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Hope this is not bad forum policy, since this thread is being discussed on TDIclub.

I mentioned to my dealer last week that I get a hiccup every now and than. Seems like a half a second loss of power, than fine. Others have stated that it has happened to them in the 2000 RPM range. I have noticed it most after running the car a short distance, stopping, than returning to the car, restarting, driving, and around 2nd or 3rd gear is were I notice it. But it happened once the other day after the car had ran for quite some time and had been at operating tempeture for at least 30 minutes. Other have mentioned it seem to happen to them with cold engins. Has this happened to anyone on this forum? because my service rep told me to let him know if it happed again. They checked the car, but could not replicate the incident. I want to take all the information that I have read and let the service rep know that others are having the problem ( if it is one ) and what their opinions are.:dunno
 

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Welcome! This is a place where you can discuss anything as long as it's not a violation of the forum rules.

Is it a DSG? It sounds more like it's a manual and you're having a mid rpm hiccup. Yes, it has happened to an number of people here as well.
 

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No Sir, it is a six speed manual transmission!
Just wondering what the cause of this might be? So I could better explain to the Service Rep.
 

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My best guess, and this is a total guess, is that it's related to the emissions system tuning.

My 2006 has an occasional stumble at idle and I'm pretty sure that it's related to the EGR system. It's not that bad so I'm not going to bother trying to track it down. This is a pretty common complaint once you've ruled out camshaft timing, flywheel problems, and worn camshafts. Others have fixed it but it's not on forums and I forget the exact solution right now.

My best guess is that engine stumbling related to the 2009 and newer is related to the interplay between the EGR valves at the intake manifold and the exhaust pipe, engine tuning to meet emissions, and maybe something else that I can't remember right now.

Aftermarket chip tuners claim to have fixed any hesitation or stumbling but they're not saying exactly how so if their claims are true, it's software related, not hardware.
 

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6 speed TDI JSW stumble/stall

I have a 2010 JSW TDI with a 6 sp manual and 7,500 miles; I have experienced the stumble behavior since the very first drive home from the dealer last October when I purchased the car new. The first time it occurred, I knew it was totally out of the ordinary, and challenged the dealer to check codes and diagnose. I described the sensation as a missfire or fuel cut-off. They claimed it was normal TDI performance and sent me on my way. The vehicle has continued to stumble frequently since then, and has been in out of the dealership 4 times to no avail (though they've slowly revealed that they acknowledge the issue as a problem and are working on a fix... see below) as the problem continues. Here's a description of the issues I'm experiencing, all of which appear to be related IMHO:

1. The first characteristic is a stumble at approximately 1,800 RPM just as I release the throttle to upshift from 3rd to 4th gear. The engine appears to cut out for a split second and then jump back to life. It seems to only occur on flat, straight stretches of road and at about 30-35 MPH during moderate acceleration. The stumble here is a single event and the car then proceeds as normal from there forward -- usually not stumbling again during that drive. tt appears to do this only after the car has been parked outdoors (vs in my garage) for a few hours (usually does it during my lunch-time drive after the car's been parked outside at work for 2-3 hours). I would say this occurs once every 4 trips or so. The car has done this ever since my very first drive home from the dealership a year ago. It doesn't matter where I fill up with gas as I've changed stations to see if it's a fuel thing to no avail. I would characterize this issue as more annoying than a safety issue. The safety issue comes later...

- The first 2 visits back to the dealership to have the issue checked, they said there were "no codes" and the vehicle was "performing normally and that the sensations were related to the different torque characteristics of a diesel engine." The service dept also told me "there's no way for a diesel to missfire because it's a compression engine..." Thanks, guys. Not helfpul.
- The 3rd visit to the dealer, they said there was a service bulletin for a software flash and O2 sensor replacement; they reflashed the engine and said that that would fix it. The problem persisted.
- After 4th visit, this one in August, I provided links to the tdiclub.com and myturbodiesel.com forums to the service department; the dealer then came back with this reply, finally acknowledging the issue:

In talking with the shop foreman, Volkswagen is aware of the situation. There is an impending software level update, I believe the issue resides with the EGR system and possibly the regeneration of the particulate filter. Unfortunately VW has not given us the fix. What I would recommend is contacting VW Customer Care and initiate a claim through them, trust me though as soon as I know when this update is available you will be the first to know. VW Customer care's number is (800) 822-8987.

