Bad EGR?

BRM: 2006/65k miles, Won't start, tons of smoke, codes inside, harness looks okay

2006 Jetta, 100hp PD engine, about 64k miles.

My wife's car started smoking heavily (black smoke, so too much fuel) and lost a lot of power on a hill today. This was a sudden event, the car has been working pretty well up until then (though the timing is a bit off so it idles roughly).

Now when the car is first turned on it has very little power, shudders heavily, and barely works. After going a couple of blocks (maybe half a mile) it goes into limp mode and is severely underpowered, but it goes. (update: now it doesn't go at all, it stalls seconds after starting).

VCDS (I liked the name VAG-COM better) reports the following faults:
000387 - Fuel Temp. Sensor A (G81)
P0183 - 000 - Open or Short to Plus - Intermittent
000257 - Mass Air Flow Sensor (G70)
P0101 - 000 - Implausible Signal - Intermittent
001027 - EGR Valve (N18)
P0403 - 000 - Malfunction - Intermittent

I searched the forums and the most similar thread to mine is this one:
http://forums.tdiclub.com/showthread.php?t=271894

This thread just ends with no resolution.

This led me down the path of checking the EGR. The first suspect thing is that the intake pipe wasn't properly seated, the top was cocked out by about 1/4". This means that it likely wasn't making a good seal. I checked inside and there is more oil than I'd expect to see, but it doesn't look heavily clogged. The oil + smoke from this recent failure can't be helping that.
I hooked up VAG-COM again and tried to drive the car. I got this graph:
http://i.imgur.com/n6P1oa2.png
red: engine speed
green: EGR (spec)
yellow: EGR (actual)
blue: EGR duty cycle

Since the EGR (actual) barely moves even when EGR (spec) is shooting up I'm guessing that this also points to EGR issues.
Is there a way for me to test the EGR with VAG-COM without running the car? I don't want to run the car without the intake pipe. I'd like to see if the EGR valve is moving.

You have two electrical errors and that EGR error is known to be electrical related. The below may not be your exact problem, but I suspect it's wiring common to all those components:

http://forums.tdiclub.com/showthread.php?t=331439&referrerid=22579

Thanks to your graph we know EGR is at least getting partial power/grounding... I guess it's not impossible for a bad EGR motor/solenoid/do-hickey to simulate a short and rob power to other components on that B+ leg. This can be tested by unplugging the EGR connector for a few days. What you're hoping for is all the errors to cease except for EGR.

Or, you have wire chaffing somewhere.

Thanks. That is an interesting theory, and a pretty easy one for me to check. It also sounds familiar, my 1998 Jetta TDI also had similar grounding issues (just with much different symptoms).

The wires on the fuel sensor are shorting intermittently and the car thinks it is -60 C. The wire entering the fuel sensor connector are usually crossed and could be shorting.

I'll check that. Could that really be causing all of these associated issues?

still no luck

I did find a wiring harness chafe problem at the fuel temp sensor. I fixed it. That got me to check the rest of the wiring harness (anything under split loom), and it all looks okay.

I redid all of the grounds, still no luck.

I checked the ASV operation by starting it with the manifold disconnected. The valve is closing slightly, but not very far. The car catches for a second, then stops and there is black exhaust everywhere (including coming out of the air intake).

At this point I'm ready to give up and have it towed to the dealer, unless someone can recommend a good TDI Guru in North Seattle. The one that people seem to like is ZahnTech over in Redmond, which would be an expensive towing bill.

I miss the ALH.

Too early to give up. Now that chafe repaired what codes are being set? Have you checked both fuse boxes for blown fuse?

Did you test the ASV without starting the car? Just turn key to on and peek inside the intake. Should be closed when key off and open when on. More importantly when key moved back to off the butterfly valve should cycle open and closed a few times. What you're testing for is full range of movement. Based on your codes I don't suspect ASV. Apologies if this not new info.

I think the answer lies in black smoke coming out the intake. Most likely source is EGR valve, and it's not utilized until motor at/near operating temp. May be stuck open; even a little will choke the motor.

I couldn't get the engine to stay on long enough to throw any codes.

I don't think the ASV is working then. It is always open, I just see it pivot about 5-10 degrees.

This is going to sound like a very stupid question, but where is the EGR valve on the BRM? Is it is behind and lower than the ASV?

It is the next component down the flow path to the intake. Right beside the ASV.

The ASV is normally open; it closes only when the engine is shutting down, then it opens back up when it sees zero rpm.

It can throttle as part of EGR operation.

Look for a PM, Alex, I will send you a thin metal EGR block off plate for testing. Insert it where the EGR line from the cooler connects to the EGR valve right at/under/below the intake pipe.

