Golf 5 1.9(BKC) cold start problems

Dieselmad

Well-known member
Joined
Sep 22, 2011
Location
Fochville, South Africa
TDI
Jetta MK4 1.9Tdi,
Hi all as you can see i am new here and i think this is a awesome site to be when talking about vw diesels. OK i recently bought a 2004 golf mk 5 1.9 tdi with the BKC pd motor. I am experiencing a cold start problem. What happens is the motor cranks for about 5 seconds before taking. It is if it start to take on one cylinder then on two then on all four. What i have tested is that when i unplug the temperature sensor then it will start immediately like normal. When the motor is on working temp then i don't have a problem, it starts immediately. Could it be a timing problem or some faulty sensor somewhere? Thanks for any input in advance.
 

Bambur

Well-known member
Joined
Apr 14, 2009
Location
Finland
TDI
Audi A3 (8PA), BKC w/o DPF, 2005
What's the ambient temperature when you have troubles cold-starting? It might be that your glow-plugs are dead and you have to replace them (but you say they are good though).

Another thing is that your battery might be quite old already and not delivering enough current, so it takes a while for starter to take to the minimum starting RPM. If the RPM is low, there is no fuel injected at all.

The fuel temperature sensor is known to fail often in this engine as well.

The crankshaft position sensor might be malfunctioning and it takes time while the ECU finds its position. There is also the engine speed sensor that might fail.

I would suggest to scan the engine fault memory with VCDS first, and see if there are any faults written, then check what values sensors give, and finally log the start to check what RPM you get.
 
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Dieselmad

Well-known member
Joined
Sep 22, 2011
Location
Fochville, South Africa
TDI
Jetta MK4 1.9Tdi,
Thanks Bambur, the temperature is about 16 degrees outside. The battery is brand new. The cranking speed is high as i can hear but will check the exact speed next time. How can i test the fuel temp sensor? Will do a scan again to see what fault codes come up.
 

Bambur

Well-known member
Joined
Apr 14, 2009
Location
Finland
TDI
Audi A3 (8PA), BKC w/o DPF, 2005
16 degrees Celsius or Fahrenheit? I haven't been to South Africa, sorry.

The fuel temperature sensor G81 is easy to check by common sense -- just compare what temperature sensors read, see the following screenshot of a faulty G81 below.

http://vwts.ru/images/repair4/142798_01.jpg


The temperature sensors' readings should be consistent when everything is OK as follows. Fuel temperature sensor readings should be close to the coolant temperature sensor readings.



Here is the whole story of my adventure with G81 -- http://translate.google.com/translate?sl=auto&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Fvolkswagen.msk.ru%2Fforum%2Findex.php%3Fshowtopic%3D142798
 

Dieselmad

Well-known member
Joined
Sep 22, 2011
Location
Fochville, South Africa
TDI
Jetta MK4 1.9Tdi,
Thanks Bambur, that's a great write-up you got there. I will check that when i got a change. O by the way, the crank speed is about 400 rpm and i meant 16 degrees celsius, sorry for that.
 

Bambur

Well-known member
Joined
Apr 14, 2009
Location
Finland
TDI
Audi A3 (8PA), BKC w/o DPF, 2005
16 degrees Celsius is warm enough not to think of the glow-plugs. They are off anyway always at that temperature. On the other hand 400 RPM is fast enough to enable ECU injecting fuel.

As a second thought I would suggest to check the fuel lift pump in the fuel tank. In case it malfunctions, it would take some time for the tandem pump to get the fuel off the fuel filter and tank when cold-starting, i.e. after the engine has been off for a while. When hot-starting, there is still some fuel left in the tandem pump and the fuel supply rails. Anyhow, you should check what fault codes are in the ECU memory first. That would help a lot.
 
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Dieselmad

Well-known member
Joined
Sep 22, 2011
Location
Fochville, South Africa
TDI
Jetta MK4 1.9Tdi,
I checked for fault codes but there is nothing. Could it be the diesel filter? I don't know the history of the car and i checked the service history but cant see if the filter was changed or not.
 

apples12

Veteran Member
Joined
Feb 1, 2011
Location
Birmingham, United Kingdom
TDI
Mk5 1.9tdi Match, BMW F10 520D
Hi,
I had this problem and installed a fuel check valve, after the ****ty valve failed because it wasnt suitable for high pressure systems, i removed it and the car ran fine for a while, now however, the rough starting has come back exactly as you describe, sounds like its not firing on all 4 cylinders straight away and same engine code etc etc

i am going to try changing sensor G81 and see how it goes from there and update back,
Hope you get your issue resolved

:)
 

apples12

Veteran Member
Joined
Feb 1, 2011
Location
Birmingham, United Kingdom
TDI
Mk5 1.9tdi Match, BMW F10 520D
Hi,
Well i got into the car this morning and before starting, began to log channel 001/007 and the fuel temperature was pretty much in line with the coolant temperature and ambient temperature

I can't for the life of me find a one-way valve suitable for high pressure fuel systems with a 3/8 or 1/2 fitting suitable for the fuel lines.

