2006 Audi A3 TDI 170 DSG Starting issues - help!

[Paul_Paul]

Hello all,


I need some advice for my 2006 Audi A3 TDI 170 DSG. BMN Engine. 54K,

I'm going to have one last try to make some progress on this, before giving in and getting rid of it, which I really don't want to do right now due to a house renovation and the costs associated with that, and the fact I only do about 3K miles a year.


Summary of issues:

Difficult to start when cold. Really rough for 5-10 seconds.
Seems to crank slowly, especially noticeable when cold.
Difficult to start when the car has been left for a long time, irrespective of temperature. A week left in the Glastonbury carpark I nearly flattened the battery getting it to go. A month travelling, no chance. You can flatten the battery sometimes trying to start on the first key turn only if you are unaware of the issue, but priming it again on the second (or more) key turns can get it going straight away.
I never try now on the first turn of the key to ignition.
Now and again it will refuse to start at all, irrespective of key turns, until the battery is dead. If this happens I can get it going with Easy start up the air box, after recharging the battery.
Additionally (related or not) sometimes, there is a real shudder as the car kicks in, a lot of movement in the engine 50/50 maybe.
If it’s already been started once, it will usually start again no problem. Still has the shudder though sometimes, doesn’t seem to be related to whether it struggles starting or not.
It's been doing this for years now.
Runs absolutely great once started. No noise, vibrations or gear change issues.


The main aim here is to see if anyone can suggest a series of diagnostics I can run through to try and stop this turning into a £3000+ horror story, like a lot of the forums I have been reading with PD starting issues. I have a new VCDS on the way in the post, as my old cable broke.

New battery didn't make a difference.
New fuel filter.
Oil change.
I think there was one code the last time it was scanned- Engine speed sensor - implausible signal, but I cleared that and it didn't come back. Need to check again it is came back once my cable arrives.
The car had the Injector recall in Sept 2013. I can’t remember if it started after this (like many other forum posts have stated) but is it possible, it was so long ago. I asked this week what was done exactly on the recall and after a very long time they came back and said 4 injectors and loom. When I pressed for more info about seals, bolts etc. they said they would have been done too after ‘speaking to the manager’.

An independent Audi garage guy in Sheffield (sat in the seat and started it) suggested it felt like the DMF may need replacing because of the shudder, could this also cause the starting issues described? They said so. But I also read a poorly starting engine/slow crank can create a lot of movement in the DMF, so is that a side-effect of the real issue?

I saw this comment on one forum post "I've just read a thread that claims his pd170 cold start issues was caused by a faulty DMF!
Basically anything that affects injection timing will make cold starts difficult as the 170bhp engine is highly sensitive to timing."

I took it to a gearbox specialist who said he could change the DMF for £800, but he didn't fill me full of confidence he thought it definitely needs replacing. There isn't any noise or rattle running. He also said the DMF wouldn't affect the car starting on my model and I should concentrate on the starting issue, before committing to spend £800 on the DMF. So a little frustrating as I'm getting conflicting information. If there is no rattle noise and my DMF has failed does it mean it could be ceased. Can this be diagnosed? I saw one video on a guy who’d remove the starter and got a camera in there to check it out.

The bottom line is due to my situation I’m happy to spend a bit on this car (needs disks, pads and tyres too) as its never really given me any other issues, if I can work out what is wrong with it, and have another few years more life out of it. But I don't want to throw a load of cash swapping bits out that will not solve anything, and never getting to the root of the issue, then end up getting rid of it after that.

Quite happy to take it to a garage and pay for a few hours labour of additional diagnostic tests I am unable to do, to move it forward after advice here.

But, reading all the possible causes from these forums and problems people have had, I'm wondering whether to just give up.

I am no expert but looking at all the symptoms it feels like a fuel related issue somehow, directly or indirectly, at least for the starting issue anyway.

The possible topics mentioned in reading these forums for PD cold starting issues is worrying.

Injectors
Injector seals
Stretch-bolts
Fuel pump
lift pump
Sensors - temperature/crank sensors
Starter
Glow plugs


Any advice is much appreciated on how (if at all) I tackle this. I feel at the moment I need a bit more info to commit to spending some cash on it.

