Rough Idle and Smoke

I have a 2000 Jetta TDI with 225K miles on it. I recently gave it to my daughter to take to college.

She was driving it the other day when it suddenly began to run very rough. She pulled over fairly quickly, and I went and pulled it home on a trailer. She had driven over 100 miles since her last fuel fill up.

Here are the symptoms: Very rough operation at any speed. White/Gray smoke. When I initially checked the codes it had both a P1556 and P0301. I cleared them and have been unable to replicate them, as I don't want to drive it much.

What I've done: unplug the MAF sensor, with no change in symptoms
cracked the fuel fitting on cylinder one, with fuel present
drained the fuel filter

The timing belt was changed 20K miles ago, and appears to be okay.

I don't have a vag-com to do further detailed investigation.

Any suggestions on where to go from here?

Thanks

Check the intercooler for oil, do not start or drive it any further until you do.

Smell the stuff you drained out of the filter. Or sniff the fuel fill nozzle with cap removed. See if you detect the odor of gasoline.

Was oil level low? That could indicate turbo seals leaked, intercooler got filled, and engine ran away.

Ask her if it ever acted like it "took off on its own".

May also want to check the IP/cam/TDC timing.

jjenkins334 said:

The timing belt was changed 20K miles ago, and appears to be okay.

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who replaced it? Are there any paint marks on the cam gear, injection pump gear, belt? Take a close look at your timing belt tensioner - do the marks line up? Is the arm of the tensioner in the correct slot (directly underneath the cam gear)?

greengeeker said:

who replaced it? Are there any paint marks on the cam gear, injection pump gear, belt? Take a close look at your timing belt tensioner - do the marks line up? Is the arm of the tensioner in the correct slot (directly underneath the cam gear)?

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All very good points. Check them out.
Also, how many gallons did she add 100 miles ago?? Half a tank of diesel topped off w/gasoline by accident can make for a VERY bad running TDI. Take/get a sample of the fuel and compare it to diesel fuel.
What were the VCDS codes description (P1556/0301)?? I don't know them w/o looking them up.

Thanks for the responses. I'll try to dig into these tonight.

P0301 is "Cylinder 1 Misfire"
P1556 is "Charge Pressure Contr. Negative Deviation"

I did the "smell test", and the fuel smells strongly like diesel, with no gasoline smell. I'll try to siphon some fuel out of the tank and check it out. My daughter swears she put diesel into it and not gas. My other daughter made that mistake a few years ago, but realized it before she started it. It took me a while to siphon all of the gas out!

I have a friend who did work on diesels years ago, and he suspects that cylinder one is not firing. I have a feeling this could get expensive before all is said and done!

Check turbo "charged air" ducts. Sometimes they can come apart at a joint. Loss of boost, smoke, CEL.. Maybe a cheap fix.

puter said:

Check the intercooler for oil, do not start or drive it any further until you do.

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The intercooler does have a thin coat of oil in it, at least at the output of the connection to the boost intake air line. What would this be an indication of? The oil level on the dipstick has not dropped, and my daughter says there was no runaway condition before it started running rough.

Any input would be GREATLY appreciated!



Thanks,

Ok..so far: No runaway, oil level good, no gasoline, #1 misfire code, not much oil in intercooler, smoke, run rough.... Might want to check under cam cover to look at #1 cam lobes. Not too hard to do and no parts needed.

Ski,

You're right on the money. I pulled the cam cover right after I posted the last response, and found cylinder one had eaten a valve. I suspect that it probably contacted the piston as well, as the damaged valve is recessed into the seat a good ways.

Is this normally a wear and tear thing, or is it likely something else broke and caused this damage?

Thanks,

Cams do wear on these, taking the cam follower with it. Not many fail, just some. Sometimes the damage is limited to the cam and followers, which can all be changed out quite easily. If the tip of the valve stem or the cylinder head casting (aluminum) is damaged, then the cylinder head must be pulled for repair.

Are you sure of your nomenclature? The valve and seat are only visible if you have pulled the head. Have you done that yet?

Can you post photos of the #1 lobes and followers?

jjenkins334 said:

Is this normally a wear and tear thing, or is it likely something else broke and caused this damage?

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it is likely a botched tb job (see post #4)

I'm sure I'm misusing terminology. The lobes are definitely damaged, and the right circular piece (cam follower?) for cylinder one that goes into the head has it's top broken off. Sorry for not being more technical. The top of the head in front of the cam is damaged as well.

I'm trying to figure out how to make the pictures I took small enough to upload. Right now I get an error message stating they're too large.

I used a different mechanic to do my last timing belt change. Looks like that was a mistake!

Here's the damage:


Any opinions?

Here's one more, a little closer up.

off with her head! contact franko6 to get you rolling on a rebuilt head and tb kit.

greengeeker said:

off with her head! contact franko6 to get you rolling on a rebuilt head and tb kit.

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Yep. And I assume Nick was referring to the TDI's head...although the "mechanic" that did the TB may be a candidate as well.