2001 VW Jetta engine shakes on shutdown

[TobyBurk]

So I left my VW Jetta TDI sit for about a month in the winter due to covid-reasons, had to jump it to get it started, but it started up without hassle. Unfortunately, the battery is pretty much dead right now so if it's been running recently it'll start, but any longer than a few hours and it's dead. I took it out for a drive yesterday and it threw an orange engine light and the RPMs shot up to about 2400RPM at 40km/h. When I eventually parked it and shut off the engine I heard the engine shudder on shutdown. EDIT: I've figured out the engine light thing, still not sure why it's shaking on shutdown. See my next post.

I know the battery is dead, but I'm wondering if anything else can be causing me issues? I haven't had a chance to check the ASV because it's been raining, but could all of this be caused by just the dead battery or are there additional areas to be checking right now?

 

[TobyBurk]

ASV valve looks like it can move easily enough. Dropped in a new battery, but still high RPMs and shaky shutdown. The engine code says the output speed sensor on the transmission is not working, so that explains the high RPMs. Any suggestions on the shaky shutdown?

 

[Vince Waldon]

You were able to watch the ASV consistantly closing during shutdown?

 

[TobyBurk]

You were able to watch the ASV consistantly closing during shutdown?

I'm only one man, so the best I could do was make sure it felt movable while the car was running and after shutdown. There is quite a bit of dirt built up around it though (possibly oil or grease?)

 

[Vince Waldon]

The only way to know if the anti-shudder valve is working is to watch it when it's supposed to anti-shudder...ie... close briefly right after the ignition is turned off.

It can be free-to-move but not being actuated properly, which would cause your exact symptoms.

 

[TobyBurk]

The only way to know if the anti-shudder valve is working is to watch it when it's supposed to anti-shudder...ie... close briefly right after the ignition is turned off.

It can be free-to-move but not being actuated properly, which would cause your exact symptoms.

I suppose I'll have to set up a camera to watch it. If it's not closing, what's the chain of parts I should be checking/testing, and how long can it be like that before I have bigger problems?

 

[Vince Waldon]

It moves via a vacuum actuator and is activated by a control solenoid bolted to the firewall. Just follow the black braided vacuum lines.

Pretty straightforward to troubleshoot, but you'll really need someone else keying the ignition for you so that you narrow down what's not working during the brief period it's supposed to. Or a vacuum gauge and/or multimeter/test light rigged so you can see it from the drivers seat.

If it's simply a actuator or control solenoid problem you can drive forever, but if the real reason it's not working is upstream at the vacuum pump or a vacuum leak somewhere then your turbo is also potentially being affected as well, and that can allow the vanes to soot in place... $$$.

 

[TobyBurk]

It moves via a vacuum actuator and is activated by a control solenoid bolted to the firewall. Just follow the black braided vacuum lines.

Pretty straightforward to troubleshoot, but you'll really need someone else keying the ignition for you so that you narrow down what's not working during the brief period it's supposed to. Or a vacuum gauge and/or multimeter/test light rigged so you can see it from the drivers seat.

If it's simply a actuator or control solenoid problem you can drive forever, but if the real reason it's not working is upstream at the vacuum pump or a vacuum leak somewhere then your turbo is also potentially being affected as well, and that can allow the vanes to soot in place... $$$.

Well if the problem's upstream it's going to be an expensive fix anyway as I'll have to start tearing the whole darn thing apart (and I'll have to take it to a shop for that, I don't have the equipment)

It pains me to say it, but with my health problems I need something that'll carry me the ~100km trip to the doctor's office once a month. This is literally the only car I've ever owned, but I may have to part it out and look at replacements.

I greatly appreciate the advice.

 

[Vince Waldon]

Don't give up on 'er yet... .the vacuum system is pretty simple and most of the time the issue is a leaking vacuum hose connection at one of the many barb fittings. The hose is braided cloth over rubber and will rot out over time. Replacement hose is dirt cheap.

 

[TobyBurk]

Quick update on this: I had the engine light read and the issue was just a broken sensor. While the engine light was being read I had them check the vacuum system and they said it was fine, but also told me that the car had no pickup because the turbo was ceased.

Now, I can't be convinced that the car ever had turbo, as I can't recall the last time it had a 0-60 in under 20 seconds. Anyway, the vacuum system (I'm told) is okay, so the issue must be elsewhere.

Thanks, all.
-Toby.

 

[greengeeker]

Quick update on this: I had the engine light read and the issue was just a broken sensor. While the engine light was being read I had them check the vacuum system and they said it was fine, but also told me that the car had no pickup because the turbo was ceased.

Now, I can't be convinced that the car ever had turbo, as I can't recall the last time it had a 0-60 in under 20 seconds. Anyway, the vacuum system (I'm told) is okay, so the issue must be elsewhere.

Thanks, all.
-Toby.

Toby - the turbo is controlled by the vacuum system. If you have a vacuum leak you'll have a) low boost b) shaky shutdown due to inoperable ASV.

For me, the telltale sound I listen for on a vacuum leak is the ASV itself. You should hear the ASV audibly open back up ~2 seconds after the engine has shut down. If you don't, you need to check for vacuum leaks (most common) or a ruptured diaphragm on the ASV.

 

[csstevej]

Just had this on daughters NB 2000.
For us it was the vacuum line fell off the barb as the hose was cracked and wouldn’t stay on…..also the hose coming from the vacuum ball to the tee had worn a hole where it was routed under the vacuum pump. Replaced hose and cut off split end and all is right in the world…..just my .02 .