new Passat sometimes stumbles at partial throttle

Quite distressing. I get an ocasional stumble from the engine at partial throttle. Rarely happens, but when it does, it has usually just upshifted (2004 2 liter, automatic USA)
Any Ideas? A simple adaptation, I hope.

Mine has this exact same symptom. I took it in to the dealer and did a test drive with a manager (when of course I could not duplicate the issue.) But they checked with the VW folks and said this is a known issue due to our crappy fuel in the US. They said they will have an ECU software update shortly (w/in 30 days) that should fix the problem. My car was not held at the port like many others reported here on the board. I think that is why my car is experiencing this- I think the ECU was reprogrammed on those cars held at the port.

Mine would stumble 2-3 times at cold startup, so I when I filled up, I added some cetane boost and the stumble has stopped. Dave

Ours stumbled on cold starts as well, until we got through the first tank of fuel, and put BP's B20 in it. I think it has once since then, but it was hardly noticable (only a split second). I was thinking of getting some Cetane boost to put in as well if that didn't get rid of it.

Cheers,

VWYankee

My 2.0L TDI Passat is only two weeks old. I have experienced the "stumble" or "transmission rocking" a couple of times as well. Bad diesel???..only purchased from Citgo (truck stop) and when the dealer filled it up. Hopefully, this is a minor problem and might be the result of the cetane rating as previously described. Any recommendations greatly appreciated by this "newbie" to the VW diesels.

If you can find either a BP with B20 Biodiesel (20% biodiesel), or an Amoco with premier diesel. The latter may be harder to locate, as in my area I only know of one, and there's nothing that would appear different on the pump, but you notice a difference in how the engine operates (much better). I believe there is a list that has been created on some site (maybe be this site?) for stations carrying this diesel. It's been a few years since I've seen that list. Adding Cetane additive to each tank will help as well, as stated above.

Ahhhhhh! /images/graemlins/mad.gif

This sucks. My passat is scheduled to arrive at the end of the month. I am in CAnada. Does that mean that mine will possibly have a reflash even before it arrives to my dealership. I can just add cetane to the fuel I wouldn't want the timing to be set back or anything?


/images/graemlins/frown.gif /images/graemlins/frown.gif /images/graemlins/frown.gif I am going through living hell with my 6.0 Ford diesel and flashes. There are like 20 different flashes and different things each flash is trying address and it only gets worse and worse. I thought this wasn't gonna happen to me anymore, ahhhhhhhh (praying to the VW gods, please deliver us from flashes)

The concensus here seems that it is a fuel issue. If it's true that VW has a fix, and it involves retarding the injection timing, I'm not likely to want to have that done.
Although I've never really believed in them, I'll try the fuel additive.

Any other thoughts on why my Passat stumbles under light throttle, or are we certain fuel is the reason. How widespread is this trouble?

My 04 TDI Passat is about 2 weeks old, I don't know if this is the same problem, but the engine/transmission seems to "lurch" or "hunt" during a slight deceleration from steady state driving usually between 60-75 mph. You guy’s think this is fuel related?
Any feedback is greatly appreciated – Other than this problem; this vehicle very closely matches my 1991 BMW 535i that I owned in quality. I am very impressed.

Isn't the lurching at low speed more associated with the DSG type transmissions. The PAssat is a conventional 5 spd automatic.

I test drove a TDI Passat last week, had the transmission stumble on me and frankly, it made me walk away from the purchase until VW fixes the problem. I was just beginning a deceleration from 45mph when the transmission thing started and it actually shook the chassis slightly. I was otherwise very impressed with the car.

DHU

My 04 Passat started the "stumble" after about 500miles.
Seems to be worse when the engine is cold.
I'm running ULSD which is rated 50+ cetane and the problem is still present. I'm thinking at low throttle the EGR is opening putting more exhaust gases into the intake tract, which could be leaning out the fuel mix?
Does this make sense?

Man, you guys are starting to scare me. I test drove a TDI Passat a couple of days ago and really liked it. I was planning on going by again tomorrow and give it another drive, then put a deposit down a Silverstone sedan they have scheduled to arrive in a couple of weeks. I think maybe I'll wait until things get sorted out a bit and they come up with a fix or maybe I'll take another look at the Jetta GL TDI 5spd wagons they have on the lot. I know they have been there for a while and could easily get one for invoice.

There seems to be 2 different issues here or is it just one? A cold condition engine stumble and a higher speed transmission shudder or are they the same problem? Hopefully it can be fixed with a software update.

Yes, I wonder if it could be a lean condition caused by agressive aplication of EGR. It is indeed as others have described, a stumble under light acceleration. Sometimes an upshift seems to trigger it, but I really don't see it as a transmision issue.
I've just run about 100 miles or so with the additive and BP fuel. I can still get it to stumble, ussually on highway, about 60-70 mph

My Search results for prime diesel ( where I come from we call it ROPA ) /images/graemlins/wink.gif

http://www20.brinkster.com/beowulf9/tdi/PremDiesel/PremDiesel.asp?View=FULL

My diller www.auburnvw.com called me and may TDI WAGON is going to be ready on Monday - info for Washington owners. /images/graemlins/wink.gif

Well, today I drove on an isolated highway, south of houston, it was flat, nice weather, so I accelerated up to about 110 mph for a minute, made a controlled deceleration to 80 mph, and then took my foot of the gas, and the car shook three times, (same "hunting or lurching" that I explained in previous post), as it seems the engine cut out during each shake. It was much more noticable at this speed In conclusion, I would be inclined to think it was engine related. I am not real concerned right now. I hope this info helps.

