Length of time the glow plugs burn

[dae06]

I've searched this and found many conflicting threads.

I would like to know how long the glow plugs stay on. (2005.5 Jetta TDI)

Some say they only come on below certain temperatures, some say they come on for every start (regardless of temperature), some say they only stay on as long as the glow plug light is on (dash light) and some say they stay on longer depending on the temperature.

It's been -21 F here lately in the mornings and the car had started pretty hard. If the GP's stay on longer depending on the temperature, how do I know if they have turned off or not? I want to keep them on as long as possible before turning the engine over, or possibly recycling the GP's a second time to create more heat. But if it is true that the GP's stay on only as long as the light stays on (~3 seconds) and I think they are on, lets say 20 seconds, I just lost all of the heat and am getting little to no benefit from the GP's.

 

[2004STARWARSTDI]

Glow plug time

On the PD TDI the glow plugs come on all the time at start and will continue for some time after called after glow to reduce emissions. They will shut off after engine is reved to about 2500 rpm , I believe. You will not see glow plug light on dash more than a few seconds but glow plugs will be on.

 

[dae06]

Great, it is much like my Power Stroke. The glow plug light comes on for only a few seconds but the glow plug actually stays on much longer (2 minutes?).

This was what I was hoping for.

 

[dae06]

Is there any way to know how long the GP is "burning"? I've read that there is a setting with a Vag-Com. What does this do? Does it set the maximum burn time, minimum burn time or something else.

What I really want to know is when it's -20 F, how long can I wait to get the maximum heat generated in the cylinder for the easiest start.

I have a 2005.5 MKV Jetta.

Thanks

 

[30_Yr_Dsl_Veteran]

They are on whenever dashboard light says they are on. They do not come on at all, above a certain temperature. In 16 years of our Jetta here in FLORIDA, glow plugs never, ever came on.

Once the temp. is cold enough for them to be on, the colder it is, the longer they stay on. It is not rocket science!

 

[meerschm]

I wait till the light goes out, then start. (have seen ten below, but not 20 below)

I guess you could say a "Hail Mary" after the light goes out for luck.

(on second thought that may be too long.)

if anyone had a hint, I would be willing to check with my VCDS. seems like it would be a neat trick, since you have to turn on the ignition for the VCDS to hook up and read the various values, but as soon as you turn on the ignition, the glow plugs start the cycle.

 

[meerschm]

http://www.natef.org/NATEF/media/NATEFMedia/VW%20Files/2-0-TDI-SSP.pdf

see page 77 (acrobat sheet 81 of 90)

 

[dae06]

If I'm reading correctly, below 64 degrees F, the glow plugs stay on for a maximum of 2 seconds?

 

[meerschm]

I read that as it takes a maximum of 2 seconds to get to temp.

I think the point to take away is that the best course is to wait for the glow plug lamp to go out, and then start the engine.

of course, this '08 document looks like it is for the CBEA, (my '09 for example) and not your earlier engine.

Sorry if it does not directly apply. saw it on another thread, and thought it good to share.

 

[dae06]

Thanks Meerschm,

Unfortunately I have not found a definitive answer on this.

Some say it stays on only as long as the GP indicator light on the dash, and some say it stays on longer depending on the temp.

I hope everone can see my delema, I don't want to wait to start for 30 seconds if the GP turned off after 3-4 seconds.

It's 9 degress F this morning so hooked up my voltmeter just to see if I could tell when they turn off with a voltage drop, no luck. when I turned the key, it showed 11.58 volts and after waiting 3 minutes there was no notable voltage recovery back towards the original 12.8 volts that the battery had before I turned on the key. (I did turn every accessory off that I could).

The next 2 days are supposed to have high temps around -10 to -15 F and lows down to -25 F. I hope it starts!!

 

[James & Son]

Here is the correct link for your year car which is a brm engine.
http://www.myarchive.us/richc/VW_TDI_with_PumpeDuse.pdf
see pg 53. You have ceramic glow plugs which are an improvement over the older ALH steel glow plugs. The reason for the pre-stage and second stage( lower current) is to limit the high current requirement prior to starting to reduce glow plug time to reach maximum temp.
Now the cr engine and later cars (2009 plus) have the latest and greatest with a cycling phase system that reduces current draw by 75% but because it uses higher voltage it is probably about 45% less current draw. It does not say if it allows operation during crank but it may for a cirtain period of time, before switching over to the lower current second stage.

