# car surges off idle when brake released



## bobvomac (Oct 24, 2015)

Just bought a 2010 2.0T wagon. Once the engine is warm, if you release the brake pedal at idle, the car will lurch forward a couple of feet then reconsider it's bad move and the rpm's go back down and this car with a mind of it's own will settle down. But this pattern is repeated over and over if you let it. This means at stoplights, if you purposely give it a bit of gas, it will result in a couple of surges forward, in a jerky fashion until you are well off of idle. With the brake pedal down, there is no surging.

Was wondering if the PCV might be it or the MAF sensor but you would think there would be a CEL for that which there is not. I'm going to hook up my ODB II reader tomorrow to check it out just to be sure. I'll also call the dealer with the VIN to see about recalls.


----------



## kbad (May 26, 2007)

hey man .. congrats on the purchase and welcome to the vortex - more ride detail would help .. i'd check the brake booster vacuum hose ... TSI or FSI - the original stock one is crappy plastic which tends to develop hairline cracks over time and cause the issue you are describing, particularly when its warmed up - if it is the culprit, you can tape it up and see if that helps temporarily .. enjoy the ride .. good luck!


----------



## bobvomac (Oct 24, 2015)

Worth looking at, thanks.
Turns out this happens in reverse also. As to the engine temp, I'll make a note once I test tomorrow. But it goes like this:

- arrive home, slowly pull into the garage since it's a tight fit, put the brakes on before entering to line the car up 
- release brakes
- engine rpm goes up enough to cause a sudden lurch forward, hit the brakes to avoid smashing into things
- release brakes again
- repeat behavior

I've learning to know very closely as to when the lurch will begin and can feather the lurch sometimes but this is not a fix obviously. Also, if I do this outside the garage, it will lurch then the rpm lowers by itself and the car will move slowly forward at a normal speed for an automatic. In other words, only 1 surge per release of the brakes.

The vacuum thing sounds promising, I cannot believe the CPU is the cause of this.


----------



## iqoair (May 30, 2015)

You have a vacuum leak - could be as simple as a dipstick not in all the way. Check the brake booster vacuum connection.... You will probably hear the vacuum leak (Hissing / sucking sound)....


----------



## bobvomac (Oct 24, 2015)

Guys, thanks for the very promising lead.

that ole sucking sound, yahhhh...happens every payday

Is this the part? https://www.ecstuning.com/ES303879/

First off, it does not happen when cold. So I'll enlist the wife to release the brakes and listen for the hiss, thanks. Here's hoping this fixes the 3-lurch dance at the stop lights and stop signs too.

Having come from the 2.8L V6, this 2.0T is sure a change. I don't use it unless really necessary though. I had a T-bird SC years ago and did not deny the right foot at all and ended up after about 4 years with a tired engine, oops...

So this weekend I'll replace the coolant temp sensor on the B5 (for the 2nd time in about 70k) so the wife can start it in the morning and listen for B6 hisses...


----------



## kbad (May 26, 2007)

bobvomac said:


> ... Is this the part? https://www.ecstuning.com/ES303879/ ... it does not happen when cold ...


umm, thats replacement for a mk3, i dont think its the correct one - thought you had a 2010 2.0T, more description would help, eh .. yours would be mk5 but TSI or FSI .. when warmed up the plastic expands and allows for the 'leaks' to open up - if its small enuf, wrap it up with electrical tape to get by .. make sure to check all other similar vacuum hoses in the system ... good luck!


----------



## bobvomac (Oct 24, 2015)

Did not get the results this weekend for detecting the vacuum leak. I'll start googling but due to the DOHC engine, I cannot hope to hear any hissing or leaking due to a vacuum leak unless it was as loud as a vacuum cleaner!

It does turn out the engine is TSI and I'm happy about that. What looked strange was on the right (driver side) of the plastic honeycombed piece that is probably the intake, there's a small tube that is part of the plastic that is pointing to the right that really looks like it should have a hose on it but there is no lonely tube laying below it that would be it's mate. Can anyone verify this tube is supposed to be open?

I did determine that the idle level of the engine is probably a bit low because at a stop light on an uphill street, if you let off the brake the car rolls back a bit THEN that pesky surge happens to raise the idle which will then allow the car to remain stationary on the hill (brake still off) or maybe roll ahead just slightly uphill. So the surge looks to be an attempt by the ECU to rectify a slightly low idle.

Open tube pointing to right (driver's side), green arrow:










Closer up










Lower down, there's another open tube pointing up (white arrow) & another larger diameter plastic "clip" like structure (yellow arrow) that looks like it would like to have a larger hose attached to it.


