Intermittent Random Hard Start Problem 2004 Jetta

Mawcus

Veteran Member
Joined
Oct 5, 2012
Location
Bellingham, WA
TDI
2004 Jetta TDI BEW PD 5 Speed
2004 Jetta 5-Speed 180k miles. Ive been having random hard start problems. Really random. Seems to be no consistency as to when it will take a long time to start. Recently there have been some cold frosty mornings and it fires up right away. Takes longer to start after its warmed up and I go somewhere and try to start it again. Sometimes just a few cranks and other times 10-20 seconds of cranking. I suspect air is getting into the fuel lines but haven had a chance to install new lines. I guess it could be timing related. There really is no distinct pattern or consistency when its hard to start but very rarely does it fire up at the first bump of the key as it should. I get everything from a second or two of cranking to having it crank for 10 or more seconds and having to try 2-3 times before it fires up.

Cam is good, new stage 2 cam a few years ago. In tank lift pump has been recently replaced. New alternator, pulley and voltage regulator. Serpentine belt and tensioner is new. Battery is new.

Any info is appreciated.
 
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joep1234

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Jan 2, 2014
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NC
TDI
former '04 Beetle TDI, now 2x '15 Audi Q5 TDI's, 2007 Dodge Ram 4x4 6.7
Have you scanned it? Look at you temp sensor with the scanner. It may be out of whack. Also is your starter spinning it up to speed every time. The ECM won't start fueling until it hits 250 rpm.
 

Mawcus

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Oct 5, 2012
Location
Bellingham, WA
TDI
2004 Jetta TDI BEW PD 5 Speed
coolant temp sensor was new 2 years ago. tach works when cranking. fired up instantly this morning in sub freezing temps
 

Mawcus

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Joined
Oct 5, 2012
Location
Bellingham, WA
TDI
2004 Jetta TDI BEW PD 5 Speed
Well, got around to replacing the fuel lines and I’m still having the same starting issues. No different than before replacing lines. Not sure what to check next. Need to check timing but dont have VAGCOM. Also considering replacing crankshaft speed sensor. Until I check the timing and replace crank sensor I’m stumped. This vehicles has not had any off the glow plug recalls done so i guess thats an option too but during cold starts first thing in the morning it instantly fires up. The colder the better. Im baffled
 

Mawcus

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Joined
Oct 5, 2012
Location
Bellingham, WA
TDI
2004 Jetta TDI BEW PD 5 Speed
Is it possible that it fires up great when cold because of the glow plugs but takes a long time to start when warm because the glow plugs dont kick in.
 

AndyBees

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Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
Even though the in tank pump has been replaced recently, it may be coated with soot. You should be able to hear it when you first turn on the ignition.
 

mrowens33

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Aug 29, 2012
Location
Brookfield
TDI
2004 Jetta sedan slushbox, 2004 Jetta wagon manual( my Noble Steed)
http://forums.tdiclub.com/showthread.php?p=5372227#post5372227

This post about glow plugs might be helpful. I put new 7 volt glow plugs in with a ECU tune and it took care of my hard starting problem. It is a relatively cheap thing to try since your car didn't have either of the recalls done in the past. You can buy them for around $100 on ID parts but you would need to have a tuner or the dealer update the ECU.
 

Mawcus

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Joined
Oct 5, 2012
Location
Bellingham, WA
TDI
2004 Jetta TDI BEW PD 5 Speed
Started car this morning. Fired up pretty quick. One little stumble then it fired up. Noticed that the tach didnt move. Turned car off. Started again instantly but still no movement on the tach. Turned it off and on few more times and it was the same. No tach but started instantly. Drove 20 minutes to park amd ride for work. Turned car off then started it. Took a long time before it started and it stumbled a little bit. This time i did notice the tach move several hundred rpms or so. Started it again. Long time cranking and tach was dead then jumped up to where it was before. Maybe this is an indication of a bad crankshaft speed sensor. Should the tach move during started ups every single time and to the same rpm level?
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
Seems like it should.
The fact that it starts good cold makes me interweb guess it's not air in fuel. Doesn't sound like glow sticks either.
I think you are now on the right track.
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
Yeah, should show about 250 RPMs while cranking during start-up!

Remove the CSS and clean it ... might solve the problem.
 

Mawcus

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Joined
Oct 5, 2012
Location
Bellingham, WA
TDI
2004 Jetta TDI BEW PD 5 Speed
Well ordered a new Crankshaft Sensor and installed it last night. Car started up great several times over and over. 1-2 seconds of cranking max. the glow plug lights were blinking for several seconds until i turned the key for the first time but once i turned the key it fired right up and the glow plug lights went out. CEL kicked on too then went away once it was running. didnt have time to do a test drive last night and didnt want to deal with any potential issues or get stranded on friday night. started it up this morning feeling pretty good about solving the starting problems. fired it up and it didnt start right away. cycled the key a few times, tried to start again. seemed to spit a little and misfire. Then it started. started it a few more times and it consistently took 2-3 seconds to fire up. Not too happy. drove it around the hood till it warmed up then parked it. started it again several times and it consistently took 2-3 seconds to start. last night it damn near started right away. thats why i'm not too happy about how it starts. tach seems to be responding when its cranking which it wasnt doing before. I guess i will c how it starts throughout the day. as usual I thought I had it figured out last night when it fired up like it should but i guess not...
 

