2006 X5 Diesel intermittent cold start problem

[opienor]

Hi guys!

Well I´ve understood I´m not the only one with X5 start problems...
Never had any problems with my car, but a couple of weeks ago I started having problems starting it. It seems that the colder it gets outside the more pronounced the problem is. Here´s what happens:
I turn the key and all is fine. Everything lights up as usual and the DDE light indicates glowing. Then starter cranks just fine but there is no sign of ignition. I then have to completely turn the ignition off and try many more times before the engine suddenly fires.
I notice that every time the engine fires there is an extra pump buzzing sound when I engage the ignition. Hence it appears that the diesel pump fails to function every now and then. But what causes this? My car is at an official BMW dealer as we speak but they haven´t been able to recreate the problem and have no clues. The outside temperature is of course much higher now, so the problem doesn´t show up. Needless to say I´m getting a bit frustrated. Any ideas much appreciated!!

[powers1]

[QUOTE=opienor;812122]Hi guys!

.................. the DDE light indicates glowing. QUOTE]

Whats the outside temperature when this happens?Does the glow plugs light stay on while you are cranking ?
Do you have any error codes?
From a mechanical side,they shoud be looking at glow plugs first,injectors and then they should check the fuel pump pressure.

From an electrical side,they should check the crank sensor,fuel rail pressure sensor .

[opienor]

Thanks powers1!

The problem gradually intensifies as outside temperatures drop. Lower temps equal more start attempts. Worst case happended at -4 deg. Fahrenheit when the engine just wouldn´t start at all and the car had to be towed. I´d say the problem appears between approx. -4 to 23 degrees F.
I think you may be right about this being some sort of a sensor or electronics related problem. Especially since I can clearly hear that the fuel pump fails to activate the times the car doesn´t start. Something appears to be wrong in the startup sequence. I glow, fail to hear the pump, crank with no start. This is repeated a number of times until the pump (I assume) suddenly comes to life when ignition is activated, the glow light goes out and voila the engine starts. I have tried to go from off to ignition without cranking a number of times to see if the pump suddenly starts, but without any luck. The cranking (without start) somehow seems to "wake up" the pump for the next start attempt.
The glow indicator lights up and then goes out before I start cranking. Everything appears normal in that department. And no error codes I´m afraid.

[powers1]

Originally Posted by opienor

Thanks powers1!

The problem gradually intensifies as outside temperatures drop. Lower temps equal more start attempts. Worst case happended at -4 deg. Fahrenheit when the engine just wouldn´t start at all and the car had to be towed. I´d say the problem appears between approx. -4 to 23 degrees F.
I think you may be right about this being some sort of a sensor or electronics related problem. Especially since I can clearly hear that the fuel pump fails to activate the times the car doesn´t start. Something appears to be wrong in the startup sequence. I glow, fail to hear the pump, crank with no start. This is repeated a number of times until the pump (I assume) suddenly comes to life when ignition is activated, the glow light goes out and voila the engine starts. I have tried to go from off to ignition without cranking a number of times to see if the pump suddenly starts, but without any luck. The cranking (without start) somehow seems to "wake up" the pump for the next start attempt.
The glow indicator lights up and then goes out before I start cranking. Everything appears normal in that department. And no error codes I´m afraid.

Well,its when you dont get the error codes ,and the engine doesnt start,that the hard work starts
Have you tried waiting 25 secs before cranking the engine?This is about the time the glow plugs take to turn off and will give you more heat to burn the diesel and start the car.
The coolant sensor is also influencial in the start procedure,so get them to have a look at that.
Another thing is if your EGR valve is closed ,it wont allow air into your engine and it will starve and wont start.To test it,You can pull off the vacuum pipe to it and see if it makes a difference.
The best way and we do here is we do it by trial and error,by replacing the sensors I mentioned above.
Today ,we had a 330d E60 that wouldnt go above 2500 rpm when the engine coolant temp (ECT) was between 10-50 degrees...!After this temp, it was fine!No error codes !We replaced the obvious sensors...nothing!Tried the turbo solenoid and voilá...all good...
I leave you here a pic of all the sensors in the engine compartment.

[opienor]

Have you tried waiting 25 secs before cranking the engine?This is about the time the glow plugs take to turn off and will give you more heat to burn the diesel and start the car.

Haven´t tried that but will do. Does this glow period change with temperature or is it a standard 25 secs regardless? I didn´t know the glowing lasted that long. Always thought glowing stopped when light goes out. Thanks for teaching
With temps going way below zero F here in Norway during winter most diesel cars have a hard time every now and then. Mostly caused by dirty, clogged up and frozen fuel filters. Initially thought to be the problem with my car, but no.
The BMW guys continue their little investigation on my car tomorrow so crossing my fingers they will discover the reason. In the mean time my trusty 318i runs like a clock

Thanks a lot for taking the time powers1

[powers1]

Originally Posted by opienor

Haven´t tried that but will do. Does this glow period change with temperature or is it a standard 25 secs regardless? I didn´t know the glowing lasted that long. Always thought glowing stopped when light goes out. Thanks for teaching
With temps going way below zero F here in Norway during winter most diesel cars have a hard time every now and then. Mostly caused by dirty, clogged up and frozen fuel filters. Initially thought to be the problem with my car, but no.
The BMW guys continue their little investigation on my car tomorrow so crossing my fingers they will discover the reason. In the mean time my trusty 318i runs like a clock

Thanks a lot for taking the time powers1

Its not temperature related!Glow plugs go out when the Glow plug module switches off (about 25 secs) or when you crank the engine,whichever happens first.
Normally,when the plugs are going faulty,letting them be on for a few more secs,helps them heat-up more.This is also a sign that they need changing as they are either taking longer to heat-up or you have a faulty plug(s).
In anycase ,in extreme below freezing temperatures,its always best to wait a few more secs,before you crank it, after the glow plug light goes out.
Above freezing,they are almost redundant.

I hope the Bmw guys there do their job!
Keep us posted please

[X-ray Lima]

Did you ever wind up gettin this sorted out???

My '05 diesel has started playing the same game.

Yay.......

[opienor]

Originally Posted by X-ray Lima

Did you ever wind up gettin this sorted out???

My '05 diesel has started playing the same game.

Yay.......

I sure did! Meant to update this thread but never got around to doing so.

As stated in my last post the car went back in to the mechanic. It turned out that there was yet another relay also affecting the fuel pump. If I remember correctly this one sits behind the glove box. The mechanic changed it and opened the old one to find the contact surfaces were badly scorched (the other relay he changed earlier looked just fine on the inside by the way).
Evidently the relay worked OK when the air was warm and dry, but the problems kicked in with cold and humidity.
After this the problem was solved. Has started just fine ever since. The dealer only charged me a few bucks for the last relay and not for the job. Seems they were a little embarrassed they didn´t change both relays the first time around. After all I had described the problem to them in great detail.

Best of luck and do let us know how it goes!

[X-ray Lima]

Funny you should say that.....

After several hours of googling, I came to the conclusion that particular relay was the most likely (and cheapest) possible culprit for the symptoms.

Since the car played up about 5 times yesterday, I snatched it and went and picked up an OEM relay from BMW stealership and installed it yesterday arvo. My old relay looked a but old and sad too, but have seen worse operate ok.

Fingers crossed its fixed the problem. Started fine this morning and it was cold (for Perth). Another few days will tell the whole story I guess.

[omodos]

X-ray LIma old post, but did this relay replacement sort out your issue?