320cdi om642 bad cold start

[Vlafutz4life]

Hello my friend
Did you finnaly solved the heavy cold start?
New spark glow relay?
Thanks

 

[Martoname]

здрасти Не е разкрито, но от други теми, където същият проблем, това е лошото реле за подгревни свещи (също, без GP светлина след стартиране). В Литва тази зима беше много студена. -22~ мравка, когато е студено, GP светва за 2-3 секунди и колата пали перфектно през цялата зима. Но сега, когато температурата е +15, сутрин gp светлината идва за няколко милисекунди и ако опитам да стартирам и не чакам допълнителни секунди, те правят някои допълнителни манивела. Мисля да сменя релето по-късно в бъдеще, може би есента. Защото ако помислите логично, тези допълнителни секунди след изгасването на GP светлината може да са свързани само с отопление. 1 път тествах така. Опитайте да изчакате още 7-10 секунди, след като лампата на GP изгасне, след това изключете запалването, след това отново запалете и не чакайте, и стартира перфектно. Ако смените релето, публикувайте тук

дid you decide the problem with poor cold start? I have the same problem on my Ml 280cdi- glow plugs are new, glow plugs reley is new too, but if I start immediately after glow plugs lamps off it’s difficult. If wait 4-5 seconds start normal

 

[Doug1234]

The glow plugs are still on after the light goes out , these modern engines will even use them on a nearly fully warm engine for emissions reasons … so let the light go out and just count to five and then start.
The om642 also will not start until engine rpm reaches 200rpm , ecu will not fire injectors until that rpm.
Old school engines with 12 volt glow plugs the relay switched them off when light went out, later versions had post glow which kept them on for a while after start up … modern glow plugs are 4.5 volts and on a lot longer and if you were driving and the outside air was below freezing I would not be surprised if they were in use

 

[Martoname]

The glow plugs are still on after the light goes out , these modern engines will even use them on a nearly fully warm engine for emissions reasons … so let the light go out and just count to five and then start.
The om642 also will not start until engine rpm reaches 200rpm , ecu will not fire injectors until that rpm.
Old school engines with 12 volt glow plugs the relay switched them off when light went out, later versions had post glow which kept them on for a while after start up … modern glow plugs are 4.5 volts and on a lot longer and if you were driving and the outside air was below freezing I would not be surprised if they were in use

RPM are ok, battery is new- agm, no mistakes in ecu, but I don’t like to wait 5 seconds after lamp is off

 

[mersum1es]

Then you have to buy car with gasoline engine... diesels are like that

 

[supernoodle]

Hmm, I'm with @Martoname on this one. The whole point of the glow lamp is to tell the driver when it's ok to crank. It even says so in the owners manual...

 

[onefortheroad]

дid you decide the problem with poor cold start? I have the same problem on my Ml 280cdi- glow plugs are new, glow plugs reley is new too, but if I start immediately after glow plugs lamps off it’s difficult. If wait 4-5 seconds start normal

What happens if you do two glow plug ignition cycles ? Does it then start instantly???

 

[Martoname]

What happens if you do two glow plug ignition cycles ? Does it then start instantly???

My ml need only 3-4 seconds after lamp of and start immediately, no need to second ignition plug. When the oustside temperature is 10 degrees and more the car starts when glow plugs lamp is off immediately

 

[onefortheroad]

My ml need only 3-4 seconds after lamp of and start immediately, no need to second ignition plug. When the oustside temperature is 10 degrees and more the car starts when glow plugs lamp is off immediately

So what is your problem then ??

 

[Martoname]

onefortheroad, Hello!​

Problem is, when it's cold, I have to wait a certain number of seconds after the heater light goes out and then start. This is annoying to me as I have friends with the same Mercedes and their car starts as soon as the glow plug light goes out. For that I think there is a problem somewhere.​

 

[onefortheroad]

onefortheroad, Hello!​

Problem is, when it's cold, I have to wait a certain number of seconds after the heater light goes out and then start. This is annoying to me as I have friends with the same Mercedes and their car starts as soon as the glow plug light goes out. For that I think there is a problem somewhere.​

So glad of the bold font , I didn't have my reading glasses with me.

 

[mersum1es]

ok, in that case it could be primer pressure problem.

 

[onefortheroad]

ok, in that case it could be primer pressure problem.

This is what I was getting at but poster assumes it's glow plug related .

 

[Martoname]

Thanks onefortheroad, Mersum 1 es, but I can’t understand wats mean “but poster assumes”? The glow plugs are new- beru, glow plugs reley is too new / sorry for my English/

 

[mersum1es]

Ok... so basics; your fuel system is not getting enough fuel pressure at start, because primer pump is not able to deliver enough flow to hp pump. This leads to situation where you need to crank longer time, to get enough pressure to rail, because ECU does not allow injection until certain pressure levele is reached. If you try to do two ingntion cycles - ignition to 1 - wait glow plug light shut down - igntition to zero - ingnition to 1 - wait glow plug indicator shut down and immediately then put ignition to start - should start right away.

You have probably inner leak somewhere, I would bet injectors. Then it could be clogged fuel filter, clogged primer pump but these would cause problems in driving too.

 

[Martoname]

Ok... so basics; your fuel system is not getting enough fuel pressure at start, because primer pump is not able to deliver enough flow to hp pump. This leads to situation where you need to crank longer time, to get enough pressure to rail, because ECU does not allow injection until certain pressure levele is reached. If you try to do two ingntion cycles - ignition to 1 - wait glow plug light shut down - igntition to zero - ingnition to 1 - wait glow plug indicator shut down and immediately then put ignition to start - should start right away.

You have probably inner leak somewhere, I would bet injectors. Then it could be clogged fuel filter, clogged primer pump but these would cause problems in driving too.

Mersum 1es - thank you again! But, fuel filter is new- Mann, injectors are tested on mashine- in norm are. I can’t smell diesel, and there I can’t see leak, o - ring for back fuel are too new. Fuel consump is normal, I ty- 15/100 in the city/ Sofia- heavy traffic/ and 9-10 ltr/100 highly with 110- 120km/h

 

[onefortheroad]

Mersum 1es - thank you again! But, fuel filter is new- Mann, injectors are tested on mashine- in norm are. I can’t smell diesel, and there I can’t see leak, o - ring for back fuel are too new. Fuel consump is normal, I ty- 15/100 in the city/ Sofia- heavy traffic/ and 9-10 ltr/100 highly with 110- 120km/h

Fuel pressure drops overnight in the system , leaking fuel back to fuel tank , not external leak . Try 2 ignition cycles as you were advised earlier and see if things improve. Not to use glow plugs twice but to prime the fuel system ready for initial start . If it does start instantly with 2 ign cycles ,then almost certainly your losing fuel pressure internally via a fuel pump etc overnight.

 

[Martoname]

Thank you Onefortheroad, will try 2 cycles whithut glow plugs and will write after test.

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[Martoname]

Fuel pressure drops overnight in the system , leaking fuel back to fuel tank , not external leak . Try 2 ignition cycles as you were advised earlier and see if things improve. Not to use glow plugs twice but to prime the fuel system ready for initial start . If it does start instantly with 2 ign cycles ,then almost certainly your losing fuel pressure internally via a fuel pump etc overnight.

onefortheroad​

hi!
Yesterday I disconnected the positive cable of the heating relay and gave contact, waiting 5-6 seconds. I then attached the power wire to the spark plug relay and tried to start right after the light went out, but the car had a hard time starting again. Apparently the problem isn't the pressure