Edit: I think Mike is right for the BRM in his post #5. Saying the Hail Mary and starting sounds good to me.

 

[meerschm]

From reading, it looks like the glow plug cycle preheat is done when the lamp stops, but a lower-intensity energy setting remains until you start moving.

I think the best plan for these engines is to follow the owners' manual steps. wait for the lamp to go off, and start her up. (say the hail mary while the lamp is on)

 

[30_Yr_Dsl_Veteran]

If I'm reading correctly, below 64 degrees F, the glow plugs stay on for a maximum of 2 seconds?

It is WAY lower than 64. Mine NEVER came on in 16 years, and temps. were in the 30's. And it started just fine too, without them.

 

[dae06]

Thanks guys, I'll give it a test tomorrow morning, they are say -24 F. I'll turn it over right after the glow plug indicator goes off.

It won't feel right, but i'll give it a try. I'm used to my 7.3 Ford F-350 where the GP's stay on for a couple of minutes.

 

[Vince Waldon]

Think of it this way: the glowplug LED is a "wait till I go out before starting" light.

The LED has *nothing* to do with whether your glow plugs are still running or not..and if you've found threads that say it does please post 'em up so we can go prevent some confusion. Also as you've read the glow plugs run for some time after the LED goes out... how long being dependent on coolant temperature.

The glow plug system is carefully monitored by the ECU...so if you have no Check Engine light there's a 99% chance your glow plugs are working *exactly* as they should.

If you want to extend the glow time before starting... easy peasy. Turn the key to "on", let the light run its cycle, and then quickly turn the key off and on again to run another heating cycle.

Lather, rinse, repeat as required... although if you need more than a couple cycles to get started, even on the coldest winter days, something else is going on.

 

[James & Son]

Thanks guys, I'll give it a test tomorrow morning, they are say -24 F. I'll turn it over right after the glow plug indicator goes off.

It won't feel right, but i'll give it a try. I'm used to my 7.3 Ford F-350 where the GP's stay on for a couple of minutes.

As vince said we do not know for sure what happens during the crank phase when the glow plug indicator start now goes out.

I decided the manufactures of the glow plugs should have that information. NSK had a self learn tutorial that requires a log in. So ended up with the manufacture Beru. Excellent explanation with graphs. There seem very little doubt VW is using the latest technology as it becomes available as describe by this manufacture although not NSK but an equal it would seem in the glow plug field.

See page 7 and make note of the graph. The glow is operated in three phases. Judge for yourself.
http://www.beru.com/download/produkte/TI04_en.pdf

 

[dae06]

Now I'm confused again.

Someone answer this question:

If you need to start your car in -25F temperature (no AC to plug in), how long would you wait after activating the glow plugs, before you tried to start the car?? (for maximum chamber pre-start heat)

I'll be interested in the different answers.

 

[Vince Waldon]

Only your ECU knows the answer to that question...and it will base its decision at the moment you turn the key to "on", by referring to the engine's coolant temperature.

Unless you install an actual monitoring LED on your glow plugs, there's no way to know how long the ECU's leaving the plugs on, at that specific temperature.

I'm a geek like that:


The ECU adjusts the length of time the "wait to start" LED stays on...automatically. If it's a warm summer day the LED will go off almost immediately. A kinda cold day... after 5 seconds. An Edmonton winter morning? 20 seconds or so.

Some people like to out-think the ECU and/or figure it's *really* cold out and so the glow plugs need more time (which may be why you think you're reading conflicting stories)... that's when they double or triple glow.

And, some people have engines with other issues (low compression, wrong oil, aging starter or battery)...and they double or triple glow.

It's really not that complicated... when the LED goes out, start the engine. If it doesn't start, try again.

 

[meerschm]

we also have three or four generations of TDI. all with different technology glow plugs and control systems.

I agree with Vince. trust the engineers who built the car. they do have snow and well-below zero temps in Germany.

Good luck with the cold weather. hope she starts right up for you.

