How To extend glow time with Vag-com - ALH

Wingnut

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First and foremost....Big thanks to member Fred (samfisher) who did the experimenting to find this info out. This mod will help a lot of folks with cold start problems who cannot rectify them with a timing adjustment.

Now as we all now, some cars have a difficult time starting when it is just above the freezing mark. This is due to the fact the glow plugs do not come on if the temps are above 9*C or 48*F (or somewhere around there). Any warmer and the ambient temp is usually ok to start fine and any colder than that and the plugs will glow to asist with starting. Of course there is a margin of error a few degrees either way. Also, atmoshperic pressure will affect your glow time too. The higher the pressure, the shorter the glow time. Thats why people at higher elevations will have a longer glow time, even above 9*C.

So in order to extend the glow time, you simply have to log into the engine module and make an adaptation change in group 12.

Here are the directions:

1) Turn on ignition
2) Go to engine controler
3) Log in using 12233 as the code
4) Click on Adaptation and go to group 12.
5) Change adaptation number from 32768 (default) to somewhere around 32700
6) Click test, then save the new value.
7) Close controler
8) Turn off ignition and turn back on again.
9) Go to the engine controler & log in again.
10) Go to adaptation block 12 and you should see a change in the second window. This value is the amount of time in seconds that the glow plugs will be active.

Note, you must do this with a cold engine to be able to see the results of your adaptation. You can do the adaptation at any time, but won't notice anything till the engine temp is cold. Also, the new glow time will not appear in the second window (no units) after you do the adaptaion. You must turn the ignition off & on and re-log in to the engine controler to see the results of the adaptation.

I did some experimenting at different temps and this is what I found:

Engine coolant temp was at 7.2*C
Normal glow time is 1.01 seconds



I then changed the adaptation value to 32700 (same ECT)
Glow duration is now 2.88 seconds


And finally, I changed the adaptation to 32650
Glow time was 6.61 seconds:


Now, in my opinion, this last adaptation seting is too much. We only need a few seconds of glow as these plugs get hot very quickly. If you adapt it to this setting, you may prematurely burn out your plugs? Now having said that, everyones car is different and you may have more or less glow time than me at that setting & temp. You will have to adjust it according to your own cars needs. I would recommend setting it to 32700 first and see if your car starts ok and then leave it. If not, and you need a litle more glow time, adjust accordingly. I also have to mention, that this adaptation was done on an ALH engine. I have not tried it on a 1Z(pre 99.5) or BEW PD engine. Hopefully others will experiment and post their results.

For reference, here are some screen shots I took at 13.5*C

Stock setting - no glow


And with an adaptation setting of 32650
glow time is 2.57 seconds


So basically, what you need to do, is find out at what temperature your car has a hard time starting and adjust the glow time according to that temperature. Around 3 seconds is all you need, so if you have a hard time starting the car at 13.5*C (56*F), then set the adaptation to around 32650. If you car starts fine at that temp, but has a hard time around 7*C (45*F), then set the adaptation value to around 32700. Again, this is only my own car and yours may differ slightly. I am also very close to sea level, so if you are higher than sea level, your values may differ also...this is just a guideline.

I hope this helps out all of you who have cold starting issues. But also be aware that glow time is not the only thing to affect cold starts. Do not do this mod to mask another underlying problem. Poor injection timing (mechanical) will also affect cold starts and you should check & adjust that as well before trying this adjustment.

Good luck to all and thanks again to samfisher for the legwork on finding this info out.

Disclaimer: Even though i did this to my car, you are doing it to your car at your own risk. If you blow glow plugs at a high rate, you are your own warranty. This is for informational purposes only :)
 
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BrianM

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2001 GLS 5-speed, Loaded
LOL!!! I wanted to see what effect altitude had... (I don't have the ability to take screenshots on my VAGcom laptop right now ~ fixed)

Standard setting, 65*C, 5.36 seconds of GP time. I upped the adaptation # to 32800 and it dropped to 5.31 seconds.

Since my car has done 4~6 8+ second GP burns every day for 8 months, I doubt that a 6~7 sec burn will have any issue for most people. I'm going to fuss with this though and see how short of a GP burn I can get away with at altitude. Thanks to Wingnut AND SamFischer for the information.

Edited to add an image ~ I got Paint loaded back onto my laptop without having to reboot. :D

 
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compu_85

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COOL!!! Now I don't need to double plug anymore!!! THANKS!!!

I'm doing this right now!!!

