02 ALH Jetta stumbly at start when cold... normal?

speedfreeq

Member
Joined
Sep 14, 2011
Location
Weaverville, NC
TDI
02 Jetta ALH/01M, 123k
The past few mornings have been low 20's (F) out, and I've noticed that the glow plug cycle still seems short- maybe 2 seconds max? The car starts right up, but stumbles on idle for a few seconds before it cleans up.
Is this normal? It's our first winter with a TDI, but not with diesels... I'm used to a 20 second GP cycle on my Powerstroke, and block heaters, etc...
Any good intel on care & feeding of the ALH during the cold months would be welcomed.

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Corsair

Veteran Member
Joined
Aug 17, 2003
Location
Weedsport, New York
TDI
2002 Jetta GLS TDI 5M
yes, a few seconds of stumble and a little smoke is, imho, typical. (at least, mine has always....)
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The engine should catch promptly and progressively smooth out as the seconds tick away. It should not sit there and cough like it's having trouble for extended time. Extended cranking or extended coughing could mean retarded timing- worth checking as mentioned above.
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Frankly, mine starts worse at 35-40F than it does at 25F. That could be glow plug related, as I think the glow plugs are more active around 20F than 40F.
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You don't "need" this, but if you are inclined to make the extra expenditure and effort to connect / disconnect an extension cord and timer, it will make the winter process much improved; There are aftermarket coolant heaters available that plug into 110 wall outlet. There are multiple manufacturers, but I highly recommend one in particular: google frostheater (frost heater ?) They make kits specifically designed for the TDI, with bracket and pre-bent coolant hose for the TDI. Cost is reasonable, installation is not too difficult. Again, in NC you don't "need" an extra heater- you can expect your car to start reliably. But if you're willing to get the frostheater and plug the car in at night and unplug in the morning etc., the reward will be some degree of cabin heat available immediately at startup. That makes brownie points with GF / spouse...
 
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azianjiu

Well-known member
Joined
Jul 14, 2009
Location
Centreville, VA
TDI
2000 Jetta
I absolutely agree with the statement that the car is harder to start at 35-40F. I think the glow plugs don't activate until a certain temperature and it hasn't his that threshold at 35-40F. I find my car starting promptly after the glow plugs go off at 25F but I crank for 5 sec or so at 35-40F till it catches.
 
Joined
Oct 4, 2010
Location
Columbus, OH
TDI
2003
Its about mid 30's here in Ohio. I have been finding it difficult for mine to start as well. The glow plugs goes on for a very short period <2 seconds if that, and normally I need to give it a few tries before it will actually starts. I am going to try to unplug the coolant sensor to see if that helps. If it does, I will try to change the glow duration. What I want to know: is there a way to change the glow plug temp. activation point? I read that at 9 degrees C is when it kicks in, any way to make that say 15c?
 

Corsair

Veteran Member
Joined
Aug 17, 2003
Location
Weedsport, New York
TDI
2002 Jetta GLS TDI 5M
fwiw- mine has never cranked on the starter for more than about 1 second before firing, regardless of temperature. Typical start sequence is the engine fires on, I would say, the first or second revolution of the crank. I set my timing just below the upper limit. Maybe I'm lucky and I got one of the more cooperative ones.
 

azianjiu

Well-known member
Joined
Jul 14, 2009
Location
Centreville, VA
TDI
2000 Jetta
Hmm perhaps I need a new battery. I bought my car used and never thought twice about the battery. I looked under the case and it says the battery has ~600 CCA. I think the OEM is supposed to have in the 800s or something.
 

Tintman718

Veteran Member
Joined
Oct 7, 2011
Location
nyc
TDI
99.5 Golf (5-spd), '10 Golf (6-spd), '12 Touareg
I find myself cranking for about 5 seconds these cold mornings (35-45F). It sputters and doesn't always start on the first try. After it starts, it shoots a huge plume of smoke, but clears up within a few seconds. I'm guessing the smoke is from the fuel accumulating on the cylinder walls during cranking. Timing is in the middle of the graph. Any input?
 
Joined
Oct 4, 2010
Location
Columbus, OH
TDI
2003
Tint,

That is exactly what my car does. I would assume you are correct about the cause of the smoke. I also have my timing on the middle of the graph. I am going to increase my glow plug timing as well as advance injection timing and see if that makes a difference. I let you know the results.
 