- at the dealers' suggestion, I reported the incident to VW Customer Care


2. The second characteristic is a hesitation sensation when cresting a hill and naturally releasing pressure on the accelerator pedal as I crest the hill. As I proceed down the slope the engine feels like it's hesitating -- not stumbling as it does on the straightaways, but instead just needs a pretty good goose on the accelerator pedal to respond. This appears to be most prevelant at speeds below 50 and doesn't seem gear dependent and more so tied to the releasing of the throttle following an ascent. I would say this occurs more frequently than the single stumble - probably once every 2 trips or so. No warning lights present themselves in any of these instances. And the dealer says no codes are found.
- The dealer service department, despite 4 visits to address this issue, had not been able to resolve it as of August, 2010 and the problem persists


3. The third characteristic, which has actually occurred only once in the year I've owned the vehicle is, what's best described as a slipping-clutch sensation during acceleration after shifting from 1st to 2nd gear. Unlike the first 2, this one happens when the engine is loaded and with pressure on the accelerator. Whereas 1 and 2 happen when feathering the accelerator. This one is much more concerning and, in my opinion, dangerous as the vehicle shakes and has limited power. I think I counted what felt like 4 sequential stumbles that felt like the clutch was slipping. My passengers looked at me like I was driving like a beginner. I KNOW it wasn't my driving and it was clear that I wasn't in control of the engine during this incident. It stopped after 4 or so consecutive stumbles and car continued to drive normally for that engine cycle. Again, no warning lights whatsoever.
- The car is now back in the dealership for this issue as I refuse to drive it any longer

4. The 4th characteristic, which thank god only happend once, was a total shutdown of the engine during braking after cresting a hill at the top of which was a traffic light, which had turned red. The similarities to 1 & 2 in this one was that it involved the cresting of a hill, and the release of the accelerator (after significant pressure, traveling at 50+ MPH while climbing the hill approaching the light). The engine was very warm as I'd just driven for an hour at 75+ MPH on a freeway. So, that's different from the cold-start stumbles on the straigtaways that I've seen with point 1. Anyway, I approached the light, braked with moderate force and noticed that after I'd come to a stop that the engine had stalled out. No power at all. Surprised, I went to start the vehicle and it seemed to take 2-3 times longer to crank. It eventually cranked and then spewed an alarming (think raging camp fire after water poured over it) of thick WHITE/GREY smoke from the tail pipe. So much so that my passengers asked if the vehicle was on fire! No warning lights presented themselves during this massive smoke episode and the car then drove normally thereafter.
- Needless to say, this was the straw that broke the camel's back; i took the vehicle back to the dealer and told them it wasn't safe to operate and that I wasnt' interested in driving it any longer. Oddly, that same day that I took it back, I received this email from the tech advisor:

I spoke with one of your area reps. Friday about the software update being available yet on your vehicle. He is in Detroit this
week for meetings and he is going to speak with some of the engineers. They are using the software update currently, but he is unsure if it is fixing the issue. He is going to contact me when he gets back to let me know if it takes care of it. I don't want you to think we've forgotten and I will let you know hopefully be the end of this week. If you have any questions please let me know.


- I reported the incident to VW Customer Care, and filed a case report with the NHTSA as I believe this is indeed tied to the stumble issue and is a major safety issue; these cars need to be recalled and repaired
- I took the car back that day and am now driving a loaner
- In the meantime, I found stories about the NHTSA investigating stalling issues with VW TDIs that discussions on the tdiclub.com forum suggest are tied to fuel pump failures; while the initial conversations around the stumbling issue appear to be related the EGR valve and the software that governs the regen function, I wonder if the stumbling and stalling are tied to the same issue as I've had both failures (though my stall didn't render the vehicle undrivable like the fuel pump failures being investigated by the NHTSA). I also wonder if the stumbles I'm feeling are also tied to the fuel pump... the stumble could easily be a loss of fuel to the engine -- at least it seems logical....

All of this has me gravely concerned. Concerned about my investment in a vehicle that appears to have a serious design flaw. Concerned about my safety in driving the vehicle. And also really disappointed (because I'm a huge VW fan, believer in diesel technology and someone who waited 4 months for the vehicle to be delivered) that VW doesn't seem to be able to identify the issue.

In the meantime, my dealer says they're updating my ECM with a software update that's supposed to address the EGR issue that they believe is contributing to the stumble. They're also testing my fuel to see if it's to spec/contaminated (which I doubt). And they're assessing whether my incidents above are all related, or seperate. I don't want to drive the car again until all of it's addressed. I'm considering filing a Lemon Law claim in Washington State in the meantime and am awaiting those documents before proceeding.

I'm also awaiting a call from a VW tech to explain to me their position, their guesses, and their methodology for drilling down into the causes of my isssues. VW Customer Care promised I'd receive a call from a VW regional tech in 48 hours.

My dealer's doing the right thing now by taking the car back and giving me another (non TDI) Jetta to drive in the meantime. In the meantime, it's now up to VW to approach the very loyal (and fanatical) ambassadors of their TDI technology in the US who are having these issues, hear the complaints and be honest about their assessment and their attempts to fix them. I'm all ears....
 

