So this car I put on no more than 120 miles in the past two weeks since I've owned it is begging to freak me out. A few days ago the battery died, I needed to do emergency start procedure, and it did in fact start I drove it for a few days and it is seemingly holding a charge now since I am starting it every day since. So this issue may or not be related to the resetting of the system when the battery dies or not, this is where I need help.

I was going down a hill 2 days ago and decided to punch it the car quickly went up to near redline in regular mode and I let of the gas because a hill was approaching, when the car coasted up the hill with my foot off the gas I applied a little bit of throttle to get up the rest of the hill and when I did the car started shuttering, like it was misfiring, or flooded almost. Like a deep bassy "put put put" the car moving back and forth , forward and back.

I immediately pulled into a gas station and shut it off. Waited 15 minutes, started it back up , started normal, idles perfect drove it to my garage it drove with zero issues even gave half throttle was very smooth. Started up the next day and sounded perfect idled fine but didn't drive it anywhere. So that brings us to today (the next day), I started the car with intentions of only letting it run for a few minutes. So it started fine, higher rpms at first because it is cold. Then when the rpm's dropped to normal idle after initial warm up (10-15sec), that noise started again out the tail pipe, like a put put and then a small drop in idle rpm's. Like something is not in sync. I thought it was going to cut out. But after 3-5 minutes of doing that misfiring sound the idle resumed as normal and it didn't do it for the remainder of time I had it on.

I'm just worried there may be something very wrong here. The best way I can explain that feeling when driving would be the feeling right before you run out of gas, like your hitting the gas but your car is just putting and not responding as it shimmys back and forth.

Could this be coils? Plugs? Issue from the battery going dead and resetting?

Please help! Thanks, JOSH

 

I would suggest that you now seek professional help. That is a very expensive engine to repair. It is better to get it checked out before you possibly damage something internal. You may have a piece of carbon floating around in the combustion chamber because of the low mileage or slow driving conditions, and when you redlined the engine you may have blown some carbon loose. If that is the case it is a matter of running carbon solvent through the engine. Lots of luck.
Ron

 

I have heard of similar issues from other people related to spark plugs, most notably when the car is tuned and the plugs are getting old. That is the cheapest and easiest first step to at least rule it out, but I would not freak out so much. The issue is intermittent and what you're hearing is misfiring which means something in the ignition system, so if I am understanding the descriptions correctly you most likely aren't dealing with any huge issues such as the turbos, internals, etc. Just be sure with these cars to keep a rather large and easy to access emergency fund :/

 

I am taking it to VW to see what they can come up with. Nearest bentley dealer is 350 miles away so that's just out of the question. I mean my feeling is after it initially did that I shut it off and drove home fantastic and I had the revs up to 4 k or so and it was super smooth up to 80 mph and down to a stop and nothing. Only 2 days later on start up it returns. If it was a big thing it probably wouldn't go away like that. I've read in other forums a lot about vacuum leaks, because come to think of it 1-2 minutes after it first happen I did hear a loud electrical whine that sounded like it was coming from mid to rear of drivers side. I almost thought it was an electrical transformer on the street lights or something, then I realize you don't hear those in the winter only when it's hot out. Nevertheless I will at least come back with codes and such. I m worried the codes are going to be worthless until reset because of the recent battery dying incident. Any thought here. Thanks again posters above :-)

 

Quick update: Today I started it up, the "throaty" put every5-10 sec is still there on idle but it is far less noticeable then yesterday. I drove the car a few miles. Drove excellent engine wise, but I did notice that my 5-6 shift is a little harsh, the 4-5 was always a bit harsh but not the 5-6. Now since this issue 5-6 is harsh as well. It feels to me like computer issue since battery death/reset. Can all these unrelated things be going wrong because in fact my battery is still low, would it cause malfunctions in fuel ratios or transmission issues. Just a little odd how the car ran absolutley perfect until the day after the battery died and I had to do emergency start. FYI the car starts fine now , NO low battery warning (because I'm starting it everyday). No warning lights on what so ever. New battery will be the first order of business. But could the low battery , and reset (battery dead) cause all these weird things to happen even when the car is on? I feel the car needs to be reset back to normal like it was before the battery died, like it's a computer thing.

 

Hello Josh,
Give me a call if you want, YES the batteries could cause this problem, you should have them both load tested out of the vehicle, or at least disconnected, Also if you do not have a VAS scanner for Bentley, a Ross-Tech will work to clear the codes, also there in really no resetting of the vehicle, I remove or disconnect both batteries say for 20-30 minutes and then re-connect, then clear the codes with scanner, and no a parts store scanner will not do the correct job, BUT you could also have a fuel filter, fuel pump (2), coils, plugs, vacuum leak, ETC. problem, was you check engine light flashing in the cluster when she stuttered, at 32,000 miles, when was the last tune-up [plugs] ?


As far as VW checking out the vehicle, that should be possible, but please be sure to ask if the technician has worked on a Phaeton or Bentley, if not, I would go elsewhere...


As I am 230 ish miles away, it's a little far for a meet, coffee, and checkup, BUT Jason Giannetti (516) 398-2016 in Valley Stream is about 180ish miles from you, I have been to his shop, spent many a phone call trading info, he will give of his time to help you understand what you need to know, also, I have spoke with members here whom have had major work preformed by Jason, and he is the MAN to see !!


Johnny J J 908-507-6357 anytime.

 

Thanks so much I will definitely give you a call !! FYI I called vw and they pretty much told me without the Bentley factory scanner they will have no idea what is wrong, they pretty much were like there is no point having us look at it. I'll give you a call , thanks again for helping I'm so lost at this point lol. - josh

ps never a check engine light or any error light yet, and as far as tune up, probably never I'm sure!

 

Hello Josh,
How did things turnout after the battery change ?

 

Well after the battery change I've had the car hooked up to the CTEK charger when not driving. Everything seems to be ok. It's driving normal. Just a few things i am curious about. When I start in the cold on first fire up the rpm's shoot up to a normal cold start level for the first second then rpms drop down almost like its going stall for a second, then kicks back up to normal cold start idle. Is that normal, because most of the time it fires strong on cold start and keeps that higher cold start idle without dropping down at least for the 10-15 secs. It happens every 1 out of every 3 times I start it roughly.

Second thing, my 4 to 5 automatic shift is a little rough like I can feel it, all the other shifts are like butter almost unnoticeable. Same thing with 6 to 5. Anything going into 5 does it. Does this mean something may be going wrong. 33k miles. BUT i used the paddle shifters for the first time yesterday and EVERY gear shifted perfect, EVEN the 4-5 was flawless. So I don't get it??

 

When you cold start the car and the rpm's drop, what happens if you step on the brake? Does the roughness go away? If so, you might have a vacuum leak. Also, what is the ambient temperature when you start the car?

Re: the transmission shifting. When was the fluid last changed? Given the mileage, it is unlikely the fluid was ever changed. Sometimes old fluid can cause the symptoms you describe. Changing the fluid is not a trivial exercise as it requires removing the bottom casing on the transmission in order to do it properly. There are several posts on this subject in this forum.
Also, I believe the transmission can be recalibrated electronically (ie VAS5054A computer).