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Happy Saturday, everyone! My girlfriend’s Jetta TDI has had an on-going issue that only appears very sporadically. While on the highway, the glow plug light begins to flash, the engine loses power, and begins to decelerate. It does not stall, but when stepping on the accelerator, all it does is shudder and continue to decelerate. Once we pull over to the shoulder, we turn it off, wait a couple seconds, and turn it back on. It starts up perfectly normal, and will drive just fine for another few weeks. I recently acquired a code reader (actron cp9125), and we hooked it up this morning, only to find that it had no stored codes at all. When i read the manual, and some other posts on TDI forums, it looks like it could be a number of issues that cause this to happen, but I need some help finding a good starting point to begin troubleshooting it. Any advice is greatly appreciated. Thanks!
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with a diesel engine there is one major difference between a gas engine, it requires compression too ignite the air fuel mixture rather than a spark, fuel is injected into the hot compressed air and burns expanding pressing down the piston.
low fuel pressure will cause drivability issues as fuel pressure is ultra crucial for diesels
fuel injectors not atomizing fuel correctly can cause major issues because if the diesel isn’t atomized correctly it will not burn.
compression for a diesel engine is ultra important because it uses compression too ignite the fuel as it is injected low compression wont inject fuel but this would cause un burnt fuel too come out the tail pipe and cause a miss i am sure in one of the cylinders especially when cold.
engine reaching operational temp is very crucial for diesel because the air in the combustion chambers need too get hot enough too make the diesel burn, low engine temps can cause drivability concerns.
its also possible that the engine is opening the waste gate of the turbo, i am almost sure your engine is turbocharged, when that wastegate opens you loose boost, you loose power, your car decelerates in some diesel trucks this is a form of governing!
i will have a deeper look at this… i would also advise checking this and i will look at some stuff some more.
http://www.ericthecarguy.com/faq/solving-automotive-performance-issues
after doing further research i have found that….
the blinking glow plug light for your car is another way for a blinking MIL, telling you there is something wrong with the way something is running, the loss of power i think is the PCM opening the waste gate of the turbo too reduce power, a form of safeguard too the engine.
did some research one guy had a issue with water in his intercooler or even issues with the EGR, could also be a missfire but i would like some codes too narrow things down…
so you have no codes at all? not even history codes? i am kind of nervous too say this is your issue when there is a multitude of issues that can cause your concerns.
What year is the car? This is going to be key as there is 4 or so generations of TDI engines now. All very good engines but they all have their own little things to look out for or happen, and their all different in their own ways.
A flashing glow light does mean something really wrong has been detected and its safe guarding the engine similar to what new transport trucks do. Ideally if it does that again plug your scanner in right away.
Both the flashy light and loss of power are both common with a sensor in the fuel pump on the engine itself going bad in 2005-2010ish cars. It never used to be a replaceable part on its own and requires a whole new part. God dang Pompe Duez engines!
Get back with the year of the car, easier to pin point.
hey JS if this engine runs lean is it pushing enough boost that engine damage can result if it runs lean? if this is the case low fuel pressure will be VERY bad and you can burn pistons and warp valves!
Thanks everyone for all the great info so far. The car is a 2010, and has about 35000 miles on it. The engine is a 2.0 turbo diesel. When I try to pull up the codes, my reader says that there are none, and there aren’t any saved on the computer either. It sounds crazy to me that it wouldn’t even save them, especially with the severity that comes along with some of the issues that the glow plug light could be indicating. It’s making me crazy how the issues are so diverse, and how it’s been difficult to find a place to start the troubleshooting process. It’s one of those problems that just hides away until the most inconvenient time, such as last week when she was going home on 95, and had to pull over on the left side, which made merging a terrible experience for her.
As far as trying to pull the code as soon as it has the issue, will my reader be able to read it without me shutting off the car? I thought that you had to turn the car off and then plug the reader in. If I were to do that, then the problem would just disappear again.
Based on what experience I have with things like this, which isn’t too extensive, it sounds like a sensor is “freaking out” for an instant, perhaps due to some event. Once the car is resets, it sees everything as normal once again, and performs just as it always did, until another instant occurs. I saw that some mentioned problems such as water in the intercooler, or fuel pressure or fuel filter issues, so would those be good places to try and start to look? I’m not sure that these would be the issue, because I wouldn’t think that these would disappear by turning the car off and on again, but if its a place to start, then I’m happy to check it out.
I tried to reply last night and earlier this morning with my phone but it was experiencing some Samsung difficulties.
First things first, 35000 miles is really low for anything major to happen. Is your gal the original owner? If so take it to the nearest big VW dealer. If not take it to a shop in your area that’s got a good reputation working with VW/German cars, in particular the diesel ones. I would try the dealer first and then go to the second option only because it could be a warranty issue.
