2003 TDI Jetta "diesels" after shut off

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TractionAction

Active member
Joined
Jun 15, 2009
Location
Brentwood CA
TDI
Had 2010 Jetta
I have kinda an odd problem with my 2003 Jetta, 181k miles. In some cases not all, the engine will "diesel" maybe 1 or 2 revolutions after I turn the engine off. This just started to happen, the engine does run as expected. Any thoughts on this?
 
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tditom

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Sep 5, 2001
Location
Jackson, MI
TDI
formerly: 2001 Golf GL, '97 Passat (RIP) '98 NB, '05 B5 sedan
Sounds like your anti-shudder valve may not be right.
 
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fossill

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Canada
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Golf
Or he's stepping on clutch while turning key off. That keeps it from working too
 
Vince Waldon

Vince Waldon

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Apr 25, 2009
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Edmonton AB Canada
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2001 ALH Jetta, 2003 ALH Wagon, 2005 BEW Wagon
Yup, your car has an anti-shudder valve (or ASV) bolted to the intake manifold to prevent this very thing... so that would be a good place to start.

If you search on "shudder valve" you should find lots of threads, pictures, etc.
 
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fossill

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The Bently manual gives a description of when its operational, under what circumstances and for how long in Sections 1 to 3.
 
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FlyTDI Guy

FlyTDI Guy

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Nov 3, 2001
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PNW
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'01 Jetta GLS
I'm thinking this has not been my experience. Change-over valve works whether clutch in or out. I see no reference in my Bentley about clutch/change-over cooperation. Only when it works and for how long.

When the ECM receives the signal to shut down, a signal
is sent to a flap valve mounted in the intake tract. This
valve, known as the intake manifold change-over valve,
closes and blocks the flow of air to the still-turning engine.
Blocking the flow of air during the shut-down cycle reduces
the abruptness associated with stopping a diesel engine.
Click to expand...
The intake manifold change-over valve
is a flap valve that closes for approximately
3 seconds when the engine
stops, blocking the air to the engine.
This reduces the suddenness of the diesel
engine shut-down. The valve reopens
once the engine has stopped.
Click to expand...
I guess I should all, it's quite apparent when it's not working. I recently scanned a buddy's car and, on shutdown, I immediately noticed it ran on longer than it should. He had massively low vacuum due to a worn vacuum pump outlet and the change-over valve wasn't shutting properly. I shut my car off w/clutch down all the time and it stops clean. Always has. I'd be interested to see the source if it indeed works differently.
 
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T

TractionAction

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Jun 15, 2009
Location
Brentwood CA
TDI
Had 2010 Jetta
Well I finally tore into this issue and have ruled out the following:
1) I tested the shutter valve and it moves freely.
2) I briefly connected a live vacuum line to the shutter valve and it closed, killing the engine. OK, that works.
3) The solenoid that allows vacuum to pass at engine shut off was tested and does function. Tested via connecting to 12v power.
4) Fuses where checked, none are blown.
5) Power to the solenoid was checked via voltage meter, no voltage detected at shut off.

At this point I'm thinking it's Relay 109, I have the gray version. Does this make sense? Are there any other places to check?
 
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whitedog

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Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
FlyTDI Guy said:
He had massively low vacuum due to a worn vacuum pump outlet and the change-over valve wasn't shutting properly.
Click to expand...
This was my first guess. Check your vacuum supply into the solenoid valve, then if it's low, work back through any check valves and tees and whatnot.
 
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TractionAction

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Brentwood CA
TDI
Had 2010 Jetta
whitedog said:
This was my first guess. Check your vacuum supply into the solenoid valve, then if it's low, work back through any check valves and tees and whatnot.
Click to expand...
I checked the vacuum by bypassing the solenoid valve using the same vacuum line that goes to the solenoid. Once connected, the shudder valve closed and the engine shut off right away.

I'm thinking the solenoid is not getting any power to activate when the key is turned to the off position. Otherwise, the engine runs great.
 
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RacerTodd

RacerTodd

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Kirkland, WA
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2001 Golf TDI
I had an intermittent "dieseling on" situation. Was intermittent for a while then dieseled on at every shut off.
Turned out the wiring to the N239 valve (which controls vacuum to the ASV) had chaffed on the EGT probe wiring, meaning the ASV wasn't getting actuated on every shutdown. The wires are in a sheath, but the vibration against the probe wiring chaffed right through the insulation.