Powder Hound

Top Post Dawg
Joined
Oct 25, 1999
Location
Under a Bridge, Crestview, FL, USA
TDI
'00 Golf 4dr White 5sp, '02 Jettachero 5sp, Wife's '03 NB Platinum Gray auto(!)
Anytime I've noticed starting problems that weren't battery discharge related, it was timing or compression.

The compression problem I had was on my 2-dr. When cold, it would stumble and smoke on startup, then when warm it would run great. After resetting the timing, it was still problematic. Then I replaced the glow plugs (the harness was shot, so while I was in there...) I found 2 of them with carbon packed threads. New plugs correctly torqued and seated instantly produced easier starts, no smoke, no stumbling.
 

n1das

TDIClub Enthusiast, Veteran Member
Joined
Jun 11, 2002
Location
Nashua, NH, USA
TDI
2014 BMW 535xd ///M-Sport, 2012 BMW X5 Xdrive35d, former 3x TDI owner
I absolutely agree with the statement that the car is harder to start at 35-40F. I think the glow plugs don't activate until a certain temperature and it hasn't his that threshold at 35-40F. I find my car starting promptly after the glow plugs go off at 25F but I crank for 5 sec or so at 35-40F till it catches.
Sounds like retarded injection timing. Your TDI has all the classic symptoms. When was the timing belt last changed and who did the work? If it was done by a VW dealer, it's almost guaranteed to be screwed up due to the "mark and pray" method used (totally wrong) and resulting in severely retarded injection timing and also retarded cam/crank timing. :eek: Timing will also retard very slightly due to normal stretch of the timing belt as it ages. The ideal place for injection timing to be is up at the advanced edge of the timing spec on the graph but still within spec. This is best for power and MPGs, low smoke, and easy cold starts.

With injection timing and cam/crank timing properly set and assuming the GP system is functioning, it should fire right up. If you have to crank it more than about 2 seconds, something is wrong. A properly running ALH is normally able to fire as early as the first or second compression stroke when cranking. Usually it takes less than a second of cranking and its running. Normally it's Crank-crank-Vroommmm.
 
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n1das

TDIClub Enthusiast, Veteran Member
Joined
Jun 11, 2002
Location
Nashua, NH, USA
TDI
2014 BMW 535xd ///M-Sport, 2012 BMW X5 Xdrive35d, former 3x TDI owner
You can cycle the key 2-3 times to give it some more glow...

I would check the timing with vag-com, make sure you are near the top of the graph.
2002+ TDIs have a solid state GP relay and the GPs stay on for several seconds (~ 10 seconds) after the idot GP light on the dash goes out. No need to cycle the key more than once.

One trick I've done in my 02 Golf (sold it last year) in subzero temps is watch for the interior lights to dim slightly to indicate the GPs are in use. I watch for the interior lights to brighten back up again, several seconds after the GP light on the dash went out, indicating the GPs just turned off. I hit the starter the instant I see the interior lights brighten up. It cranks easier this way too because of less load on the battery due to the GPs having just turned OFF. The GPs will stay hot enough for a few seconds after they turn off. It fires right up on the first try in the bitter cold using this trick.

Good luck.
 

azianjiu

Well-known member
Joined
Jul 14, 2009
Location
Centreville, VA
TDI
2000 Jetta
Sounds like retarded injection timing. Your TDI has all the classic symptoms. When was the timing belt last changed and who did the work? If it was done by a VW dealer, it's almost guaranteed to be screwed up due to the "mark and pray" method used (totally wrong) and resulting in severely retarded injection timing and also retarded cam/crank timing. :eek: Timing will also retard very slightly due to normal stretch of the timing belt as it ages. The ideal place for injection timing to be is up at the advanced edge of the timing spec on the graph but still within spec. This is best for power and MPGs, low smoke, and easy cold starts.

With injection timing and cam/crank timing properly set and assuming the GP system is functioning, it should fire right up. If you have to crank it more than about 2 seconds, something is wrong. A properly running ALH is normally able to fire as early as the first or second compression stroke when cranking. Usually it takes less than a second of cranking and its running. Normally it's Crank-crank-Vroommmm.
Hmm I will have it rechecked. I had it changed 40k miles ago by a guru. Its weird that when its cold enough for the glow plugs to fire the car will start no problem. Could this also be a battery issue?
 
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