The engine in that car is a good one! But there is a lot going on. It was their first go at a very electronic controlled diesel engine for improved power and emissions rating. Basicaly they built that motor with the intention of it passing California Emissions. Because of its electronic controlled injection you have sensors similar to a gasoline engine at work, a very high pressure common fuel rail, a low pressure pump in the tank, and a very very high pressure pump up front. They also have glow plugs with a cylinder pressure sensor in them to meter a bad ignition, so you can see how complex they are compared to the old 1.6 Diesels that came in Rabbits and Golfs.
The next thing to bring up is your scanner. Make sure its “Vag-Comm” compatible. Some scanners say they do all cars but believe be without Vag-Comm software it wont understand a VW computer. The good news is that if you have a VagComm scanner you will always find people on craigslist offering to pay someone to scan their car for them.
Without being there to probe and check its tough to stab at it on the internet unless you can find something of a following for the same year and engine with that same issue. I work on plenty old VW diesel engines but I have to admit outside of some oil changes and diesel purge haven’t delt with anything major on one of the new ones from the last 5-6 years. I would get it into a shop ASAP as problems never get better on their own and you really don’t wanna kill that powerplant.
She isn’t the original owner, but we were looking into its warranty paperwork this morning, and it’s still within its 5 year mark. The power train should still be covered. She is planning to call the dealer tomorrow. I’m not sure if my code reader is VagComm compatible, but I’m assuming its probably not. It was only 40 bucks at advance auto, so I’m sure its not too complex… lol! This is my first attempt at troubleshooting a diesel, and it’s definitely been a learning experience. I knew they have a lot of complicated systems in them, but the more I read, the deeper it gets. In a weird sort of way, I’m enjoying it as well. I have always found engine tech very interesting. But I digress.
It’s very good to know that the engine in hers is a strong one. I’m pretty sure whatever the issue that its having will be covered by the warranty, so I’m not tearing it all apart just yet. I’m never one to jump in over my head with these sorts of things.
No questions about it, its a good engine. Just needs some love by the sounds of it.
Newer diesels still work on the same principals as old ones but instead of being big, heavy, clattery, smelly things they have come a long way. The old VW ones literally had 5 wires on them. Oil pressure sensor, Coolant temp for the gauge, coolant temp for the thermo time switch for Glow Plugs, Fuel cut of solenoid, and the glow plug strap itself. If the timing was set properly and all in good health they go forever. But times changed thanks to consumers wanting fuel efficient cars that actually go quick, and meet emissions standards.
The engine in your girlfriends car was a breakthrough in technology that’s for sure. VW didn’t invent it but they did a good job of utilizing it. To reduce noise and increase power the injectors fire up to 3 times in a ignition stroke, and still manage to be more fuel efficient than the previous TDI engine that was cam timed injection like big diesel engines. Much quieter and they make almost no soot. You only have to plug them in if its really cold too. A friend of mine works up north of Edmonton in the winter and had no issues with his not starting.
I like that engine, and the version in the 2011-current. The new ones have sick power. So much torque. And finally engineers started building gear boxes that utilize the low RPM torque so they accelerate very quick. The other added low hassle bonus is that currently the Euro 8 and california emissions laws say that Diesel engines 2.0L or less do not require to have a DEF compatible exhaust system. All the new Audis and VWs with the larger TDIs have a small tank in the back that periodically you have to top up with DEF fluid. And to save you from just driving without filling it up they give you plenty of on dash warnings as well as the car goes into limp mode if it runs out and you try to drive on it.
Hopefully you get it sorted out. I wish I had more experience with the newer diesels. Don’t be surprised if the dealer tries to offer to buy it back from you and sell you something newer. They cant keep their hands on diesels. New or used.
It’s definitely an awesome little car. I love the way it drives on the highway, especially. As you stated, so much low end torque! You barely have to get on it to speed up and merge, and overtaking is a breeze. I used to have a Ford e350 with the 7.3 international motor in it, and while it was the less powerful version of that motor that they put in the vans, you could pretty much throw whatever you wanted in the back, and the engine didn’t know it was pulling anything. That had 215hp, and 425 ft lb of torque. That’s when I really started to enjoy diesels. Man, I miss that truck!
My own car is a Dodge Caliber, and while I love it, even after 164000 miles, I can’t help but wish a little that it was the euro version, because it had basically the same engine as the jetta, or at least close to it, if my memory is correct. I would have went for that engine if they were sold in the USA. I commute a lot, and it would have made the highway a lot more tolerable, especially with fuel efficiency. We calculated her fuel economy when going on a long trip, and I think it had 46 by the computer, and about 43 by my by-hand calculations. Not too shabby for an automatic. Another friend of mine has the 2011 diesel with the manual transmission, and his computer is telling him close to 60! But as I said, I love my Caliber, and have no regrets with it. And now I’m starting to ramble… lol!
Anyhow, she didn’t get a chance to call the Volkswagen dealer today. She’s going to give it another try tomorrow. I’m anxious to see what this problem is, and I will most definitely share all that we find out about it. And let me tell you, she loves that car, and there is absolutely no way she will let them buy it back from her! (I sure would miss driving it!)
