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Hey guys, I was doing a search on google for a problem that I am having with my 01 Jetta tdi and came across this site. I have found some great info and I wanted to present my problem/get your thoughts. Here are the details of the car/problem. Please forgive the length but I wanted to be thorough.....

-01 Jetta tdi, just shy of 100k, timing belt/water pump changed by local shop (1 month, 1k miles ago), fuel filter is brand new (changed after the problem started)

The problem is that when driving the car suddenly becomes unresponsive/bogs down when throttle is applied. This happens at out nowhere and without warning. The car will be running perfectly fine and then I lose all acceleration while driving. When it first happens, I can VERY SLOWLY reach about 25mph (I could run the same distance faster than driving). Then within 1/2 mile of driving, I can barely reach 5 mph at full throttle, it almost stalls, and the exhaust spews light/medium grey smoke that smells horrible (almost a burning smell). Turning the car off and restarting immediately had no effect, the problem was still there.

This has happened 4 times within the last 2 weeks or so (travelled by plane a lot recently so I have not driven much). The first two times that it has happened, I could let the car sit overnight and it started just fine as if nothing was wrong. I could drive it around town for a day or so and then it would happen again while driving with no warning. The third time was this past Thursday and it happened within 1/2 mile after driving. It sat until this morning, I drove it around for 10 miles and then it happened again.

Only 1 CEL has been thrown the whole time: code P0402, EGR excessive. This was thrown just once this whole time and it was thrown during a normal operating time. No CEL thrown while the problem is happening.

So.........................I am wondering if it is the fuel shutoff solenoid that is acting up from time to time and practically cutting off all fuel flow????? This might explain why it goes from perfectly normal acceleration while driving to very poor to only being able to reach 5 mph and the car wanting to stall within a 1/2 mile distance. ANY THOUGHTS on the problem would be greatly appreciated.
 

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There are so many things that could cause engine running problems. Yours seems more extreme than normal though. http://www.myturbodiesel.com/1000q/multi/limp-mode-TDI-fix.htm See this article for troubleshooting steps, then report where you're getting stuck. Manual or auto?

Timing belt, fuel filter done on schedule?

The fuel shutoff solenoid is a simple on or off spring loaded solenoid. I can't see why it would activate during normal driving unless it lost voltage, in which case the engine would stall instead of being just crawling. It's possible it's not closing fully and still letting fuel by but I'm guessing it's not the problem.

It's probably not the MAF since the car runs fine otherwise. Since you have an EGR code, start by checking the EGR function and clogging.
 

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Discussion Starter #3
There are so many things that could cause engine running problems. Yours seems more extreme than normal though. http://www.myturbodiesel.com/1000q/multi/limp-mode-TDI-fix.htm See this article for troubleshooting steps, then report where you're getting stuck. Manual or auto?
Auto. As mentioned, the timing belt was done at 99k. The fuel filter is replaced every december, but I also replaced it again when this problem first started a few weeks ago as it was a simple/relatively cheap thing to replace.

Thanks for the article. I have already read it as it was the thing that brought me to this site.

For example:

1) MAF is not the problem (replaced at roughly 75k). I did the normal check for it.

2) Visually checked all vac lines as best as possible (hard to do on the cloth covered ones). I would also expect a CEL if vac was not at the proper level.

3) I checked the EGR, it was pretty clean (I cleaned it very well about 1 yr ago).

The only thing that I have not checked is the N75, but again, I am not throwing codes.

I only threw the "EGR excessive" code once and that was NOT when the car was acting up. After I cleared the code, checked the vac lines, and checked the carbon build-up in the EGR, the code never came back again.

I am thinking that it is a problem associated with the fuel system, but I am not sure what to check......
 

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Check the fuel system back to the fuel tank. Lift the rear seat and there's a round cover. Underneath is the fuel tank access. Use a wrench to open it. Have a bucket to catch the fuel. Lift out the level sensor and fuel pickup. Sometimes they get clogged there. If you can't narrow it down, buy a VCDS and do some datalogging while driving because it can show problems right away.
 

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Check the fuel system back to the fuel tank. Lift the rear seat and there's a round cover. Underneath is the fuel tank access. Use a wrench to open it. Have a bucket to catch the fuel. Lift out the level sensor and fuel pickup. Sometimes they get clogged there. If you can't narrow it down, buy a VCDS and do some datalogging while driving because it can show problems right away.
Thanks for the suggestion. I am on the road most of this week, so I will hopefully get to check that out this weekend.

Some general questions with this:

1) What does it look like clogged? What is clogging it (deposits from fuel? rust? etc?) Is it typically something that is easy to spot once you look at it?