Mawcus

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Joined
Oct 5, 2012
Location
Bellingham, WA
TDI
2004 Jetta TDI BEW PD 5 Speed
Also getting a G40 Camshaft Postion sensor fault code when I scan with VCDS Lite. clear the code and it comes right back. CPS has been replaced recently so I don't get it.

Been cruising around town doing stuff and it still has longer than normal starts. its behaving differently than before I changed the Crankshaft sensor but still taking too long to start. stumped and pissed
 
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joep1234

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Jan 2, 2014
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NC
TDI
former '04 Beetle TDI, now 2x '15 Audi Q5 TDI's, 2007 Dodge Ram 4x4 6.7
Did you use a OEM/VW or an aftermarket sensor? These cars can tell the difference. A lot of the aftermarket parts are made in China. Just crap. Even NAPA is getting a lot of their parts from over there.
 

JB05

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Oct 20, 2005
Location
Il.USA
TDI
Golf,2005,anthracite blue
I bought my new CPS from a reputable vendor and was a bit disappointed that it does not have any Audi/VW markings. I just replaced it a couple of days ago and so far it's been good. I had inadvertenly disrupted the cable to the old sensor when I replaced my t-stat and the car would not start. After repositioning the cable it would start but stall in traffic.
 

Mawcus

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Oct 5, 2012
Location
Bellingham, WA
TDI
2004 Jetta TDI BEW PD 5 Speed
It was listed as a OEM/VW part. Bag that it came in said “origin spain”. It was a little different than the one i replaced. Had a hard time getting it all the way in. Snugging up the one bolt wouldnt pull the whole thing flush where it sits. Had to tap on the back of the sensor “lightly” with a dowel rod and wrench to persuade it to sit flush. Maybe that screwed it up.
Gonna check timing-torsion with vcds lite. Ive checked before and its reading 0.0. Might be out of range to register so i plan on adavancing it a little until the change shows up. Hopefully that will improve strating.
 

Mawcus

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Oct 5, 2012
Location
Bellingham, WA
TDI
2004 Jetta TDI BEW PD 5 Speed
Tried to advance timing but torsion still read 0.0 Still have the G40 No Signal Fault so I'm figuring I've got a chaffed wire or something similar going from the harness to the ECU. Cam Position sensor is not that old (replaced in the last year or so) so it should be good. Plan on testing cam position sensor and the harness to ECU with multimeter and hopefully isolate the problem. I'm guessing and hoping that a wire is chaffed and that will be the solution...
 

Mawcus

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Joined
Oct 5, 2012
Location
Bellingham, WA
TDI
2004 Jetta TDI BEW PD 5 Speed
Testing a BEW Camshaft Position Sensor

Tested the cam position sensor harness with multimeter and it checked out according to the testing methods on a thread i found here. Tried to test the cam sensor itself but got no reading at all so i figure its toast. Replaced it less than two years ago. Then I remembered i had the old cps still. Dug it out and tested it and got some readings on the ohn meter. The info ive been using was based on a thread for BRM. Ive got a BEW so maybe the info is different because the numbers didnt quite fall into range (maybe old one is toast too). Couldnt get any readings with “newer” sensor. Got some readings with old sensor so i decided to plug in old sensor to see if the G40 No Signal fault would go away. Well it didnt. Im using VCDS Lite and got the same fault codes as the newer cps. I guess both are toast. I thought i was gonna find a problem in the harness going to the ECU and then be able to find a chaffed or broken wire but as far as i can tell with the multimeter it seems fine. I guess my next step is to buy a new CPS, plug it in and see if No Signal code goes away. I hate to throw parts at a problem but i think I would rather drop another $75 bucks on a CPS before i admit defeat and take it to a shop.

Ive looked all over the interweb and cant find exactly how to test a BEW camshaft position sensor or what values a good one puts out. Found info for BRM and maybe its the same. If anyone has info specifically for the BEW I would be very grateful.
 

tjpeterson96

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Joined
Aug 1, 2014
Location
Winter Garden, FL
TDI
04 bew jetta
I am having the same issue. intermittent hard start and CEL with codes for cam sensor AND crank sensor. I am going to trace the wiring tomorrow and see if the wires are frayed somewhere
 

Mawcus

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Joined
Oct 5, 2012
Location
Bellingham, WA
TDI
2004 Jetta TDI BEW PD 5 Speed
I remembered that i had the original cam sensor that i had replaced. Put the original back in and it fixed all starting problems. Before i ordered a brand new sensor I figured i would try the old one. Old one worked fine. I had mistakenly replaced it due to a fault code I was getting for the cam sensor. I was getting the code because of a faulty cable between the battery and alternator. There wasn’t enough voltage going to the cam sensor and it triggered a code.
 

Mawcus

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Oct 5, 2012
Location
Bellingham, WA
TDI
2004 Jetta TDI BEW PD 5 Speed
Check the cable between the alternator and the battery. A bad cable or bad connection can cause a problematic voltage drop. Also check for any loose connections on top of the battery. Had a problem with the little secondary bracket on the positive cable. The nut was tight but the bracket still had a wiggle in it that was creating a voltage drop. There was a small gap that I filled with a washer that snugged it all up. Voltage drop went away.

These voltage drops caused a fault code for cam sensor and crank sensor. I replaced a lot of sh!t that i probably didn’t need to.
 
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