PDA

View Full Version : Metronome glow plugs


GEARS
01-25-2013, 02:21 AM
I have a quick question.


When I go to start my Sprinter in the morning, once I turn the key to the on position the glow plugs cycle on & off every couple seconds like a metronome. If the weather isn't too cold, let's say above 35*F, it'll start just fine.

However it won't fire right up if the temps are between 30*F to 20*F. I will put up a fuss and eventually come to life with a sooty black cloud. Again the metronome cycling of the glow plugs.

But if the temps are below 20*F outside the glow plugs module will clamp on good and solid and I can fire it up with merely a bump of the key. If they are cycling on & off, I'll have to make several attempts at getting it to start.


What is causing the cycling of the glow plugs?

I know they are meant to cycle after the engine has fired up but it doesn't seem right for it to cycle tick-tock-tick-tock when the engine hasn't even started.


Thanks in advance. :cheers:

GEARS
01-25-2013, 02:39 AM
Also the glow plugs have been changed and the resistance is the same on all 5 and I have the improved glow plug module.

Aqua Puttana
01-25-2013, 01:17 PM
I have a quick question.
Wish that I had a quick answer. :thinking:

When I go to start my Sprinter in the morning, once I turn the key to the on position the glow plugs cycle on & off every couple seconds like a metronome. If the weather isn't too cold, let's say above 35*F, it'll start just fine.

However it won't fire right up if the temps are between 30*F to 20*F. I will put up a fuss and eventually come to life with a sooty black cloud. Again the metronome cycling of the glow plugs.

But if the temps are below 20*F outside the glow plugs module will clamp on good and solid and I can fire it up with merely a bump of the key. If they are cycling on & off, I'll have to make several attempts at getting it to start.


What is causing the cycling of the glow plugs?

I know they are meant to cycle after the engine has fired up but it doesn't seem right for it to cycle tick-tock-tick-tock when the engine hasn't even started.


Thanks in advance. :cheers:
Your problems seem to be around the cusp of the 32F temperature range where the ECM would call on the glow plugs to operate. Once you're dwn to the lower temperatures you are more solidly in the range where the ECM would want them.

Note below:

If no data transfer takes place with the ECM, preglowing is switched off after two seconds.

__

49858

49859

49860


I remembered that you had some other threads about glow plug problems. A search dug up these.



In this thread you mentioned an IAT code. I don't know what temperature sensor the ECM uses to decide that it is cold enough that you need glow plugs. I always ASS-U-ME'd that it would be the engine tmeperature or ambient temperature sensor. Maybe it uses the IAT sensor? Did you ever change the IAT or did the code just go away?

http://sprinter-source.com/forum/showthread.php?t=6518&highlight=glow+plug

Your glow plug "ticking" has been going on for a time now?

http://sprinter-source.com/forum/showthread.php?t=14576&highlight=glow+plug

http://sprinter-source.com/forum/showthread.php?t=14576&highlight=glow+plug

http://sprinter-source.com/forum/showthread.php?t=13990&highlight=glow+plug

I think that the IAT is fairly inexpensive. It may be worth swapping out if that hasn't been done yet. A wonky signal connection from the ECM to the Glow Plug Module might also cause a two second metronome type reaction.

Sorry I can't offer more. vic