Might we worth easing the wires to the N239 valve out of the sheath and seeing if there is any damage.

I diagnosed by checking for vacuum at the ASV on shut down. When I didn't see any I checked for vacuum at the N239, I had good vacuum when engine was running. Then I hooked up my multi meter to the N239 connector - and saw no voltage when the car was turned off. Tracing the wires lead to my finding the chaffed wires.
 
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whitedog

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2004 Jetta that I fill by myself
OK, so you have good vacuum. We can cross that off the list. Next up is Todd's suggestion about the worn wires. Check upstream from the connector. IIRC, Oldpoopie had a thread about it a few years back, complete with pictures.
 
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TractionAction

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Location
Brentwood CA
TDI
Had 2010 Jetta
Some progress.....I pealed back the plastic tubing for the solenoid wires and sure enough the wires where frayed and broken.
I soldered them back together, reconnected and still no luck.
My voltage meter indicated 3 volts at the connector while the engine was on. But when turned off, the voltage needed to trigger the solenoid did not occur.
The voltage just dropped to zero when the key was turned off.
I also replaced the vacuum line to the solenoid.
Any other thoughts?
 
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whitedog

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2004 Jetta that I fill by myself
The first thing I can would do in that situation is check my work. Maybe check for voltage just before the repair. After that, I would check that putting voltage to the solenoid makes it work.
 
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TractionAction

Active member
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Jun 15, 2009
Location
Brentwood CA
TDI
Had 2010 Jetta
Yes, the solenoid works great and closes the shutter valve. Now the car runs but diminished power and the CIL is on. Look's like a long afternoon of trouble shooting...FYI: The shutter valve is open during my test drives.
 
RacerTodd

RacerTodd

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2001 Golf TDI
The wiring for the N239 solenoid is real simple. If you have a Bentley manual, turn to page 97-692, section number 66/8.

The purple/grey wire goes directly back to terminal 81 on the ECU. The ECU grounds this wire to activate the N239 solenoid. That could be checked for continuity.

The yellow/black wire is the 12v supply. It is connected inside the wiring harness to the yellow/black wires on the N75, N18 and MAF sensor. Those all go back to Fuse 34.

So, I assume you should see battery voltage on the yellow/black wire when the ignition is on. BTW, the yellow/black in Terminal 1 on the connector, same as on the other 3 components listed above.
If you're not getting 12v at the N239, the issue could be farther inside the harness where all those yellow/black come together.

Your 3v seems low, I assume that should be 12v. When the ignition is turned off you should see a ground signal on the purple wire (to activate the solenoid), with the purple staying at 12v.
 
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whitedog

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TDI
2004 Jetta that I fill by myself
RacerTodd said:
The wiring for the N239 solenoid is real simple. If you have a Bentley manual, turn to page 97-692, section number 66/8.

The purple/grey wire goes directly back to terminal 81 on the ECU. The ECU grounds this wire to activate the N239 solenoid. That could be checked for continuity.

The yellow/black wire is the 12v supply. It is connected inside the wiring harness to the yellow/black wires on the N75, N18 and MAF sensor. Those all go back to Fuse 34.

So, I assume you should see battery voltage on the yellow/black wire when the ignition is on. BTW, the yellow/black in Terminal 1 on the connector, same as on the other 3 components listed above.
If you're not getting 12v at the N239, the issue could be farther inside the harness where all those yellow/black come together.

Your 3v seems low, I assume that should be 12v. When the ignition is turned off you should see a ground signal on the purple wire (to activate the solenoid), with the purple staying at 12v.
Click to expand...
According to what Todd wrote, check voltage on terminal 1 on the N75, N18 and MAF sensor. They should all read 12 V with key on. If they don't, then you have something common that is causing this. But if the car runs perfectly otherwise, it's doubtful, but still a cheap, quick check to verify.
 
4

[486]

Top Post Dawg
Joined
Mar 1, 2014
Location
MN
TDI
02 golf ALH
While doing all this be sure you're putting the vacuum lines on the solenoid valve the correct way, one of the barbs is vented and the thing'll leak enough vacuum to affect VNT actuation if hooked up wrong.
 
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TractionAction

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Location
Brentwood CA
TDI
Had 2010 Jetta
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