----------



## kbad (May 26, 2007)

bobvomac said:


> ... Can anyone verify this tube is supposed to be open? ... Open tube pointing to right (driver's side), green arrow ... Lower down, there's another open tube pointing up (white arrow) & another larger diameter plastic "clip" ike structure (yellow arrow) that looks like it would like to have a larger hose attached to it.


hey .. the "green" arrow tube is a dud - look/feel inside, its blocked off .. the others, not sure, i'd have to go look, cant tell from pics .. good luck!


----------



## Raygtimk6 (Nov 3, 2015)

Hi did fixing the brake booster rectify the problem ??
Thanks


----------



## bobvomac (Oct 24, 2015)

*It got complicated*

after buying this used car with 55k from a private party, a mere 1,000 miles later the car started blowing white thick clouds out the exhaust. Towed the car to the dealer hoping it was not the turbo or head gasket and that whatever they fixed would also address the lurching problem.

Turned out 1 injector went bad dumping raw fuel into the cylinder causing the smoke AND to my surprise they covered it under an extended warranty VW did because they knew these injectors were crap. So that was about $1,000 saved

BUT...

The TSI engines deposit uncommonly huge amounts of carbon on the intake valves and VW says they need to be cleaned about every 60k! The mechanic has a TSI himself and had his cleaned (at much lower cost of course). Since the head was already off for the injector replacement, they charged me 2 hours labor to clean the valves and $55 for the cleaner stuff that has to soak on the valves because cleaning them manually.

BUT...

this didn't fix the lurching. They said it's probably the transmission control module that has all the solenoids in it, about $2,000!!!! I hope they are wrong and that it will be something cheaper.

TBC....


----------



## bobvomac (Oct 24, 2015)

*getting scarier with each set of posts on this issue*

searched on "dsg mechatronic" and BOOM! a 16 page thread on it. There is no way what I'm noticing is unusual, even the NHTSA is in on this. VW has a problem and like good Germans, they refuse to admit a problem.

I'll know tomorrow what the deal is because I'm getting the pre-inspection prior to buying the extended warranty. There is no way I'm going to put anymore money into fixing this car before getting an extended warranty. So around 10:30 tomorrow, they word will come back from the service dept if there's any condition that needs to be repaired before I'll be "allowed" to buy a warranty. And that inspection is on my dime, about $100.

The forum started filling up with MU (mechatronic unit) in 2011 so let's see if they have this figured out. I think maybe not because the service coordinator did not mention it when he 1st brought up the issue of the lurch on acceleration.

Unfortunately since no nation in Europe has the consumer protection agencies that the US does, and because the customer is just a bag of money to the European business world, they feel no need to admit anything or go out of their way to fix a known problem UNLESS the NHTSA requires them to do something when they see too many failures on a system. The only reason VW would respond to them is because this is the biggest market in the world for cars and they don't mind losing $100 million if it means making billions in sales.

The ongoing debacle at VW concerning the emissions software cheat they purposely built into their TDI's shows how little a business cares about anything other than the bottom line.


----------



## bobvomac (Oct 24, 2015)

Well, almost 2 months since the OP. I got the extended warranty as this car seems like it's going to pop the lid on expensive stuff too often.

So took it in to the dealer because the surge/lurch is getting worse. They called after inspecting the car and said there were 2 codes in it (why they didn't show up at the pre-warranty purchase inspection I don't understand).

First code was for the turbo waste gate valve, he said that might be causing the problem, at least in part. This is covered by the warranty.
Second was for the oil separator (don't know why there'd be a sensor in that to throw a code). That one is covered by the PZEV warranty which is probably 70 or 100k miles. He said that fell into the category of a possible vacuum leak. I'll have to go looking for pictures and info on what this is and where is it under the hood.

After they road test, we'll see if the mechtronic comes into view as a culprit. I don't think it will since it had the DSG service less than 20k miles ago.


----------



## bobvomac (Oct 24, 2015)

Test drive was initially showing improvement in the surging from idle but after warming the engine up, most of the old behavior is still there. After explaining this to the service dept, they said bring it in and the lead mechanic will ride with me as I demonstrate the issue.

So, from a stop with foot on the brake, take the foot off the brake (giving no gas) and the car delays about one second then surges forward. Happens in Drive and Reverse.

If you do give it gas from a stop, it surges forward in a succession of 3 sharp jerks before smoothing out into a proper, smooth acceleration.