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IMHO, these sorts of running problems are either due to fuel or air or something that controls fuel or air.

If it's fuel related, it's because the fuel injectors aren't injecting fuel at the right time or there's some other problem which would throw a code. Failed HPFP are throwing codes for fuel pressure amongst other things.

If it's air related, it should throw a code because the MAF sensor sees a value that is out of bounds, assuming the MAF works.

Because codes aren't being thrown, it's proably working within the normal boundaries of it's software tuning. My guess is that the engine hesitation and the stalling was related to a combination of fuel/air settings due to emissions tuning. There's a throttle in the intake and a backpressure throttle in the exhaust. If either one of these is shut or not timed correctly with the EGR, my guess is that the engine will hiccup. Maybe if these closed or opened at the right time, it caused the stall situation. Unless the fuel is really bad or has water, fuel isn't going to stall your engine like that, and all these bad fuel complaints are BS - older TDI didn't have failures deu to bad fuel unless someone put unleaded in it.

Good idea about filing a complaint with the NHTSA. These sorts of issues could cause a safety issue and the sooner pressure is put on VW to fix it fast, the sooner it'll get fixed.
 

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I feel your pain. Thank you for your report. Someone else posted that they were interested in the Lexus 200h after having some problems with their car. It looks like a nice car but the reason I'm not interested in them is because I like VW and not Toytoa. I didn't even like the Supra TT when compared to similar cars. My general opinion is that German car companies tend to use state of the art technology but also beta test on their customers. If something goes wrong it's certainly not the engineer's fault, of course! Blame the customer. That's the line they've had so far and it sounds like your dealer is working with you to the best of their ability and the shop is being open with you. That's a good start.

Whatever your problem is, it's real, probably not your fault, and VW is aware of problems. I've had hard winter starting from their botched glow plug recall from last year and they are just now beginning to address the issues that many people had. It seems so simple that what they did would have caused a problem and the aftermarket fixed the GP problem. From what I hear, aftermarket tunes have also addressed the stumbling and engine related hesitation problems. However, it's not the aftermarket's responsibility to fix a car under warranty. I agree, VW needs to fix this problems or else their biggest fans will become their biggest critics. 2nd on contacting the NHTSA. This is how things get started.
 

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They suggest that the egr is being told to close too soon, or too much, by the software. The update adjusts that timing, so they say. I understand the car is now flashed. I told the dealer to keep it, assign a tech to drive it to and from work for at least a week, and call me then with an assessment of the efficacy of the software update. If it had continued to just be the stumble, I wouldn't be so hard nosed about it. But as soon as it stalled, it's now a safety issue and one I'm not going to subject myself to again.
 

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JSW Stumble Update

so, i spoke to my dealer's lead tech yesterday. the car has been flashed with a software update related to the EGR valve issue. as i suspected, VW appears to be throwing fixes at this issue and isn't giving the dealer specifics about what the update is specifically doing regarding values/timing/etc. they appear to be a bit in the dark and the approach seems like it's still in the beta stage. while the dealer says the car drove "normally" after the flash, with no sign of the stumble, i asked that they keep it, and assign to a tech to drive as if it were their own vehicle for at least a week. after that point, i will make a decision as to whether to take it back. as i said prior, the total stall and loss of power was the deal breaker, and is a major safety issue. until i have a level of assurance this patch worked, i won't be driving the vehicle again.

speaking of the stall, the tech said that he believes the stall was indeed tied to the stumble, which he believes is tied to the EGR valve issue. he said that the combination of inputs at the point of the stall starved the engine of oxygen... diesels die without air. since it died while i was still accelerating, the engine was flooded. so, when i restarted, the extra fuel generated the shocking smoke cloud...

so, some movement toward identification of the issue, and a technical description linking all of my issues together (whether the EGR valve and the software is indeed the issue, though, doesn't appear to be a definitive VW position on the issue...)

I will keep everyone posted:dunno
 

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Not just the EGR valve, my best total guess is that it's related to the EGR valve, maybe the exhaust backpressure valve, and the intake manifold flap (throttle).

Look through this FAQ article: http://www.myturbodiesel.com/1000q/egr-system-clogging-TDI.htm There are pictures of the EGR/intake flap and cutaways showing the insides. Here are 2 relevant pics - the green is the flap and as you can see it looks and moves like a throttle. The plastic gears that move it have been known to strip on a few high miles cars. The EGR valve does not choke the engine of air but it does route the high pressure unfiltered EGR gasses into the engine. It's downstream of the intake flap so my guess is that it doesn't clog the flap operation.