Paul

[lincolnzondi]

Hello all,


I need some advice for my 2006 Audi A3 TDI 170 DSG. BMN Engine. 54K,

I'm going to have one last try to make some progress on this, before giving in and getting rid of it, which I really don't want to do right now due to a house renovation and the costs associated with that, and the fact I only do about 3K miles a year.


Summary of issues:

Difficult to start when cold. Really rough for 5-10 seconds.
Seems to crank slowly, especially noticeable when cold.
Difficult to start when the car has been left for a long time, irrespective of temperature. A week left in the Glastonbury carpark I nearly flattened the battery getting it to go. A month travelling, no chance. You can flatten the battery sometimes trying to start on the first key turn only if you are unaware of the issue, but priming it again on the second (or more) key turns can get it going straight away.
I never try now on the first turn of the key to ignition.
Now and again it will refuse to start at all, irrespective of key turns, until the battery is dead. If this happens I can get it going with Easy start up the air box, after recharging the battery.
Additionally (related or not) sometimes, there is a real shudder as the car kicks in, a lot of movement in the engine 50/50 maybe.
If it’s already been started once, it will usually start again no problem. Still has the shudder though sometimes, doesn’t seem to be related to whether it struggles starting or not.
It's been doing this for years now.
Runs absolutely great once started. No noise, vibrations or gear change issues.


The main aim here is to see if anyone can suggest a series of diagnostics I can run through to try and stop this turning into a £3000+ horror story, like a lot of the forums I have been reading with PD starting issues. I have a new VCDS on the way in the post, as my old cable broke.

New battery didn't make a difference.
New fuel filter.
Oil change.
I think there was one code the last time it was scanned- Engine speed sensor - implausible signal, but I cleared that and it didn't come back. Need to check again it is came back once my cable arrives.
The car had the Injector recall in Sept 2013. I can’t remember if it started after this (like many other forum posts have stated) but is it possible, it was so long ago. I asked this week what was done exactly on the recall and after a very long time they came back and said 4 injectors and loom. When I pressed for more info about seals, bolts etc. they said they would have been done too after ‘speaking to the manager’.

An independent Audi garage guy in Sheffield (sat in the seat and started it) suggested it felt like the DMF may need replacing because of the shudder, could this also cause the starting issues described? They said so. But I also read a poorly starting engine/slow crank can create a lot of movement in the DMF, so is that a side-effect of the real issue?

I saw this comment on one forum post "I've just read a thread that claims his pd170 cold start issues was caused by a faulty DMF!
Basically anything that affects injection timing will make cold starts difficult as the 170bhp engine is highly sensitive to timing."

I took it to a gearbox specialist who said he could change the DMF for £800, but he didn't fill me full of confidence he thought it definitely needs replacing. There isn't any noise or rattle running. He also said the DMF wouldn't affect the car starting on my model and I should concentrate on the starting issue, before committing to spend £800 on the DMF. So a little frustrating as I'm getting conflicting information. If there is no rattle noise and my DMF has failed does it mean it could be ceased. Can this be diagnosed? I saw one video on a guy who’d remove the starter and got a camera in there to check it out.

The bottom line is due to my situation I’m happy to spend a bit on this car (needs disks, pads and tyres too) as its never really given me any other issues, if I can work out what is wrong with it, and have another few years more life out of it. But I don't want to throw a load of cash swapping bits out that will not solve anything, and never getting to the root of the issue, then end up getting rid of it after that.

Quite happy to take it to a garage and pay for a few hours labour of additional diagnostic tests I am unable to do, to move it forward after advice here.

But, reading all the possible causes from these forums and problems people have had, I'm wondering whether to just give up.

I am no expert but looking at all the symptoms it feels like a fuel related issue somehow, directly or indirectly, at least for the starting issue anyway.

The possible topics mentioned in reading these forums for PD cold starting issues is worrying.

Injectors
Injector seals
Stretch-bolts
Fuel pump
lift pump
Sensors - temperature/crank sensors
Starter
Glow plugs


Any advice is much appreciated on how (if at all) I tackle this. I feel at the moment I need a bit more info to commit to spending some cash on it.

Paul

I had a similar issue in my Astra a few years back, I couldn't be bothered to fix so I just flogged the thing. My main suspicion would be glow plugs though. Since it's a cold start only problem.