Seems like many of us new 2.0 TDI Passat owners are experiencing the same problem. If its an "engine problem" should a solution be forthcoming soon from VW?

Thinking about the 1.8T passat we test drove..

a) it too was banging around when it was downshifting. I dismissed it in my mind as agressive transmission behaviour due to no one regular driver to adapt to.

b) on a diesel if you take your foot off the throttle and the torque converter remains locked up the engine is not getting any fuel right so it would feel more jerky when it shifts and has to apply throttle again.

c) did you say 110 mph? How long did it take to get there? My car comes end of the month and I haven't gotton one single solitary phone call for my Toyota 4-Runner.

My Variant stumbled once quite severely on the way home from the dealer. On 2nd tank it stumbled a little at about 1500 rpm in third (one nice thing about this tranny is that you can bump the lever over to Tip and the display shows what gear the car has chosen). I found that I could sometimes initiate this slight stumble by going about 1500 to 1800 rpm in third. On next tank I added a couple ounces of PS cetane booster and a quart of soyoil (I will eventually run B20 to B40 as I did for a year with the Jetta that now belongs to my son). No stumbling so far, not even when I try to induce it. Keeping my fingers crossed.

This was posted on the future owners thread.
Three weeks ago my dealer (Burnsville MN) told me my 04 TDI Passat Varient was at the port and scheduled to be shipped by truck. Two weeks ago he called to tell me it would be here by the 9th of May. The car did not show up so I visited the dealer yesterday. The sales manager told me VWOA just called him back (After he called looking for the car) and infromed him the car is on hold at the Houston port and they would not tell him why!!!
He has four wagons and seven sedans sold and none are being shipped. They do have a demo, and when I drove it, it did "stumble" a few times. The sales person with me also noticed it and thought is was just "Cold"
In any case, I don't have my car and VWOA will not commit to an anticipated arrival date.

I've had the same problem since day two. The first time was at a speed of about 120kph /75mph, after having accelerated up to that speed and then slightly backing off the pedal. It almost feels like momentary fuel starvation(Choke, surge, choke....), about five times within a two second timespan.

I've had the car two weeks today, and have felt it a dozen times since the first time. Although not as severe.

I can trigger it if I hold a steady speed of about 70kph / 40mph on a flat road, and then slightly decrease accelerator pressure to change the steady speed to 60 kph / 35mph. It'll stumble one third of time.

I almost sense that it's something that may work itself out, otherwise I'll get the flash update when it's available.

Regardless of this glitch, I still love the car. Low fuel light came on at just over 700 kms / 435 miles (all city). I'm pleased with the fuel economy considering my slightly heavy foot on the go pedal. I can't help myself. /images/graemlins/grin.gif

Arthur,
Relative to your (b) topic, my deceleration (slight lifting of my foot) from 80mph, the transmission I assume is still in 5th gear, I don't think it would be trying to go back to 4th...at those rpm's. What do you think?
Answer to your (c) topic, it does not take very long at all to get at 110mph, this engine/tranny combo is great because anything above 70mph you are already in 5th (final gear), so you can just go. I asked the dealership what the top speed of the car was, and they told me 134-139mph----I was expecting the usual 108mph.
I guess with the username of nascarfan, you should expect posts raving about performance.
I remain very positive and commited to this car, VW will find a fix.

I picked mine up 2 hours ago! and yes it has the stumble too

Congrat's on the new Passat TOMO.
I new you couldn't hold out too long.
What color, options?

Northern Green Anthracite Leather/wood trim
ESP, Schweet!!

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Schweet!!

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don't you mean SCHWING!

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Arthur,
Relative to your (b) topic, my deceleration (slight lifting of my foot) from 80mph, the transmission I assume is still in 5th gear, I don't think it would be trying to go back to 4th...at those rpm's. What do you think?

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I was thinking that the fuel is shut off if the torque converter is locked and you're decelerating. then when you apply some throttle it should just start firing the injectors and get going. But if your speed slowed enough to need to downshift into 4th - combined with the injectors starting to fire - maybe it gets shaky?

I'm a mercedes tech and MB has a pretty common stumble problem. For MB it is a torque converter lockup issue. My new passat tdi does it too and it feels almost the same. I'm really not worried about it. Most things like this usually go away. I only get worried when they become worse. I've noticed mine in tip mode, 3rd gear, at approx 30+ mph with small increment throttle input. I just use tip mode 4th at that speed. I guess it could be an EGR related thing too. I may play the fuel change game just for fun...

My new 04 passat didn't have this problem at all the first week. But it happened today. It has around 800 miles on it. Kind of makes me wonder if it isn't the fuel.

Randy Q
04 PASSAT WAGON TDI

Interesting, the 04 jetta engine does some funny stumbling when sitting at an idle. You can see the engine rocking back and forth on its mounts randomly and feel it in the interior, namely in the seats.

I've tried many things with the fuel and additives, it certainly does reduce the occurence of it, but it still does it irregardless. I think its an EGR thing on that car too.