Intermittent starting issue

JSJ27959

Active member
Joined
Oct 20, 2023
Location
Nags Head NC
TDI
2012 Jetta TDI
My wifes 2012 Jetta is having random start issues.
She gets up in the morning starts the car with no issues. Goes to work is there 8 hours comes out to start the car and is slow cranking and wont start.
She ran it down to the point that it wouldn’t crank anymore the other day. So I went and jumped. It drove straight to AutoZone. They tested the battery, the starter and the alternator and everything came back. Good. Drive home. Wake up the next morning started again, no issues. She goes to work. The next day it does the same thing.
The battery is dying during the day but not at night.
Just the weirdest stuff ive ever seen.
 

MrCypherr

Veteran Member
Joined
Sep 3, 2012
Location
Ontario
TDI
Mk6 Wagon
Check your grounds in the engine bay. More so, the big one that goes from the transmission mount spot to the body. If there is any corrosion, clean it and check for the other grounds in the area by the fuse panel as well.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Autozone battery checks are about as useful as my nipples.

Put a [good] voltmeter on the battery, and see where the voltage drops to during cranking. You probably have a bad battery.
 

Garrison

Veteran Member
Joined
May 7, 2017
Location
Charlotte
TDI
Stg 3 - 2011 JSW
Autozone battery checks are about as useful as my nipples.

Put a [good] voltmeter on the battery, and see where the voltage drops to during cranking. You probably have a bad battery.
Same instructions for the nipples too 🤣
 

JSJ27959

Active member
Joined
Oct 20, 2023
Location
Nags Head NC
TDI
2012 Jetta TDI
Check your grounds in the engine bay. More so, the big one that goes from the transmission mount spot to the body. If there is any corrosion, clean it and check for the other grounds in the area by the fuse panel as well.
I forgot to mention that already cleaned a bunch of the grounds. None of them really looked that bad. Also clean the connection at the starter cable. It had a little corrosion.
 

JSJ27959

Active member
Joined
Oct 20, 2023
Location
Nags Head NC
TDI
2012 Jetta TDI
Autozone battery checks are about as useful as my nipples.

Put a [good] voltmeter on the battery, and see where the voltage drops to during cranking. You probably have a bad battery.
I’ll give that a shot.
But still seems weird, that it only does it during a certain time of the day. But it’s just fine in the morning.
 

JSJ27959

Active member
Joined
Oct 20, 2023
Location
Nags Head NC
TDI
2012 Jetta TDI
I checked the voltage before starting it was 12.2 voltage dropped to 9.2 during the start.
it was a long crank. But eventually it started. Almost like the fuel is not there.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Yep, you need a battery.

Get one from the dealer... should be the 72Ah unit, the H6 size.

Nominal battery static voltage is 12.6v (6 cells, 2.1v each)

Normal cranking voltage permissible 10.5v

ECUs start wigging out around 9.6v, and the EDC17 Bosch ECU in your car for sure does not like low voltage, and they do not seem to work well with picking up proper CKP signal when cranking slow. Much less forgiving than the older diesels.
 

JSJ27959

Active member
Joined
Oct 20, 2023
Location
Nags Head NC
TDI
2012 Jetta TDI
Makes sense because i just went to autozone again and had them read the codes. I have a ton of electrical codes. Plus the battery read
only 69% this time. I just drove the car 8 miles to get there.

Current battery is 12v 72ah 380a DIN
640A EN
Lead calcium
Battery date 10/19
 
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JSJ27959

Active member
Joined
Oct 20, 2023
Location
Nags Head NC
TDI
2012 Jetta TDI
With the new battery it has the ability to crank long enough to start but the issue still remains.
First thing in the morning it fires right up. (40deg)

During the day the cranking time is twice as long maybe more. I just dont get it.
Like it is having to crank awhile to get the fuel pressure up.
I install a factory bosch inline pump two months ago.

I can hear the inline pump running too.
Any thoughts?
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
So it cranks good and fast now, just for a long time, correct? Once it does start, it starts and runs normally? If you shut the engine right back off, and start it again, will it start right up with no long crank time?
 

JSJ27959

Active member
Joined
Oct 20, 2023
Location
Nags Head NC
TDI
2012 Jetta TDI
After sitting all night it fires up the quickest. 2 seconds max.
But if i then take it for a drive then shut it off for 30 mins or more its cranking 6-10 seconds to start.

Yes runs normally after start.
 

JSJ27959

Active member
Joined
Oct 20, 2023
Location
Nags Head NC
TDI
2012 Jetta TDI
I also need to mention that I have a low flow egr code.
I cleaned it and it still remains.
A stuck closed swirl valve code.
I deleted the swirl valve this past weekend.
Also have a dpf code.
I know its cracked and i have the delete kit I need to install but i havent bought the tuner yet. . I havent got around to that yet.
Is this the possible cause?
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Nah, that's not any of it.

Fuel source? Anything changed recently there? Any additives put in it? Too much of an additive can do the exact thing you describe, I've had lots of customers mistakenly do that.
 

JSJ27959

Active member
Joined
Oct 20, 2023
Location
Nags Head NC
TDI
2012 Jetta TDI
No additives.

But I did pull the fuel rail to clean the intake a little over a month ago.
Also again last weekend for the swirl valve delete.
I was pretty meticulous about keeping everything clean trying not to get anything in the lines.

I guess i just need to get a vcds to really see whats going on.
 

rrgrassi

Veteran Member
Joined
Jul 31, 2006
Location
Royse City, TX
TDI
'06 Jetta TDI 5 speed
Our 2013 did that, except the alternator and battery checked out fine. When hot it would crank, and not start until the third try. Replaced the starter. Now cranks fast and short even after long drives.
 

MrCypherr

Veteran Member
Joined
Sep 3, 2012
Location
Ontario
TDI
Mk6 Wagon
Sounds like the starter was pulling more amperage than it was suppose to. Seen that on a few cars.
 

JSJ27959

Active member
Joined
Oct 20, 2023
Location
Nags Head NC
TDI
2012 Jetta TDI
I am about to delete this car it has $250,000 on it.
Im looking at the Malone stage .5 and stage 1.
I see the stage 1 has trans tuning is it worth it?
Im not doing it for power mostly just reliability. What tune would you choose?
 
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bigdog0u81

Veteran Member
Joined
Apr 2, 2012
Location
Hagerstown Md
TDI
2000 golf
I did the Malone stage 2 and rawtek deletes. Its a totally different car. But you will have to find someone to tune it most shops around me wouldn't. I got the loader box and did it myself.
 

JSJ27959

Active member
Joined
Oct 20, 2023
Location
Nags Head NC
TDI
2012 Jetta TDI
Ordered my tuner today from Malone.
They are 15% off right now.😃

Since changing the battery I have not had anymore
Starting issues.
 
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