Sluggish TDI
 

My mom has a 98 new beetle with the TDI. The car has 215k miles on it, and is dangerously sluggish. VW has gave the run-around on what it is and just wants more money. It has been slacking in the power department for some time now. It had a map sensor and glowplug codes. New glow plugs and they cleared the code. I've heard about the intake carboning up, but the dealership said it was at 40%, and that it really wasnt that bad. It won't hold speed or power on the cruise control, but stick your foot into it and it resumes what power it has left. Anyone have an idea??

Yes...

There are a few things here.
1. Find a new dealer - these idiots don't know what they are talking about.
2. The EGR has likely coked right up and can't function properly or at all, providing really low boost.
3. The manifold is probably plugged far more than 40%. You don't spend 2 hours taking it off (yes it takes that long) only to say it's 40% and put it back on without cleaning it!
4. The cleaning job is easy if you have some decent tools, a wash bin and about 2 L or spic and span. If this is your first time doing it expect it to take about 8 hours from start to finish. I've done this so many times I could for the most part do it with my eyes cloed. The number 1 culpert is idling. And the number 2 issue is not driving the car like you stole it - trust me when I say that these cars MUST be driven hard, really hard. They are designed to travel at constant speeds over 180km/h so shift at 3000 RPM for starters.

If you have any questions - let me know.

Thanks for the quick reply. The dealership has seemed to be pretty sorry this time around. They fixed the a/c and it lasted a whole 100 miles. EGR sounds like the likely culprit, you can barely hear the turbo anymore, and it used to scream.

That is likely what it is then. Take the IC plumbing off and careful and mindful of the routing as there isn't lots of room and pull off that flutter valve. Clean it up, reinstall and you should be good.

My guess would be a bad MAF sensor or the wastegate actuator is stuck, or sticking. The actuator sits on the bottom of the turbo and its exposed to all of the road grime. You can try and clean the rod, but more then likely it will need replacing. The replacement actuators have protective shield on them. If you have access to a VAG COM you can drive it and monitor it to see whats going on.

P.S. Glowplugs will not cause a loss of power and more then likely your going to need to replace the glowplug harness, cause I'm sure the fault will return.

Sorry, but I've got to disagree with you here. The MAF's seldom ever go bad - dealerships just like changing them! Unless he is missing the OEM skid plate there will be limited gunk on or near the turbo.

I've been wrong before but his symtoms are classic manifold coke and valve stick (I don't know the technical names for that - just how to fix it).:w2: I do however agree that the harness will need replacing as the code on the 1 through 4 will come back and the trouble is the harness doesn't actually know which plug is on which end so it is best to replace the harness and the 4 plugs. This is a simple repair as well.

Your wrong! :poak: I've seen plenty of MAF's go bad. If you hook a scan tool you can monitor the readings and watch them fall flat on there face. Sometimes off of idle, sometimes under heavy acceleration. Most later model V-dubs have MAF problems, that why VW extended the warranty on them.

Not trying to tell you you're wrong but I've seen this many times. Dealership does their scan, fixes the MAF, car still bites and the whole time it was the coke. End of the day if he does have a VAGCOM and can look at it - they are easy to clean, cheap to replace (dealership won't tell you that, though) and are seldom the real cause.

I know that's where you used to work but I've had a few of these cars and fixed them all - both mine and my old clients cars so I'm entitled to my opinion - which I still think I'm right from what he said.:ph::w2:

There is a vacuum line that is up near the firewall in the center that kept popping off on my wife'd TDI Beetle. It's like a little 1/8" line. There is a T-connector that is white. I'd check that. Next thing I would point a finger at would be the intake/EGR. My wife's beetle would periodically would be sluggish after I fixed the vacuum line. Got the intake/EGR cleaned out and it runs better now than when we got it at 89,900 miles on the ODO a year ago.

They could use a borescope without taking of the intake. That is how our dealer looked at ours before they wasted 2 hours.

I had both go on mine this year. My EGR gunked up and needed to be replaced back in January of this year. Then in May of this year my MAF went. The EGR did not cause a power issue but it was either stuck open or closed so I could not start the car. Did not notice a power problem. But the MAF was a big power loss. I would say half power.

Notes from my two differnt failures.