EDIT Done! Engine was too hot to see anything right now, can check tomorow. Oh, and Wingnut, your engine comptuer certinally has an interesting part description :D

-J
 
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JETaah

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Take a bow guys!!!!
this is terrific news in Michigan.
 

dieseldorf

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I'm luvin' it! Excellent job once again, Wingnut, for another
Wingnut exclusiv !!!!!!!!!!!
 
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Wingnut

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Silver 2003 Jetta Wagon
BrianM said:
LOL!!! I wanted to see what effect altitude had... (I don't have the ability to take screenshots on my VAGcom laptop right now ~ fixed)

Standard setting, 65*C, 5.36 seconds of GP time. I upped the adaptation # to 32800 and it dropped to 5.31 seconds.

Since my car has done 4~6 8+ second GP burns every day for 8 months, I doubt that a 6~7 sec burn will have any issue for most people. I'm going to fuss with this though and see how short of a GP burn I can get away with at altitude. Thanks to Wingnut AND SamFischer for the information.

Edited to add an image ~ I got Paint loaded back onto my laptop without having to reboot. :D
Wow, thats a long glow time at such a high temp. Good to know the plugs will be ok at that duration. I knew altitude extended the glow time, but I had no idea it was that dramatic. Thanks for the info.
 

compu_85

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Remember the plugs run continuously below 2400 rmp (or whatever the cutoff it, it's right around there) until the engine starts to warm up. That is usually a couple of minutes on my car, so a few extra seconds of preglow shouldn't hurt anything IMHO.

-J
 
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DPM

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2019 Rav4 AWD Hybrid, Citroen C4 BlueHDI
Damn, you got there before me...

Yup, if you look at any of the tech info on these modern Bosch g/ps, you'll find that they have two elements, the one at the tip as a heater, plus a longer coil farther along the body which acts as a current limiter. This and clever selection of element wire alloy results in a fast heatup and a low-enough steady state temperature that they can be energised damn-near endlessly.
 

P-car

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Thanks for the info. I have been wanting to extend my glow time for a while now. I had a 4 sec glow at 0degs. Now I have a 9 sec. glow at 0degs.

Thanks again
Dean
 

dieseldorf

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ex- 1996 wagon, ex-2000 Jetta
This will be a distinct benefit to those with hi mileage GPs....Remember: they get much weaker before they fail.

Bumping up the cold glow period should be a real benefit to those in cold climates!


Junk:




New:

 

mtltdi

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damn! That looks like a little lightsaber. hehe

Great info, to be saved to my harddrive immediately.
 

Variant TDI

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I'm curious... Do the glowplugs shut off after the glowplug light goes out? Or is the Glow plug light just an idiot timer to ask you not to start the car until the light turns off?

I guess my question is... Can't you just wait a few extra seconds to start the car?

The plugs are supposed to be on durring periods when the engine running, but still cold. Do they shut off, just to turn back on again?
 

jck66

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Variant TDI said:
I'm curious... Do the glowplugs shut off after the glowplug light goes out? Or is the Glow plug light just an idiot timer to ask you not to start the car until the light turns off?

I guess my question is... Can't you just wait a few extra seconds to start the car?

The plugs are supposed to be on durring periods when the engine running, but still cold. Do they shut off, just to turn back on again?
I believe the idiot light (after the "power on self-test") is linked to the actual GP operation. You can definitely see a difference in the idiot light time depending on ambient temperature.

No, if the car thinks it's warm enough not to need any GP, you'll just get the POST (lamp test) and no GP action. Not like the old days, when the GP cycled every time you cycled the key.

Yes. :)
 

Wingnut

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The idiot light is an indicator of when the glow plugs are active pre startup. When the light goes out, so does the power to the plugs. After the engine is started, however, you get afterglow while the RPM is below 2500. During this afterglow, the glow plug light does not come on, but the glow plugs are on. You can hear all this by listening for the click of the relay. If its cold enough, you can hear the relay click on and off as you go over or under 2500 RPM.
 

Schneeflocke

New member
Joined
Nov 30, 2005
hi @wingnut

I would like to extend the glow time by my car (A6 2,5 TDI AFB).
The difference to your how to is: i do not need to login to adapt values higher than 32768.

But values over 32768 reduce glow time. So I need also to reduce the value. But this is impossible. I can tipp in a value lower that but i can't test or save that.

What do you think about this?


Schneeflocke
 

n1das

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2014 BMW 535xd ///M-Sport, 2012 BMW X5 Xdrive35d, former 3x TDI owner
Afterglow

Variant TDI said:
I'm curious... Do the glowplugs shut off after the glowplug light goes out? Or is the Glow plug light just an idiot timer to ask you not to start the car until the light turns off?

I guess my question is... Can't you just wait a few extra seconds to start the car?