----------



## beringela001 (Dec 5, 2014)

Does it happen if you pump the brake? Press the brake a couple times really hard while stopped and see if the rpms go up. (Could be in neutral if u have an auto)

I had a similar problem and it was the coolant flange.
If you look at your brake booster you have a vaccumm line that goes down towards this coolant flange and comes back up to the manifold/vaccumm Pump t connection.
It's just a pass through at that coolant flange and the nipple gets brittle because of the hot and cold plastic.
What I did was run a vaccumm line directly from the brake booster to the t section, bypassing the flange. Never had a problem ever since.


----------



## bobvomac (Oct 24, 2015)

Good tip. I'll try that.
The lead mechanic agrees it's a transmission issue rather than an engine issue (like vacuum leaks). I also found a phenomenon had worsened. On a hill from a stop, let off the brake and it starts sliding downhill while in drive. It used to b go a few inches but more it goes a few feet. Only then would the transmission begin to engage. Of course this was extremely hard on the transmission clutch plate I would imagine even though it is a manual transmission with a computer grafted on.

So I left the car there and they're going to call Volkswagen because there were no codes that showed up on the mechatronic system last time the car was in. They think Volkswagen may tell them to reset the mechatronic unit to base level and then drive it 50 to 60 miles so the learning procedure takes place. That makes sense because that way nobody has to spend any money except the dealer has to drive the car around for two hours.
That's okay with me since I do have the extended warranty now. If it works, we're all happy.

So it seems the service coordinator was right from the beginning when he said that the mechatronic system might have a problem. What I don't understand is why this wasn't discovered when the previous owner had the DSG service done on it only 18k miles ago.

I'm supposed to get a call today when they have given it the 1st look over.


----------



## arismkv (Jun 17, 2008)

To your last post. My mechatronic unit failed couple thousand miles after the second dsg service. I doubt they really look at anything aside from changing the filter and fluid. 

Btw, I am having this issue you mention, normally when i first start the car in the morning put on drive and let go of the brake. It surges and almost shuts off.


----------



## bobvomac (Oct 24, 2015)

Well, damn...

Neither VW nor the extended warranty cover the clutches. That's a consumable item they both say. So after 55K the clutches wear out and they want me to pay $2,200 for it.

The service coordinator even called the warranty place twice hoping to get a yes on the 2nd try. He said it's not very likely the mechatronic since they typically throw lots of codes when they start having problems.

This is not a good ending to this story.

Can't afford it so we'll have to drive it gently I guess.

anyone have a low mileage set of clultch packs for a 2010 DSG?


----------



## bobvomac (Oct 24, 2015)

arismkv said:


> To your last post. My mechatronic unit failed couple thousand miles after the second dsg service. I doubt they really look at anything aside from changing the filter and fluid.
> 
> Btw, I am having this issue you mention, normally when i first start the car in the morning put on drive and let go of the brake. It surges and almost shuts off.


I hope your deal is a vacuum leak and not a transmission issue.


----------



## bobvomac (Oct 24, 2015)

*Problem solved but at a cost*

VW America had to weigh in on this one and they hit it right as the dealer was not sure what the issue was. At a cost of $2,220 the clutch packs had to be replaced at 57k miles. The surging is gone. The surging had to be fixed because in tight spots, it could have resulted in a disaster if unseen pedestrians were injured.

Hope someone gets something out of this story, it's taken several trips to the dealer and many other phone calls.

I asked the dealer why this pack would go back so soon. He said they can go out at any mileage, that they even had a new car require this same replacement. The repair has a 12k warranty.


----------



## kbad (May 26, 2007)

Merry Christmas, eh .. about time they got you sorted out .. cant believe that with all the tech available to them, and they are THE manufacturer, they can never really actually pinpoint an issue without first blackboxing the hell out of it .. have a safe and happy New Year .. good luck!


----------



## bobvomac (Oct 24, 2015)

thanks for sticking with the thread and for the vacuum leak lead, I know I'll need that info in the future. I have not yet examined to clutches but they will get looked at. How the hell can a clutch that YOU cannot affect with your foot (no clutch pedal) burn out at 56k miles??

As I told the customer rep in service, cars are now so completely overcomplicated that you must accept things going wrong in them. The manufacturers are stuck adding new gizmos every year to make you believe you are getting something better than the leftover previous year car on the lot.

We're spoiled and the price is now coming due, we are paying the piper.

On motorcycles, this point has also been reached with electronics you just don't need unless you race. But worse, the street (non-race) models now have 200+ HP and that is simply too much for all 20 something year olds. The street bikes are now only 10% lower in HP than the race bikes, ridiculous. Lives are being snuffed out every day because of this.

So with that in mind, here I am at Laguna Seca in T5 2 years ago on my race bike:










DAMN!! My pit crew would put sugar in my gas tank if I didn't give equal time for all their work....


----------