I did have a peek at the fuel temperature sensor and i did notice that the hose close to the temperature valve looked like it was 'saturated' with some sort of liquid (assuming diesel, it looked 'wet')

so I dont know if it may be an idea for me to go ahead and replace all the fuel lines in the engine bay with fresh ones and see what happens.

basically, the problem that I have is that when starting the engine first thing in the morning its very 'choppy' for about 10seconds then it stabilises out.

also, sometimes i'll crank, it will fire, run for a second or two then cut out. after this it will take 6/7/8 cranks to get it to fire and run...
 

Bambur

Well-known member
Joined
Apr 14, 2009
Location
Finland
TDI
Audi A3 (8PA), BKC w/o DPF, 2005
I checked for fault codes but there is nothing. Could it be the diesel filter? I don't know the history of the car and i checked the service history but cant see if the filter was changed or not.
Did you check the fuel lift-pump in the tank works fine?

The fuel filter should be changed around 60000-90000 km.
 

apples12

Veteran Member
Joined
Feb 1, 2011
Location
Birmingham, United Kingdom
TDI
Mk5 1.9tdi Match, BMW F10 520D
Hi Dieselmad,
just thought i'd post back that so far my tdi has had its cold start issue fixed...

despite my mechanic changing the fuel filter...i thought i'd have a go at changing the filter myself, not that difficult to do, all you need is a lot of rags and a T30 screwdriver/torx key

i noticed after removing the filter top and the filter element itself that there was a 'sludge' at the bottom of the filter...

remove the actual filter housing itself, it just pulls UP after you've removed the lid and put it to the side...

decant as much of the 'clean' diesel into a bottle as you can as you'll use this to help clean the bottom of the filter out

swill the diesel left at the bottom such as to suspend as much of the muck in the diesel and quickly chuck the diesel out, and get that filter housing as clean as possible!

replace a new filter element, new 'olympic ring' rubber seal, new rubber seal around the ring, replace the top back.

remove the top 'bleed' screw and replace the little metal washer under that bolt, with the bolt in but not tight, have someone cycle the ignition for 5-10seconds such as to prime the filter, you'll know its done because you'll get diesel bubbling around that bolt, tighten the bolt, cycle the ignition once more and start it, should be alright.

if that doesnt fix it, before you start the car in the mornings, cycle the ignition on, off, on, off, on and then crank to start the car... this i found worked for myself for some reason.

also consider getting your starter motor tested.

good luck and please post back!
 

Dieselmad

Well-known member
Joined
Sep 22, 2011
Location
Fochville, South Africa
TDI
Jetta MK4 1.9Tdi,
@ Bambur how do one check the lift pump?
@Apples thanks for the tips. The guy where i bought the car from told me that he switched the ignition on and off a couple of times, then the car started better in the mornings. He believed that it was the glow plugs that needed to be heated again. So can it be a fuel pressure problem or a airlock in the diesel system or dirty filter(that i will check) or a faulty lift pump?
 

apples12

Veteran Member
Joined
Feb 1, 2011
Location
Birmingham, United Kingdom
TDI
Mk5 1.9tdi Match, BMW F10 520D
those are the exact same symptoms i was having

I changed all four glow plugs as i had 2 that were throwing codes, figured i'd rule out any future glow plug issues by just replacing the entire set

the lift pump very rarely goes according to my mechanic...rule out any leaky hoses/cracked hoses etc etc before going down that route

is the diesel that your using a good quality one?
 

apples12

Veteran Member
Joined
Feb 1, 2011
Location
Birmingham, United Kingdom
TDI
Mk5 1.9tdi Match, BMW F10 520D
check and change fuel filter, inspect all the fuel lines in the engine bay for perished rubber...i've been told the rubber in the hoses can potentially perish if concentrated screenwash is spilt on it...

ideally pour in a bottle of diesel additive, i use Forte diesel additive, poured in a whole bottle (designed to treat 100L of diesel) into my tank, filled up with 30L, ran this through and repeated this once more, the engine is now running much much much much smoother on a cold start, no more bucking bronco engine in the mornings!

get your car scanned for glow plug codes, do you have access to a vagcom?
 

Bambur

Well-known member
Joined
Apr 14, 2009
Location
Finland
TDI
Audi A3 (8PA), BKC w/o DPF, 2005
@ Bambur how do one check the lift pump?
@Apples thanks for the tips. The guy where i bought the car from told me that he switched the ignition on and off a couple of times, then the car started better in the mornings. He believed that it was the glow plugs that needed to be heated again. So can it be a fuel pressure problem or a airlock in the diesel system or dirty filter(that i will check) or a faulty lift pump?
Whenever you switch the ignition key on, the lift pump in the tank is turned on for 1-2 seconds. If you unscrew the bleeding bolt on the fuel housing cap, you should see some fuel coming out. It's better to attach a peace of PVC hose to the bleeder and put it inside a bottle not to spill any fuel around. There might be no bleeding screw on your fuel filter cap, I have seen such cap variants too. Then you would need to remove the cap off the housing.

Here is my write-up on fuel filter element replace http://translate.google.com/transla...wagen.msk.ru/forum/index.php?showtopic=103734. If you do a search, there is also a thread on this forum as well.
 
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