Sent from my HUAWEI VNS-L31 using Tapatalk

[Paul_Paul]

It’s not just a cold start issue. As mentioned, it also is affected by time. It very nearly wouldn’t start before the battery was depleted in the Glastonbury car park, as it was left for a week. I think that was the hottest week of the year.

[Crasher]

The BMN is becoming a bit of a dog in its old age, the symptoms you describe are classic for worn and damaged injector seating faces.

[Paul_Paul]

Wow thanks Crasher, that's a comprehensive reply, and something for me to get my teeth into. Thank you so much. Hopefully my VCDS cable will arrive soon.

Do you think I could have more than one issue here? Or just too early to tell and guess without more info? Just trying to tie in the sometimes really shaky engine start to the start-up fault. Are symptoms related to one issue ? I'm not a mechanic, but thinking about this logically, if I have bad starting and firing could this explain the shudder experienced sometimes, making others misdiagnose it. If everything isn't kicking in, in harmony so to speak, depending the position of the pistons in the cylinder at that time, and fuel not supposed to be where it should be, if drained back. My gut feeling it its all one issue, not the DMF. This is why I have been reluctant to follow previous advice to swap DMF, as I feel its an £800 gamble without good odds. I've lived with this issue for years. Its really annoying, but it's never seemed to progress to get worse than it is.
The only confusing bit is that I can drive for 2 hours on a motorway. pull in to the services say, then it starts immediately as everything is hot, but the massive shaky engine judder can be present as it fires up, or not.

I however, like the diagnostic approach above, nobody anywhere has suggested an approach like that to me yet.



The only difference from that bulletin is I'd say that I never have any warm starting issues really only cold.

To clarify, cold weather, very difficult to start, if say not used for 24 hours. Once started once, it will fire up again ok.

Hot weather, starts most times, if used recently.

Leave the car for a long time, difficult whatever the outside temperature, but most times if its hot weather you'll get it going eventually. Very cold weather probably not.

[Crasher]

The very first step is a code read, save the results, clear all the codes, drive it again for a few weeks and see what comes back and compare the results with the first scan.

[Paul_Paul]

Hi there,

OK got a VCDS cable....


Upon first read on the 17th July I got this.


1 Fault Found:
000801 - Engine Speed Sensor (G28)
P0321 - 006 - Implausible Signal - Intermittent
Freeze Frame:
Fault Status: 00000001
Fault Priority: 5
Fault Frequency: 3
Reset counter: 25
Mileage: 89127 km
Time Indication: 0
Date: 2019.07.09
Time: 06:35:56


Freeze Frame:
RPM: 160 /min
Torque: 0.0 Nm
Speed: 0.0 km/h
Time: 0.02 s
Angle: 0.0 ∞
Bin. Bits: 00000000
Bin. Bits: 00000001


Cleared the fault code....


Drove the car the following days consecutive days and although it started in its usual slow and lumpy way it started on the 2nd key turn after a few seconds (never try on there first) sometimes with the really shaky start, sometimes not.


Didn't use it all weekend until Sunday evening. Took 4 attempts and four key turns to finally get it going.




The same came back again after this start...




1 Fault Found:
000801 - Engine Speed Sensor (G28)
P0321 - 006 - Implausible Signal - Intermittent
Freeze Frame:
Fault Status: 00000001
Fault Priority: 5
Fault Frequency: 1
Reset counter: 40
Mileage: 89202 km
Time Indication: 0
Date: 2019.07.22
Time: 15:25:10


Freeze Frame:
RPM: 160 /min
Torque: 120.0 Nm
Speed: 0.0 km/h
Time: 0.01 s
Angle: 0.0 ∞
Bin. Bits: 00000000
Bin. Bits: 00000001

I'm pretty sure I had this sensor changed a few years ago, but will go back through my records to check.

Read on another post, this code can be thrown up due to a slow crank. It does seem really weak. Shall I move onto checking the speed in that doc above? What is that central plug in the instructions I need to remove? Thanks

[Crasher]

Do a cranking RPM test. Disconnect the injector harness at the head, FULLY charge the battery. Go into the engine measuring blocks and find a block that shows the engine rpm. Start cranking the engine over and keep going as it will take VCDS a few seconds to reestablish comms after you start cranking and then when it comes back up, note the RPM.