Set your torsion (mechanical timing of cam to crank) at +1.0 to -1.0. Be wary if it stays always at zero, never moving at all, as this is a default value that can be substituted without warning if the cam and crank disagree too much. If it is showing a 0.0 value, blip the throttle (logging a .csv file in the Turbo - fast speed - mode if available) to see if the value momentarily goes to +.5 or -.5; this would show it was an actual live value, not a substituted value.

Also, I would not hesitate to operate the engine with the ASV off and or the EGR off, for a short test. I do it whenever I feel it is needed. Be ready to close off the intake in the event of a runaway, but this is very unlikely.

Thanks Dan, that is all helpful information. I realize now for years that I've gotten the ASV and EGR confused, mostly because I've never had to deal with them (4 TDIs and we've never had intake clogging issues).

Do you have a drawing of the plate? I have a CNC mill and could make one in my basement shop. That would save time.

thanks,
alex

No drawing.
It might be fastest for you to pull out the gasket at that joint and use it as a template. I did put a handle or tab on it, so that I could maneuver it easily. I think the ones I have were made out of .042 stainless steel.

They were given to me for helping someone troubleshoot their TDI, so all I know about them is what I can see.

Dan

http://forums.tdiclub.com/showthread.php?t=369509 has some drawings in it.
The ALH flange is the same as the one on your EGR valve. In fact both the ALH and the BEW flanges are all the same size on both ends of the system.

The flange on your exhaust manifold feeding the EGR cooler is smaller, however.

I added a handle on mine, and they are thin and strong, intended to sandwich between two strong surfaces, for troubleshooting, not for permanent block off with removal of the existing pipes and flanges.

Thanks Dan. I wrote you a PM before seeing this, so you can disregard some of what is there. I'll make my own blocking plate and let you save yours for the next person who doesn't have access to a metal shop.

Hopefully I can do this tomorrow evening.

My wife grew tired of driving my old POS car and heard my frustration yesterday and had it towed to a mechanic. I think everyone is right, it'll be the EGR.

Thanks for the help. This is the first time in a long time that I've given up and had someone else fix it, but given our busy week it's probably the right decision.

I am dealing with similar issues, 207k miles, 2005.5 Jetta. EGR malfunction 3-4 times a day causes the car to go into limp mode, have to pull off the road and shut it off to reset it. I have replaced the EGR valve and it didnt fix it, so I am convinced it is wiring. The egr malfunction sometimes triggers an O2 sensor code, replaced that too, still has the problem.

Does anyone know how to just bypass the wiring harness and run new wires from the egr valve to where ever they need to go? I'd really like to try that, and it may help here as well.

Please let us know what you find is the cause.

I am coming to the party late.
Have both of you checked your cam?
As the cam fails, the injector lobes start opening the intake valves during the power stroke. This causes exhaust smoke out the inlet, popping noises, and low intake air flow which often causes a poorly worded "EGR flow too low" DTC.

I replaced my cam at 140K miles, I have checked it since then and all is still good.

I haven't checked the cam. It's on my list for the upcoming timing belt change. It seems very early for cam wear failures (we're at 64k miles) and it seems unlikely to cause a sudden failure. The car literally went from running great to big plumes of smoke the same day.

jcracing: I'd check the EGR cable near the plug and around the split loom for chafe. The split loom that VW used is very sharp. I spent part of last night checking most of my connectors and putting extra layers of tape between the split loom and wires to avoid chafe issues.

I checked the wiring within about 6-8 inches of the EGR plug, then lost it as the wires went into larger looms. I couldn't find any problems near the connector, but to rule out wiring, I would prefer to snip the wires near the plug and run new wires along the firewall to where ever they need to go, but I don't know where they terminate...

Does anyone have any pictures showing where the EGR valve wires terminate so I can try this bypass?

I'm pretty sure they go into the main loom that is under the air box. You should be able to find the same wires there and identify them by color.

I didn't chase that wiring loom beyond there to see where it goes next.

It was the EGR. New one in and the car is running nicely.

jcracing said:

I checked the wiring within about 6-8 inches of the EGR plug, then lost it as the wires went into larger looms. I couldn't find any problems near the connector, but to rule out wiring, I would prefer to snip the wires near the plug and run new wires along the firewall to where ever they need to go, but I don't know where they terminate...

Does anyone have any pictures showing where the EGR valve wires terminate so I can try this bypass?

Click to expand...

I think it was oil hammer or dan144 that said the wiring harness is reasonably cheap. Might want to buy a new one and since wiring is know to be a problem it would be very handy to have a spare harness to reference.