Just out of curiosity do you think that gas could have been put in instead of diesel? As many have pointed out it seems like some pretty low miles for issues like that.
Hi there! I can almost certainly say that its not a case of putting gas in instead of diesel. Reason I can say this is our schedule is that we always see each other on the weekends, because we live far apart. She always fills the car up in my region, because its a bit cheaper up this way. She doesn’t drive too far to work, so usually she only drives the tank down about a third during the course of the week, including her trip up here. I’m very envious of this, because i drive about 80 miles a day for work! Should have gotten a diesel myself!
She did manage to call the local VW dealer yesterday. From her description, the person she spoke with was a bit less than courteous to her, and wanted to charge a $125 diagnostic fee to check and see what the problem was. I avoid dealers and shops as much as I can, so is this a common practice? If it is indeed a warranty repair, should she have to be paying anything? It just sounds a little funny to me. When I read the info about the power train warranty, it seemed to cover items internal to the engine, as well as the manifolds. Would this include the lines and sensors for the turbo system? Or perhaps for other systems that are in play for controlling the engine? I’m not sure what their diagnostic test would include, but for $125, I would hope that it’s a little more in depth than plugging in a reader and seeing if the computer has any stored codes.
The last we spoke of it, she was going to check around for local garages that are equipped to deal with VW’s, and see if she couldn’t get it checked out for a lesser price. I hope she keeps the momentum going on this, because it scares me with her driving this thing back and forth when it just randomly drops out.
While I’m thinking of it, she also has a relatively short trip to work each day. I’ve heard in the past that diesel engines like more to run on the highway for awhile, as opposed to a little low speed trip to work each day. Is there any truth to this? Perhaps the engine has gotten dirtier this way? As everyone has said so far, the engine is very young to be having such a crazy issue. Thanks again everyone for all the wonderful advice, and please keep it coming! I’ll be sure to keep you all posted on what we find out.
$125 diagnostic fee is pretty hefty for a warranty claim, especially when they don’t know what they’re actually looking for. They could plug a scanner in and find the problem right away or they might need to probe around a little and do other tests as well. $125 up front sounds kinda greedy to me.
It also depends on your warranty though. Powertrain warranties only really cover catastrophic failures in the engine and transmission for the most part. It doesn’t cover stuff like clogged fuel filters or bad glow plugs, bad turbos, etc.
That said, I would bring it to the dealership and convey your belief that it’s an internal engine problem. They check it for free this way. Just keep pulling the warranty card if they try to charge you something.
Also when they come back with a list of stuff they found wrong with the vehicle, be sure to take that list to the independent euro shop that JS mentioned to have them double check the dealer’s findings. Dealer techs hate warranty work in general and it’s not that uncommon for them to “find” other issues to try to make money off the warranty job.
Your car is covered by the Federal MANDATED emissions warranty. Plus the car is well within the dealership warranty for the power train.
Dig your heels in. I absolutely despise shops that demand a fee when they already know the issue will be a warranty claim. (Had the same thing happen to a Dodge Sprinter I used to drive for the company I work for. It blew the EGR on the Diesel engine. 650 for the part plus labor and diag. fees. They where going to charge the company I work for in full for the repair. Just because it fried at 42,000 miles.. I had to remind them about the Federal warranty. They ate the entire cost, including the diagnostic fees)
Recommendation to at least see what might be going on. If anyone in your area has a “VagCom” scanner, or VCDS (made by Ross Tech. It’s about as close to the factory full computer software there is). The car’s computer is an excellent one, and has the ability to show codes from different modules…and it monitors just about everything. Might be helpful to have someone with that tool do a ‘scan’ but DO NOT ERASE THE CODES!!. These will be needed by the dealership to probe into the issue. Erasing codes also clears the “Freeze Frame” data that the computer recorded when the error(s) took place.
In any event….VW does not like dealing with any warranty work….Do not let them steam roll you into flipping $$ for their work unless it’s 100% NOT covered. Anything emission or within a drive train warranty will be covered, including figuring out what happened and why.
Keep us posted !!!!
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[quote=”quickNpainless” post=105608]$125 diagnostic fee is pretty hefty for a warranty claim, especially when they don’t know what they’re actually looking for. They could plug a scanner in and find the problem right away or they might need to probe around a little and do other tests as well. $125 up front sounds kinda greedy to me.
It also depends on your warranty though. Powertrain warranties only really cover catastrophic failures in the engine and transmission for the most part. It doesn’t cover stuff like clogged fuel filters or bad glow plugs, bad turbos, etc.
That said, I would bring it to the dealership and convey your belief that it’s an internal engine problem. They check it for free this way. Just keep pulling the warranty card if they try to charge you something.
Also when they come back with a list of stuff they found wrong with the vehicle, be sure to take that list to the independent euro shop that JS mentioned to have them double check the dealer’s findings. Dealer techs hate warranty work in general and it’s not that uncommon for them to “find” other issues to try to make money off the warranty job.[/quote]
What he said LOL!! Pretty much followed the same process as I did. All wise words!
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