

Raulvelas8

Thank you everybody!

-Car has correct size tires for both front and rear.
-I already know and feel when its about to happen by the pedal feel so I pump the brake quickly so I do not force the car. I want to avoid driving it when its stuck.
-Had the car for 9 years already and always used a friend mechanic. Unfortunately this time we have been unable to pinpoint the issue. He also mentioned the ABS system could be the issue.
- The car does not pull to the sides and the steering wheel feels normal. It mainly feels heavy like its being held back. It takes longer to reach gears and once I let go of the gas it will slow down like if i was pushing the brakes softly.
- The issue happens randomly and only after I drive around. I have been unable to replicate the issue.
-I am going to try a local European shop I found. My local Porsche Dealer charges $400 hour rate