The plugs are supposed to be on durring periods when the engine running, but still cold. Do they shut off, just to turn back on again?
Yes, you can wait a few extra seconds to start the car after the GP light goes off. This is assuming the GPs turned ON at all before a cold start. You might need to do the adaptation to get some glow time at warmer temps if needed. If it's warm enough that the GPs didn't turn ON at all, then waiting longer before starting won't help.

When it's cold enough for GPs to turn ON before a cold start, you can get additional glow time by waiting several seconds after the GP light goes out. One trick I like to do in the dead of winter is to leave the car door open during the glow period. I can see the interior lights dim slightly during the glow period and stay dim for several seconds after the GP light goes out. I see the lights brighten back up when the GPs finally do turn off. I watch for the GPs to finally turn off and then I crank the engine IMMEDIATELY as soon as they turn off. Easy cold start! No need to double-glow! Less load on the battery too. I've also found that during the extended glow period, I can see the interior lights brighten up slightly right before they turn off. They draw less current as they get up to temp...another visual indication that they're hot.

One mod I've thought about doing is to install a light connected to the GP circuit. I'll have a good visual indication of when the GPs are ACTUALLY ON. I'll also see how much they actually stay ON following a cold start and while under 2500RPM. I'd rather use that indicator than the normal GP idiot light controlled by the ECU.

I don't know about 'afterglow' following a cold start and under 2500RPMs on the ALH (non-PD) engines. Supposedly they 'afterglow' for about 10 seconds and while under 2500RPM when cold. They may stay on longer while cold and under 2500RPM. I guess if you're going to rev it above 2500RPM immediately after a cold start, it won't need any help from the GPs.

From what I read about the PD engines (BEW engine code), the GPs always afterglow for about 10 seconds following a cold start, whether or not it was preceeded by a preglow period before the cold start. I don't know if they stay on any longer while cold and under 2500RPM.

In terms of GP life, I don't think a few extra seconds of preglow time will adversely affect GP life. They're designed to handle long periods of 'afterglow'. I'm also willing to sacrifice a little bit of GP life to have easy cold starts in the dead of winter. Glowplugs are easy enough to change.

I'll try the VAG-COM adapation on my Golf (ALH engine) and see what happens. I've wanted to extend the glow time since my Golf TDI was new. If I can adapt the glow time via VAG-COM, I won't need to do the GP light mod I was thinking about.

I'll also check this out on my 05 PD Jetta Wagen (BEW engine). I've found on the PD Wagen that the glow time is always slightly longer than in my Golf...also at temps where I get no glow at all in the Golf (ALH engine). I may not need to tweak anything on the PD Jetta Wagen. I'll learn how the PD Jetta Wagen behaves as we get more into the winter cold temps.
 

n1das

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GP light mod idea

n1das said:
One mod I've thought about doing is to install a light connected to the GP circuit. I'll have a good visual indication of when the GPs are ACTUALLY ON. I'll also see how much they actually stay ON following a cold start and while under 2500RPM. I'd rather use that indicator than the normal GP idiot light controlled by the ECU.
After thinking about it, I'm going to look into doing this mod anyway, whether or not I adjust the preglow time via VAG-COM. It would be good to have a reliable visual indication of when the GPs are ACTUALLY ON.:cool:
 

dieseldorf

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stick a voltmeter in the cigarette lighter....you'll see when the GPs are ON/OFF. ;)
 

dieseldorf

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ex- 1996 wagon, ex-2000 Jetta
Schneeflocke said:
But values over 32768 reduce glow time. So I need also to reduce the value. But this is impossible. I can tipp in a value lower that but i can't test or save that.


try using the up and down arrows....I had the same issue when I reset mine. it took a few tries before it would take.
 

n1das

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dieseldorf said:
stick a voltmeter in the cigarette lighter....you'll see when the GPs are ON/OFF. ;)
That works too! However I don't always have one handy when hopping in the (cold) car to go somewhere.

Some people like to listen for the click sound from the GP relay to know when the GPs switch on/off. I've never been able to hear mine. Watching for the slight dim of the interior lights works.

A light on the dash connected directly to the GP circuit would be a worthwhile addition. I'll know for real whether the GPs are ON/OFF.

I'll try adapting the preglow time on my Golf and see what happens.

Also thanks to Wingnut for posting this mod! I've been wanting a mod like this since my Golf TDI was new. Although I've never had any winter cold start issues, I've wanted to extend the preglow time to help make winter cold starts as easy as possible.
 
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n1das

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I tried the adaptation today on my 02 Golf (ALH engine).
The adaptation works as advertised.

