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Discussion Starter #1
2002 TDI Beetle with 130,000 miles

Two weeks ago we re-calibrated the EGR setting using the VAG-COM to 33768, based on the this recommendation. We also performed the intake and EGR cleaning based on the FAQ on this site. Last but not least we changed the air, fuel, and oil filters (and oil itself).

Following that work it ran wonderfully, and we put 700 miles on it driving home from Christmas.

Today, my wife was driving and it all of a sudden dropped power, started sputtering and spit out black smoke (lots according to her, and then blue smoke.) She limped home. I cranked it and it idled just fine, no smoke. However, as soon as I pressed the accelerator it started to sputter and wouldn't accelerate at all. I didn't see much smoke, but I 'think' I smelled more fumes than normal. The check engine light is not on.

From what I've read, this sounds like limp mode, but I would have expected the check engine light to come on. I opened the hood and checked the various pipes and gaskets that we removed/adjusted with the intake cleaning and all appear intact. I only saw two things that concerned me (total newbie here.) One was a noticeable amount of oil like stuff stained/leaking from where the EGR and intake meet. When we reassembled we did not change any seal at that joint (none was present.) Also, while tightening the top back bolt, it felt like it was starting to strip (spin easier) and we stopped tightening it. The other two bolts tightened just fine. The intake is black around and down from that joint and it was clean when we mounted it.
The second thing I saw was an oily substance on the inside of the 2" intake hose that leads to the EGR. I disconnected it at the front near the passenger headlight, and when I poked my finger in it was wet with oil. I thought that would be a dry pipe. yes, no?


I would greatly apreciate any advice and/or direction to begin diagnosing this. I don't have a vag-com but I can rent one from autozone if necessary. I don't have a compressor to do a pressure test either. Is there an alternative method to isolate the problem? Thanks all!
 

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The new opinion is that the EGR recalibration decreases mileage and doesn't solve EGR clogging by itself. It can also cause a CEL/MIL to come on. The TDIFAQ hasn't been updated in a long time so some of the information has changed. See here for some newer info on the EGR system: http://www.myturbodiesel.com/1000q/egr.htm

I would just put the EGR calibration back but the real issue sounds like limp mode. Limp mode does not always produce a CEL/MIL/check engine light. The staining of oil you see is probably a bad connection. Where the EGR and intake meet, there is an o-ring. As long as it's still tight, I don't think this is causing the issue. If it is loose, then it could cause the limp issue.

The staining could also be unrelated EGR weeping. The EGR valve gradually wears down and starts to weep oil out of a hole on the bottom. This is from wear. Don't plug the hole but if it's just a little weeping, I would just clean it. If it's pouring oil then it should be changed as it a major oil leak could be a fire hazard.

The TDI crankcase vent system, high piston pressures, and blowby put some oil mist into the intake. Some oil mist is normal, the rest is burned off in the engine. If it were a gasoline car it should be dry.

Autozone doesn't have a Vag-com, they have generic obd2 scanners. These get most codes but doens't have the functionality of a vag-com. It's free and worth a try though.

A pressure boost leak test would be a good test. The only alternative is to double check all the hoses, couplers, and vacuum lines. The advantage of a pressure test is that it can find hidden or hard to see leaks. http://www.myturbodiesel.com/1000q_how_to/multi/boostleaks.htm

Also see this general limp mode article: http://www.myturbodiesel.com/1000q_how_to/multi/limpmodetdi.htm

It's possible that something worked it's way loose and after a few hundred miles, has got to the point where it's causing limp mode.

You can also try removing the hose at the bottom of the intercooler. It's normal to have some oil pooled in there from the mist. But if it really pours out then it's possible that the engine had a runaway. But the description sounds like limp mode. A runaway is when the engine revs hard and fast on it's own due to consuming oil. If that happens, immediately shut down the engine and pull over as soon as is safe.
 

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If you just did work on it two weeks ago, it might be linked to something you touched in that area two weeks ago. Just a thought. And if you don't have a vag com, how did you recalibrate the EGR? If you borrowed one, it'd be easier to find that one again.
 

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Discussion Starter #4
Thanks for the input guys.

The work was done right at Christmas, after which we drove to Gatlenburg TN (400 miles) for new year and then home to Charlotte (another 200 miles). I do suspect that some of the work we did might be the root cause. Perhaps a hose clamp that didn't seal very well. I will be checking for that (the best I can) in the next few minutes here, per Chitty's recommendation.

I just finished checking for codes using the Autozone ODB2 scanner. It found no DTC codes. Which sucks. At least with a code I'd know where to look. :)

I will get the EGR setting reversed, but it will have to wait (assuming thats not the cause of the problem). I had it set at a shop in Birmingham AL, 500 miles from here. I've got to wait a paycheck or two and order the cable from partsplace to do it myself. That and I need it for future anyway!
 