 

[dae06]

This might be the problem. Whether its 60 degrees or -25 degrees, my LED goes out in about 2 seconds. Its never stayed on longer than that. Does everyone else have the GP light stay on different lengths of time?

 

[James & Son]

Now I'm confused again.

Someone answer this question:

If you need to start your car in -25F temperature (no AC to plug in), how long would you wait after activating the glow plugs, before you tried to start the car?? (for maximum chamber pre-start heat)

I'll be interested in the different answers.

With stock NSK glow plugs you will need 7 seconds before you start to crank at -25F. This is stated in the last link I provided. I repeat it will take 7 seconds to reach full stage 1 temperature at -25 F and then you will start the car. That is it I am out of here.

 

[dae06]

Unless you install an actual monitoring LED on your glow plugs, there's no way to know how long the ECU's leaving the plugs on, at that specific temperature.

I'm a geek like that:

Thanks again everyone.

7 seconds it is.

Vince, I did the same LED light with my 7.3 Ford diesel, but my relay is totally different than my Jetta. Is there anywhere that has instructions on how to connect the LED's to the Glow plug relay?

 

[meerschm]

With stock NSK glow plugs you will need 7 seconds before you start to crank at -25F. This is stated in the last link I provided. I repeat it will take 7 seconds to reach full stage 1 temperature at -25 F and then you will start the car. That is it I am out of here.

I guess I did not see that so clearly in the link to the Beru info. (not saying you are wrong, but I had a bit of trouble following your statement to the source.) do you think the info directly applies to our TDIs, and which model of glow plugs do you think are in which TDI engine? (if you are tired of discussing this, it is ok with me)

my '09 clearly goes through a longer glow plug pre-start cycle when it is cold (near zero f) does yours do the same? sounds like the '01 does too.

 

[thewalrusTDI]

minimum temp?

One thing that hasn't been addressed yet is a minimum temp to go through the glow plug startup?

If I live on the west coast and a 'cold' morning is 5 celsius (or 40-45ish F), is this a necessary step for me?

Thanks!

Ryan

 

[meerschm]

One thing that hasn't been addressed yet is a minimum temp to go through the glow plug startup?

If I live on the west coast and a 'cold' morning is 5 celsius (or 40-45ish F), is this a necessary step for me?

Thanks!

Ryan

you should follow the procedure in your owners manual. I always look at the glow plug lamp and wait for it to go out. does not take long in the summer, and when it does take longer, I have trained myself to wait for it, rather than crank twice.

 

[k1xv]

I have been told that the auto marketing department had a say as to when the glow plug light goes out. As told to me, the light goes out quickly because, if it did not, car owners would be dissatisfied by having to wait 30 seconds or more for the glow plugs to heat to their maximum. So, they go out after a few seconds, and usually, that is enough to get the engine going. However, the plugs continue to get voltage and continue to heat the chamber for about 30 seconds. Watching the volt meter on my Duramax truck seems to confirm this, at least for my 2003 Duramax.

 

[30_Yr_Dsl_Veteran]

One thing that hasn't been addressed yet is a minimum temp to go through the glow plug startup?

If I live on the west coast and a 'cold' morning is 5 celsius (or 40-45ish F), is this a necessary step for me?

Thanks!

Ryan

If your car starts just fine with what you've been doing, well that is the proof in the pudding.

 

[thewalrusTDI]

you should follow the procedure in your owners manual. I always look at the glow plug lamp and wait for it to go out. does not take long in the summer, and when it does take longer, I have trained myself to wait for it, rather than crank twice.

Thanks Mike, will do!

 

[dae06]

Bad news,

I left my car outside from 7:00 am to 2:00 pm today at -12F, I did the 7 second wait for the gp burn (dash light stayed on for 2-3 seconds as usual), turned it over and almost nothing, it turned over very slow. I decided to hook up the voltmeter and when I turned it over, it dropped to 5 volts. Not enough to start a TDI in these temperatures.

I have a 2 year 10 month old Everstart Maxx H6 (#13) battery. I'm a little disappointed in the battery right now.

I'm still not sure on how the GP's are working either. I can't trust the car in these temps which really sucks.

 

[meerschm]

I feel your pain