Cold-Start Problems .... STILL!!!!!!

LindenKeith

Member
Joined
Dec 21, 2004
Location
Linden, Michigan
TDI
99 VW Beetle - 67 VW Beetle
I am still having cold start problems. If the temp is below 25 degrees F. The glow plugs warm up and the car starts right up! If the temp is above 25 Degrees F the glow plugs do not warm the engine and the car takes quite a while for the car to start. I have replaced the glow plugs and the Coolant temp sensor and it is still having the same problem. If I unplug the coolant temp sensor the car starts right up. Any suggestions?
 

MOGolf

Top Post Dawg
Joined
Jun 27, 2001
Location
underneath something
TDI
2001 Golf GLS TDI Reflex silver, rough road suspension and steel skid plate, 2004 Passat Variant, Candy White, rough road suspension and geared balanced shaft module, and much, much more. 2016 LR RR HSE TD6, 2019 Jaguar I-PACE
Any possibility that the wires in the connector are shorting together when plugged in to the sensor?

Also need to check the start of injection timing.

Perhaps meet up with Jetaah (near Fowlerville) and have him check the sensor and timing readings with VAG-COM.
 

rdkern

Top Post Dawg
Joined
May 21, 2004
Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
So - we have below 25 works well, above 25 doesn't. Pull temp sensor and glow plugs work and starts well.

Since you've changed the temp sensor and it didn't do anything, it's tough to blame the new sensor, but where else could it be? Please provide all details, such as the original problem, each step taken and the results. Perhaps a more complete listing would be helpful.
 

Bob_Fout

Oil Wanker
Joined
Sep 5, 2004
Location
Indiana
TDI
2003 Jetta - Alaska Green (sold) / 2015 GTI 2.0T
Might try *another* sensor. Wouldn't be the first time a new part was DOA.
 

LindenKeith

Member
Joined
Dec 21, 2004
Location
Linden, Michigan
TDI
99 VW Beetle - 67 VW Beetle
ok... Original problem is the same problem. The glow plugs do not warm if it is warmer then 25 degrees. I thought it was the glow plugs themselves. But, that was before I found this website. And Before I associated the temperature with the problem. After I replaced the glow plugs I still had the same problem. I then put a post up and the majority thought it was the coolant Temp sensor dying. I rreplaced that and today I still have the same problem. This morning it was 32 and I had to really crank it to start. This afternoon it was 54 and still had the smae problem. If I dont feel like killing the starter I unplug the coolant temp sensor and force the glow plugs to fire. And cause the check engine light to come on. Any suggestions?
 

rmarkw

Veteran Member
Joined
Mar 16, 2004
Location
Central KY
TDI
Beetle, 2000, Blue
My top 4: 1.Injection timing 2.Weak starter 3.Weak battery
4. Air leak in fuel system, esp. O rings on the T-valve ontop of the fuel filter. Easy to check if you have the clear fuel line, my beetle doesn't.
Injection timing is an easy check also if you can find someone close with a vag-com. Advanced Auto Parts or Autozone will usually check battery and starter for free.
Many of us TDI owners, like myself have dealt with this frustrating problem. Good luck
 

rdkern

Top Post Dawg
Joined
May 21, 2004
Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
Since it starts well when really cold, I don't think it's the battery nor the timing. Perhaps the starter motor.

At 54, glow plugs should be out of the picture.

Starter motor - get it checked. That would be my #1 on the list.
 

cage

Top Post Dawg
Joined
Mar 25, 1999
Location
lakewood, ohio
Is this a new problem or your first winter with the car? A slight timing advance in adaptation goes a long way. I am 3 degrees advanced and the difference in starting and overall running is amazing. Also verify that the mechanical timing is at the upper 1/4 of the graph. One of the quirks of the TDI is that there is a grey area where it doesn't think it needs glow but it really does if you want a smooth start. On chilly days when it doesn't glow wait 5 sec. after the light goes out and cycle it again. It makes all the difference in the world.
 

Stan TDI

Veteran Member
Joined
Feb 10, 2003
Location
Eagan, Minnesota, USA
TDI
Jetta, 1997 1Z (RIP), 2002 Jetta GLS, 2002 Jetta GLS, 2006 Jetta Pkg 1
Might try *another* sensor. Wouldn't be the first time a new part was DOA.
This is good advice. I had very similar symptoms that were driving me crazy. I bought a new sensor (they are fairly cheap) and replaced it at the last TB/water pump change. You did replace the o-ring with the sensor right? When I installed the new one I also seated it a little deaper than the last install was. I had about 8 months of poor starting when about 35 - 65 degrees with the previous "new" collant temp sensor. If it was warmer, or colder than this, starting was fine. Very strange indeed. This may not have been necessary but my glow plug duration seemed short. It is improved after this. Also applied DeoxIt to the GP harness connections and all other electrical connections.