2) If this is the problem, can the fuel pickup get "stuck" without warning and while driving?

3) I assume that as the car sits overnight that it can become "unstuck/unclogged" and this is why the car typically starts up like nothing was wrong the day before?

4) Is there a certain method that should be used to clean them?


I do appreciate all of the responses so far. THANKS!
 

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whoops, skipped over that part. If it's clogged you'll see black goo on the screen on the pickup. Diesel fuel can grow algae or other stuff. It's possible this is the cause - a big hunk covers the fuel pickup and becomes unclogged while sitting. If this is the case, after cleaning the screen, dump some diesel fuel biocide in there to kill whatever's left and change the fuel filter as instructed or after 2 tanks.

After thinking about your problem, it's probably not a problem with the turbo unless the turbo is somehow completely seizing up. In limp mode, you can still do 50-60 mph if you try hard and acceleration sucks but it's better than you describe.

There are arrows on the fuel filter hoses. Make sure the return line goes to the plastic T. I think it wouldn't cause your problem but worth checking anyways.

It's most likely not relay 109 because that normally causes total engine stalling but IIRC someone had a problem that was the relay which resulted in bad running.

Is it possible the EGR valve is stuck wide open? If you apply vacuum to the valve's vacuum hose, does it open and then close normally?

Is the anti shudder valve plastic arm broken? Maybe it's flapping shut by itself. This is the throttle like flap that's on the EGR valve. It's spring loaded and can be manually moved. Test it by opening and closing it by hand by pressing on the lever arm. Here are some possible causes of the error code P0402: EGR valve stuck open or faulty, EGR system faulty, vacuum, wiring, or solenoid valve faulty.

You can swap the N75 valve, the one that controls turbo boost with the EGR on your model engine, to test the solenoid valves and isolate the problem.

Lastly, your TB was changed 1 month ago but since the car runs fine most of the time, it doesn't sound like it was messed up. If the job was botched it's possible for the belt to skip a tooth and run horribly. Skipping a tooth at the camshaft would mess up the cam-crank timing and skipping a tooth at the injection pump would mess up the injection pump timing. Too far off on the pump and it stalls. Too far off on the camshaft and you get valve-piston contact and engine damage. Look through the timing belt writeup ALH engine for pics of what it should look like.
 

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Discussion Starter #8
Thanks for the help! I am out of town for the next few days. I hope to have a chance to look at it this weekend (including the fuel tank area). I will certainly update at that time.

I will also pick up some diesel fuel biocide and dump that in if need be. This car spent the first third of its life as a farm car (that is surprising given that it is in great condition). Thus, it was running off of farm diesel from 01-04. Perhaps that fuel does not contain the same additives as that required for non-farm use? Just a thought.
 

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UPDATE: I pulled the fuel sending unit from the fuel tank. The filter was spotless and there was a very very small amount of brown dirt (?) inside of the unit at the bottom. The fuel that was in the unit was light green and no particles floating in it. I cleaned the fuel sending unit and put it back in.

Is it possible that this fuel sending unit could be malfunctioning from time to time?

The car started up just fine, except that sometimes the idle would jump between 800-1k rpm a couple of times and then reset at around 900. The was a small amount of grey smoke coming out of the exhaust. It had a burnt smell to it (almost like fireworks after being set off).

I guess I am going to have to spring for a vag-com unit. I really didn't want to dump any more money into the car but I guess this is something that needs purchased to try and figure out what is wrong.
 

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As mentioned above, my TB was changed 2 months, 1200 miles ago. 1000 of those miles was from a round trip from Boston to MD and back 1 week after the TB change. So I have only put about 200 miles on the car in about 2 months. Those two months have also been the start of my INTERMITTEN power-loss problems.

I pulled the TB cover tonight. UNFORTUNATELY, I saw a nice row of white paint marks on the crankshaft pulley (?) directly across from the coolant reservoir. The TB was done by the local Sunoco.

So are my problems attributed to my timing being off? Would the timing being off lead to intermitten power loss thats comes out of nowhere and is gone after the car sits for a day or so?!?!? Or could the mechanic have used the markings as an initial setting and then adjusted the timing from there.

I do not know how nor do I have the tools to see if the timing is off. But could it explain all of my symptoms?
 

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Somebody did a mark and pray belt job. You can't do that on TDI. You have to use the tools or else the camshaft and injection pump timing will be off. Can you see the injection pump pulley? I'll bet that if you checked the camshaft slot it's off and the injection pump timing is off. Also make sure the tensioner is tightened clockwise, the pointer is on, and the tab is in the hole or else it'll be ready to blow. There's a video of how it moves in the timing belt FAQ for ALH engines. I'll bet they didn't replace the motor mount bolts either. If they break or strip the aluminum mount the engine will fall down.
 