I also tried this on my 05 PD Jetta Wagen. It appears that it DOES NOT WORK on the BEW PD engine. Measuring block #12 shows the same information as on the ALH (non-PD) engine. The adaptation channel appears to be 08 instead of 12. Adaptation values accepted by the ECU are in the range of 0-100. It had no effect on preglow time. It might affect the afterglow time. After playing around with adaptation values, I ended up leaving it at the factory default of 0.

This mod works as advertised on ALH (non-PD) engines.
It appears that it DOES NOT WORK on the BEW PD engine.
Anybody tried it on a 1Z engine yet?
 
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JetPuf

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I'm reading here that the GP's turn on and off as you go above and below the 2500 rpm mark, it has been my understanding that they are on the post glow until you go over the 2500 prm mark and do not come back on after that and that is one reason people recomend keeping rpm's low when the engine is cold. I could be incorrect, but I do recall having seen this in vag-com outputs as well -- Commments?
 

jsrmonster

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Hi,

I have been experimenting with gp operation on my hot bench for 2 years with the AFN/AHF/ASV110 euro cars.

The 02-03 immo3 tdi's actually cycle the gp's every start for emissions even when hot (gp dash-light off however). The glow time varies between cold warm and hot starts. Interesting thing is that when cold, the gp's will actually glow longer than the lite indicates on the dash. I often give demo's on my hot bench of the gp cycle using a simple test light on the solid state relay. The test light stays lit 2 seconds after the dash squiggle goes out!

The 99.5-01 immo2 cars actually light the plugs exactly the same as the dash gp light indicates. The ecu drops a ground at pin42 to pull up the gp relay, however the immo3 cars feed 5vdc high on pin 42 to enable the solid state gp (smart) relay. The immo3 cars have smarter relays that satisfy stricter emissions requirments for individual plug diagnosis.

I don't think the max gp cycle is bad, when I was at Kerma's I noticed his light always glows a long cycle at 4500 ft. I keep mine at max glow period and it still wakes up great (cold) with 12mm and race injectors.

If I had a nickle for every email and phone call regarding gp faults I'd be a rich man. Best way to diagnose gp operation is to remove them and put them back in the harness and ground the base w/jumper, unplug the coolant temp sensor and hit the key on (don't start) and watch them glow. The tips should have white spots on them if working properly. If they are heavy soot covered (fuzzy) they are probably bad. Checking resistance is also a way to check them, but sometimes bad ones will indicate resistance, but wont' actually glow.

btw, awesome post wingnut, you rule! :cool:

Jeff
 

compu_85

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Jeff,

I've noticed in my 99.5 that the glow plugs shut off ~2 secconds after the light on the dash goes out (on cold days). I can hear the realy click off, and the interior lights get brighter too.

-J
 

n1das

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Can't hear GP relay click

jsrmonster said:
...however the immo3 cars feed 5vdc high on pin 42 to enable the solid state gp (smart) relay. The immo3 cars have smarter relays that satisfy stricter emissions requirments for individual plug diagnosis.
That explains why I've never heard the GP relay click in my 02 Golf TDI (ALH engine).

Solid State Relay --> No relay contacts to wear out and fail. :cool:
 

Brock_from_WI

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Any idea if this affects the coolant heater plugs in the manuals as well?

I dropped mine down to 32700, I will find out tonight how this works when I leave work, it's 10F outside right now and been sitting for over 8 hours already.
 

n1das

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Does the adaptation affect threshold for preglow?

One question I've been asked is does the adaptation affect the temperature threshold at which you'll start to get some pre-glow time? We know the adaptation changes the pre-glow time, assuming the engine is cold enough to get any pre-glow at all, but does it also affect the temperature threshold for preglow?

With an ALH engine with the stock setting, the threshold to get any pre-glow at all is somewhere around 48F (9C) at sea level atmospheric pressure. Warmer than that, we get virtually no preglow at all. Below the threshold temp, we start to get preglow time. If we lengthen the preglow time via adaptation, does this also raise the temperature threshold where we start to get preglow, say to around 55-60F instead of 48F? This could potentially help B100 users.

My gut feeling is the ECU has a preglow time vs. temp map and the adaptation value simply shifts the entire map up or down. Shift the entire map upwards to get a longer preglow time at a given temp and you also raise the threshold temp for preglow to occur. The intercept point for zero preglow now occurs at a higher temp because the entire graph has been shifted upward. Experts, please chime in and correct me if I'm wrong. This is just a theory. Jeff (jsrmonster), do you have any info on this?

Some experimentation at slightly warmer temps would be worthwhile.:cool:
 
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