Also, the injection timing was slightly retarded and then it was advanced after the TB change. The injection timing is really important for the cold starts. Most have it set to the top 1/3 or 1/4 of the graph. This is advanced.
 

LindenKeith

Member
Joined
Dec 21, 2004
Location
Linden, Michigan
TDI
99 VW Beetle - 67 VW Beetle
Thanks for all the advice. I really appricate it!!! I am getting it Vag-Commed (lack of better word) Friday. Hopefully that will turn something up. I might try another sensor if it does not. Thanks again
 

GoFaster

Moderator at Large
Joined
Jun 16, 1999
Location
Brampton, Ontario, Canada
TDI
2006 Jetta TDI
Since it starts well when really cold, I don't think it's the battery nor the timing. Perhaps the starter motor.

At 54, glow plugs should be out of the picture.

Starter motor - get it checked. That would be my #1 on the list.
The circumstances that you describe are *precisely* why everyone is telling you to check the injection timing.

If the glow plugs are glowing red hot, fuel injected late into the cylinder is gonna fire no matter what. If the engine is warm, likewise, the fuel will fire even if it's injected a little late. If the engine is cold but not cold enough for the glow plugs to operate, that fuel which is getting injected late is coming in too late to fire.

Starter problem will normally cause hard hot starts, not hard cold starts (as long as it still *sorta* works ...)
 

rdkern

Top Post Dawg
Joined
May 21, 2004
Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
I hope we get a response as to what the problem turns out to be.

GoFaster - shouldn't the glow plugs be "on" between 25-40? If they are on, shouldn't it start as well as it does under 25?

Since it seems to be getting worse when the temp increases, I still think that the starter motor is a possibility. I understand that timing - expecially if it is being caused by a situation that is getting worse (stretching timing belt?) does cause hard starting. I just am having a problem with the difference between 30f and 20f - starting at 20 not at 30,) unless somthing that gets worse with temp is the problem. Since the problem seems to also be there at 60, I now doubt that its in the glow plug control system and suspect the starter motor. The motor does have a harder time turning at a proper speed if it's going out when it's warmer. Is the difference between 20 and 30 enough? Beats me.

Just giving my best guess and hope to learn something with my erroneous guesses.
 

John B.

Veteran Member
Joined
Feb 19, 2002
Location
Calgary
TDI
2002 Jetta GL TDI
Have you tried a new tank of fuel from a different supplier? I had a similar problem of difficult starting around those temperatures and it seemed to be the fuel. As soon as I put a new tank in, no problems.
 

MOGolf

Top Post Dawg
Joined
Jun 27, 2001
Location
underneath something
TDI
2001 Golf GLS TDI Reflex silver, rough road suspension and steel skid plate, 2004 Passat Variant, Candy White, rough road suspension and geared balanced shaft module, and much, much more. 2016 LR RR HSE TD6, 2019 Jaguar I-PACE
I suggested you meet Jetaah in my first response to this thread. Seriously!
 

JETaah

Vendor , w/Business number
Joined
Jan 18, 2001
Location
mi 48836
TDI
96 B4V, 1999.5 jettaIV,2005 BEW Beetle
Well, it for sure was retarded...right off scale.
The bolts in the pump sprocket looked torqued out.

But setting the pump pinned against TDC on the crank produced a 00-06 injection timing reading in the vagcom.
Pump shaft felt a little funny to me at one point; like it had end play. Couldn't get it to do it later. We advanced the injection pump timing to the upper part of the graph and we will see what happens.

Didn't check the cam timing...Sorry, Keith. I guess the cold went to my brain.


Don't know about the timing belt - it isn't that thick leathery backed one and its smoothe. Doesn't look frayed. Could it be the original?
85k on the odo wasn't it?

The tensioner was a tad loose but not too bad.
 

LindenKeith

Member
Joined
Dec 21, 2004
Location
Linden, Michigan
TDI
99 VW Beetle - 67 VW Beetle
well.... it was 23 degrees in my garage this morning. The glow plugs stayed on for only a moment and I was rather scared. It started right up. Thankyou so much for the help mr Jetaah. There is nothing worse then someone looking over your sholder as you work! You took it well.

It was freezing in you garage. I looked at the little thermometer you had in your garage and I think it was somewhere around 18 degrees. We were out there for about 2 hours and it took me four hours to warm my body back up! Thank again so much!!! and to all that helped with thier posts.
 

JETaah

Vendor , w/Business number
Joined
Jan 18, 2001
Location
mi 48836
TDI
96 B4V, 1999.5 jettaIV,2005 BEW Beetle
Glad to hear that it worked out.

Never saw a TB like the one you have. Most I have seen have some sort of texture on the back...unless it is just buffed out from many miles of service.

If I remember correctly you just got the car 3 months ago, yes?
If there is a doubt in your mind whether the belt is old or not you might consider just putting a new belt kit on and take the mistery out of it...peace of mind for the next 100K.
 
Top