 

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same issues

Hello,

Zimguy, I have been experiencing the exact same problem on my 2009 JSW with 6-spd manual. The slight hesitation feels to me like the fuel is cut off all the sudden. It usually happens in 2nd or 3rd with no slant to the road. At first it made me think the clutch didn't make good contact but that didn't make sense to me as it had just been engaged and seemed fine. I really don't want to have to deal with this issue but I should probably take it in to the dealer. To be honest these new TDIs are becoming to be more trouble than they are worth. I love the car but I am really concerned about long-term reliability now. I feel like going back to my old sooty 1985 Mercedes 300D. I would like VW to do the right thing here and stand up for their product. It's not the fault of the customer, so the company needs to have some integrity here. This is my second 2009 Jetta TDI as the first one had a DSG trans. that had jolting issues. I really thought the manual would be the way to go but now I'm not 100% convinced. Best of luck to you and I hope these issues get resolved in a timely fashion.

-Jeremy
 

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You bet and good luck. My 2010 has done it more times than not just before engine warmup. 2010 golf tdi six speed. I refuse to let VW tech tell me it is normal. They are getting tired of me. We all need to continually address this issue to VW. Would you have bought this car knowing this hesitation issue was so called "normal"
 

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If I had known it was considered "normal" behavior, I would not have bought the car. It's pretty ridiculous that the older TDIs did not have the same sorts of issues as these new ones have. These cars need to be sent through a more rigorous quality control regiment. Problems that come up so early in the ownership of a new car really take away from the excitement of driving a new car.
 

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Quick update on my last service visit. Left the car with the dealer for a week. The dealer told me that VW Tech Line gave them the "goahead" to flash the ECM with an update to address the EGR issue. The dealer said that they'd already updated another vehicle in Oregon, but weren't yet sure that the update worked. A few days after I dropped the car with the dealer, VW Customer Care (who've been very responsive, incidentally) called to say the update had been completed and the "car was functioning normally with no repeat of the stumble". I told VW Customer Care that I didn't want the car back until a tech had driven it for at least a week and gone through multiple engine cycles. Since the stumble happens once every 4 or so cycles, a single drive was not sufficient to declare it "fixed." The dealer called a week from when I dropped the car and said that a tech had driven the vehicle and that they hadn't been able to replicate the stumble since flashing the ECM. At that point, I went back and picked up the car and told the dealer, and VW Customer Care, that I would now assess whether it was indeed fixed. I noted that the dealer had driven 200+ miles, so figured that was a level of assurance that they'd done their homework. They also told me to use only Chevron or Shell diesel and to keep an eye on the car and let them know if any stumbles occurred. So, I went on my way. The next day the car did what I thought was the same flat-street 35 MPH/1800 RPM/3rd-to-4th gear stumble; I gave it the benefit of the doubt as it was subtle, and continued driving. Today, 3 days after picking up the car and about 10 engine cycles later, the car DEFINATELY did the flat-street 35 mph/3rd-to-4th gear stumble. Exactly the same as before. I also have noticed the downward-slope hesitation once in the last 10 cycles. So, it doesn't appear the update worked.... I called VW Customer Care and reported the issue was persisting, and called the dealer to report it. The tech wants to speak with the senior tech and get back to me about next steps. They did ask about the fuel (which I filled up as the tank was empty after I picked up the car); I told them I filled up with a new tank of Chevron diesel after picking up the car, and that I doubt it has anything to do with the fuel... Incidentally, VW Customer Care paid my October car payment for me -- classy, though I doubt they'll want to do much more of that as the car's definitely going back in next week....
 

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I have the same "flat-street 35 MPH/1800 RPM/3rd-to-4th gear stumble" as Zimguy. It happens every day about 30 seconds after leaving work. I really appreciate your detailed updates. I need to bring my car in to VW to see what they come up with.
 

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Now about a week in since my software flash for the egr issue, the car is still stumbling from 3rd to 4th. The stumble does, though, seem more subtle. Almost muted. It is now doing something new...what feels like a flutter with a corresponding rpm flutter. It doesn't appear to do have any pattern. Or none that I've picked up on yet....
 

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New 2010 Jetta Hiccup

I found this site because last night when leaving from work (50 degrees F), my new (1.5k miles) Jetta TDI bucked horribly for about 1/10th mile, then the car was hardly able to make 25 MPH for the next two or so miles. After warming up for about 5 miles, I got up the nerve to get on the highway - sluggish until after driving for another 15-20 minutes. Also, I thought I might be imagining it, but you've confirmed the intermittent split-second hesitation at highway speed, i.e., 70 MPH, roughly 2,200 RPM. I just talked to the local dealer service mgr. He said he hasn't heard of anything like this (as expected), and told me it sounded like bad fuel. Advised to add a can of diesel fuel additive with next fill-up. Anybody else?... C
 
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