Audi A3 '05, 2L TDI 16v BKD engine start problem

L

labanauskas

Guest
Hi, everyone,

I'm facing problem with cold engine start, when cranking it feels like like not all not enough or too much fuel and and cylinders misfire or smth...
Turning off and then starting again is way better.

The problem appears after a car stood still for over the night or couple of hours. Sometimes it starts without a problem 1/2 crank hot/cold...

Here's a video:
Dropbox - VID_20150224_074954.mp4

Injectors at idle stabilization:
Dropbox - jgkwghjwgh.PNG

Glow plugs are new, oil and filters(fuel, oil) changed 5000km ago.

No fault codes

Fuel temp, engine temp sensors show correct temperatures. Crankshaft and camshaft are good.

Torsion value 0.0/0.5 .

So what can cause such a problem? Tandem pump? Air leakage? Leaking injectors? ECU engine start map?
 
Battery is new Bosch S4 74Ah

How to check if it's starter problem?

Added cold engine start graph
 

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my car did the same to me i had a new alternator fitted havent had thr poblem since then even when left 3-4 days get a bosch one from.eurocar parts
 
I've had the same problem for over a year now.

New alternator, new battery, did the injectors (had bumpy idle), nothing really helped.

Then I remapped it so it is a bit better now, but sometimes it still happens. It can be due to porous cylinder head (coolant gets in) which is very common on these engines. Are you losing any coolant?
 
Somewhere in the back of my mind I'm recalling something to do with temperature sensors for a problem like this.
 
Rideen said:
I've had the same problem for over a year now.

New alternator, new battery, did the injectors (had bumpy idle), nothing really helped.

Then I remapped it so it is a bit better now, but sometimes it still happens. It can be due to porous cylinder head (coolant gets in) which is very common on these engines. Are you losing any coolant?
Click to expand...

No coolant is OK. VCDS reports correct temperature values from all sensors. Maybe it's a problem with aftermarket crankshaft sensor? Because I replaced it the faulty OEM with FAE aftermarket.
 
fouryoghurts said:
If starting signals are within spec & no faults, is fuel supply/holding pressure to spec pre/during cold cranking? When was fuel filter last renewed?
Click to expand...

And there's the question about fuel pressure... How to check on PD engine? Before fuel filter? Before tandem pump and etc... Fuel filter was changed 8k km ago.
 
This morning car started from a half crank... More than 1/2 fuel tank filled, in the garaze was 10c degrees. Strange
 
Well, I would have put my money on the Glow plugs as well. Try the simple things first, maybe water in the fuel tank, run the fuel tank down as far as you dare and then refill with a premium brand of fuel, change the fuel filter asap. See how she starts then.
 
No
Soot1 said:
Well, I would have put my money on the Glow plugs as well. Try the simple things first, maybe water in the fuel tank, run the fuel tank down as far as you dare and then refill with a premium brand of fuel, change the fuel filter asap. See how she starts then.
Click to expand...
No it's not the plugs, they are new.
 
labanauskas said:
No

No it's not the plugs, they are new.
Click to expand...

Yes, but are they pulling current to spec? Should be about 20A per plug if memory serves.

Regarding fuel pressure tests on the PD system - this really needs to be checked at the tandem pump test port (which needs a decent test pressure kit), and pre and post filter. +1 Soot1, change fuel filter if unsure of history/quality.
This system has a lift pump in the tank. You should make sure this is priming the system with ignition (a simple check: listen for pump operation above rear seats with key on). Next time you get a non-start try cycling the key on/off several times. This is fused, so basics first.
 
Last edited:
Yesterday morning with 1/2 fuel tank:

https://www.dropbox.com/s/dphe67mra9s6lyr/VID_20150520_065823.mp4?dl=0

Today still more than a 1/2 and started like yesterday.

Cycling key on/off doesn't help. I hear lift pump buzzing everytime, but no difference when starting. But like I mentioned keeping fuel tank more than 1/2 helps. I'll trye to test it for longer period.


What are specs for lift pump pressure? Maybe air is getting into fuel lines?
 
audi upgrades
labanauskas said:
But how about lift pump... How to check if it's holding the pressure and or how long it should be holding it?
Click to expand...

Lift pump should deliver 1l/30secs. Should run at 0.5bar @ idle / 0.25 @ fast idle (gauge inserted between fuel supply pipe and lift pump).
Re. holding pressure - the norm for a modern system is 30mins, but for this, so long as its priming effectively on the gauges it shouldn't be an issue.
 
But it's strange because the fuel filter is always full of fuel... How can air get into it?
 
UP.

Now in summer it's getting even longer to start the engine from cold/hot (doesn't make any big difference).
 
I'm currently having a similar issue with my '15 A3 1.8. Push starter. Was fine until my 5k service. Upon return, I had this issue...

Cold start always cranks for close to 2 seconds.. Then...

Sometimes it just immediately stalls
or
Sometimes it starts boggy and stalls.
or
Sometimes it starts boggy and goes to a high rev between 1k and 2.5k.
or
Sometimes it starts right up high rev.

I started using the garage to see if it's heat related since I'm in TX. Slight change, but not sure if it's related.

I'm noticing that my dash lights have a tendency to dim. It's barely noticeable.

Dealership can't duplicate issue.
 
I have had numerous issues since buying an A3 8PA 2005 BKD 2.0 16V engine a while back but by far the most frustrating was this starting and restarting issue both hot and cold. Went through this and similar threads but nothing sounded right so I decided to go for a re-map with a local person with good reputation. However before the re-map my issue was a hot restart that gave problems and after it switched to a cold restart problem! I researched a bit more being convinced that it was a software issue - which it is - and went back to the re-mapping place to complain. It transpired that although I told them there was a software issue they were not aware that there is a known issue and the "extra" file or addition to it should have been uploading together or with the initial re-map. I was not charged thankfully but once the update was applied it started like all cars should start and solved the issue instantly! I have no idea why it happened but as the car was second hand and quite "old" I am sure someone re-mapped it (possibly for power) and they did not ensure that the mapping file included the critical update in the past and just left it at that.

So get you car re-mapped but remapped PROPERLY!
 
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