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Discussion Starter #14
Thanks for the response. After reading about numerous TB nightmares, I was afraid of the M&P TB change, so that is why I looked tonight. I will see what I can make out tomorrow and I am also making a trip to the mechanic to talk about the car (it is only 1 mile away). I am going to have to find someone with a vag-com to do some tests.

If this injection pump timing was off, wouldn't I have a continuous problem as opposed to the car running fine from the start and then developing problems down the road?
 

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Anything is possible. You'd think that would be the case though. Maybe even the last mechanic did the mark and pray and this one did it the right way. Have you checked relay 109? Maybe the ECU is bad and failing when it warms up. That's what happens with relay 109. If you can only find relay 601, you're looking at it upside down :p
 

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I have the more reliable grey 109 relay but I might just replace it since it is so cheap to do so.

I am also going to replace the thermostatic tee (on top of the fuel filter) as this has not been replaced since the car was purchased almost 10 yrs ago. I am seeing more air bubbles than expected in the fuel line so perhaps this is the problem.

Can anyone guide me on how to test the integrity of the fuel system using my mity-vac pump? I am not exactly sure how to do this.
 

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A few tiny bubbles is normal. Bubbles 1 cm long are not. Also, I'm pretty sure that a bad fuel sending unit won't cause power problems since the fuel pump is mechanical and that wouldn't be a very good design. I think there's a check valve in the fuel sending unit though.

However, going back to the timing belt, check all the timing belt index spots since it's suspect. You don't need to buy the tools, just set the engine to TDC using the flywheel mark, remove the vacuum pump and use a straight edge to check the camshaft mark, and use a pin to check the injection pump and 3x 13 mm bolt positions. Refer to the timing belt article for pictures.
 

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A few tiny bubbles is normal. Bubbles 1 cm long are not. Also, I'm pretty sure that a bad fuel sending unit won't cause power problems since the fuel pump is mechanical and that wouldn't be a very good design. I think there's a check valve in the fuel sending unit though.

However, going back to the timing belt, check all the timing belt index spots since it's suspect. You don't need to buy the tools, just set the engine to TDC using the flywheel mark, remove the vacuum pump and use a straight edge to check the camshaft mark, and use a pin to check the injection pump and 3x 13 mm bolt positions. Refer to the timing belt article for pictures.
The bubbles are about 0.5 cm in come in large clusters (almost too fast to count) of 10+, especially if I lightly wiggle the fuel filter and/or the fuel line going from the filter to the IP a little bit.

I have an apt with the head mechanic at the Sunoco where the work was performed tomorrow morning. I told him that I wanted to him to hook up the VCDS and that I wanted to see the injection pump timing charts for myself.

What else should I ask to see???? Should I ask him to do as you describe above, setting the engine to top dead center and proceeding from there?
 

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The mechanic may be insulted but the facts are the facts and your car is running poorly. Marking the timing belt is not an acceptable way to do the timing belt because of the way the camshaft and injection pump timing are set. Remember that the mount mount bolts are sensitive because they are torque to yield bolts going into an aluminum mount. If reused the mount or bolts could fail.

Also, you don't know if they were the ones who put the paint marks there (unless they look fresh) or that they didn't use the correct tools. However, paint marks normally means they didn't. If you look at the videos, when you tighten the tensioner, the camshaft sprocket and injection pump sprockets move. The camshaft and injection pump don't move because you are supposed to loosen their sprockets. This ensures that camshaft and pump timing are correct after tensioning the belt.

If the injection pump was timed correctly, the injection pump timing should be within the boundaries of the timing graph as shown at the end of the timing belt writeup. It has nothing to do with camshaft timing though.

I'd hard to say how many bubbles are too many just by describing it but it sounds like you have an air leak since you said you get more bubbles when you wiggle the lines. It's possible the fuel lines going from injector to injector need to be replaced or there's an air leak somewhere. The pump is self purging so air bubbles get worked out by themselves.
 

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Thanks for the response. I saw the TB write-up a few days ago. I will look at it again.

I am the original owner and this is the first TB change. Unless those marks are there from the factory, then the mechanic put them there.

I have my worries about the quality of the TB change. When I picked the car up from the garage (1 mile from my house), I noticed that it would groan when going around turns. I got home, popped the hood, and noticed that the PS fluid reservoir was practically empty!!! I drove straight back, talked to the head mechanic (nice guy, but not the one who performed the work as I had hoped). He apologized profusely, yelled at the mechanic, and then topped it off with that expensive VW grade PS fluid.....That is what makes me question the rest of the TB change.
 
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