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Ok... I checked the air hose on the air filter (both ends), the air hose going to the EGR, the two tiny p reassure tubes (anti-shudder?) that connect to the EGR top and the black pressure bulb, as well as the two 1" engine coolant hoses that connect to the intercooler. oh, and the small coolant (overflow?) that comes down from the T joint to the intercooler. All of those were fault seated and clamped tight. Note, I don't have the equipment for a pressure test. So visual is the best I can do.

I cranked her again and it sputtered (RMP drop like the engine was going to die, and then recover) several times and then leveled out into a smooth 1k rpm idle.

So, I pressed the gas (in neutral) and it revved up without sputtering. This was odd, since before it had sputtered when given gas. I raised it to 3k rpm and held it there for a minute and it ran just fine, no sputtering. So I thought I might have inadvertantly tightened a hose when checking previously, and I took it for a test drive.

No such luck. It immediately began the sputtering. I made the block and parked again. Put it back in neutral and revved again. It went to 3k RMP without a problem! No sputtering. It seems to happen only under load. ANY load at all.

Again, the behavior is that when pressing the gas the RPM starts to go up then it drops 500-800 RPM or so as if the engine is going to die. When driving it is constantly doing it.. sputtering along.

Exhaust is noticeably strong. I see white smoke, not super thick, but definitely there.


At this point I'm not sure what else I can do myself. I thought I'd let you guys know what I have found and see if you had any ideas. Otherwise its off the the dealership :( and a big bill.

Either way, this forum (which you guys are the heart of) is great! I've learned a ton reading the FAQs and even if I don't solve this one I am still looking forward to doing maintenance on the cars myself.
 

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This sounds like a fuel issue to me. Are there any bubbles in the fuel line? When you add load, the air bubbles get too great and cause sputtering but during neutral revving the bubbles get worked out. Maybe a loose fuel connection or missing o-ring on the fuel filter? Did you reverse the fuel filter supply and return lines?

I doubt the EGR recalibration is the problem if there are no codes. Is the EGR valve sticking? You can check by moving the lever on the outside of the bulb. It's spring loaded and if it doesn't return back when you release it then it's sticking. I don't think this woudl cause a sudden drop in power. And of course it could be a bad pedal or connection or ground. Check along the wires to the injection pump for any bad connections or breaks. The car is drive by wire so a bad pedal sensor can cause strange symptoms. Any breaks along the wire can also cause strange problems.
 

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Discussion Starter #7
I had checked the EGR valve, and it's not sticking. It moves fairly easily and springs back just fine.

I certainly could have messed up during the fuel filter change, but we drove hundreds of miles after the change. I would assume that rules out getting the lines backwards. I replaced two o-rings on the T fitting on the fuel filter, blue on the inside and black on the outside if I recall correctly.

Where do I check for air bubbles? The only place I can find where it's clear is the T fitting on top of the fuel filter. I watched there for bubbles earlier and didn't see any, but the window is tiny and DIRTY. I will clean it tomorrow and check again... under load too... I just realized I had checked it only at idle.
 

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Sounds like fuel or ground to me. The timing is just a coincidence, probably related to the cold? A clear window on the T fitting? Mine is white plastic. Maybe the air is getting in at the fuel pickup at the tank?
 

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I don't think it's temperature related. While in Gatlenburg (just prior to this occurring) it was ~20 degrees. This happened and is continuing to happen over outside temperatures from 40 to 65 degrees.

I keep reading in the FAQ about watching for bubbles in the gas line and that they should be easy to see. However, I have no clue where this clear gas line is at. Can someone point me to it? :)
 

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They may be cloudy and some have black lines instead of semi-clear. In the above pic one fuel line is black and one is "clear". Some have reported a faulty o-ring in the fuel pickup in the tank which lets in air. It shows up during cold temps mostly. In any case, a few tiny specks is of no concern, a few big bubbles means that it's leaking air somewhere and causing fuel starvation. If you have 2 black lines, try taking some clear vinyl tubing and using that as a temporary way to check for air bubbles. If you see no air bubbles then there's no air leak in the fuel system. There could still be a problem with the pump. Get the codes scanned.
 

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The timing is probably not related to the cold temps, probably related to touching something recently, maybe the oil stain around the intake is a leak?
 

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Update...

I've dropped the car off with a new VW shop in town, euro-wise. They've got a nice shop and have been great to work with so far.

They cleaned the MAF sensor and the car mostly stopped sputtering. I say mostly because... well it still sputtered some but it trailed off and after a minute or two (warmed up?) it was fine.

I had the technician (and owner) in the car with me. They are going to do a little more on it tomorrow and see if they can resolve the issue. He suggested it might be the sensor or the EGR. I don't recall the logic on the EGR but it made sense at the time. Maybe it was fluttering...

They have a vag-com and are getting some codes from the computer. I am forwarding them the instructions for the EGR programming so they can undo that little bit of fun.
 
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