2.0tdi BLB problems :(

adrenalin84

Registered User
Hi guys, kinda new to audisport, i briefly had a a6 c6 some time ago but now ive just picked up a 2006 a4 2.0tdi. Got some problems from the start. Heres what i know, any help would be much appreciated.

Outside symptoms :
Car is hesitant to start (always starts though)
Rough idle (but only when warm)
DTC : High limit fuel temperature sensor

So far i have installed a new fuel filter, new thermostat. It would appear there was nothing wrong with the old sensor and the high readings it was giving were correct. Over 100 degrees, and the fuel filter is noticeably warm
Through VDS i have observed block 13 injector deviation as -1.15mg/str 2.99mg/str -0.89mg/str -1.06/str.
The problem with cylinder 2 isnt always there it comes and goes but even when the readings appear okay it still has the lumpy idle and diesel smell.
Would a faulty injector case the high fuel temperatures?
The egr has been replaced recently before i got the car
 

CHEZ

moderately amusing
Supporter
Try changing your coolant temp sensor, not expensive, nor difficult to complete.
It's at the back of the block, opposite the bulk head, held in with a horse shoe clip.
It sorted my warm starting issue on mine.
Mine started OK cold, but would need a bit of cranking when warm, this sorted it, good luck (p. s. Do this when engine is cold to save burning your hands and wrists, little tip there lol)
 

adrenalin84

Registered User
Cheers chez I'll give that one a go next :) the readings from vcds seemed fine for the coolant though but I'll try anything
 

adrenalin84

Registered User
Just checked the temperatures from cold and readings are
Fuel 27 air 9 coolant 9 hmmm
Strangely if I disconnect the fuel temp sensor wiring I get a coolant g62 signal too high code, is this normal?
 
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JonSline

Considering the next mods.....
Have you got anywhere with your issues? I have very similar symptoms! Though I don't have vcds....
 

adrenalin84

Registered User
So far I have stripped out the injector in question (off to get refurbished) ordered a new injector loom and swapped temperature sensors. Will be a few days before I get the parts back and fitted to find out.
Back to work on Monday day so I hope to have it done before then
 

adrenalin84

Registered User
Nothing has changed, injector was tested and said to be working correctly although I now have a permanent coolant sensor high signal even though it has been changed
 
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JonSline

Considering the next mods.....
One of the other guys here had the same problem, I just read it. Apparently the fuel temp and coolant sensors can faulty/look the same but are not. May be worth double checking the part!? Also have you checked your MAF/MAP sensor.

I had some success in smoothing her out by playing with the timing.

Did you change the seals on the injectors. I'm thinking it could be the cause of my stutter when cold as when it's warm it's fine! Perhaps expansion seals the gap!
 

adrenalin84

Registered User
Changed the coolant sensor for an OEM one, appeared the two cables to the sensors had been swapped round for some reason in the past. Ran a can of moly purge through and the fuel coming back in the return line was extremely dirty. Don't know if this is due to the poor running for so long or the actual cause of the problem, another litre ordered. Seals on injectors would appear to be fine as the checks in the fuel filter etc don't appear to show any problems.
 

adrenalin84

Registered User
Meant to say, after replacing injector loom and coolant sensor the rough idle wasn't as bad as before but still present, still a strong diesel overfueling smell and smoke intermittently
 

JonSline

Considering the next mods.....
Overfueling like that especially in a diesel has to be maf related
 

adrenalin84

Registered User
The timing is at -0.5 so seems to be well within limits. It's only intermittent not constant so I'll give the map a clean this weekend, is there any specific resistance I should see?
 

JonSline

Considering the next mods.....
From what I read slightly advancing timing can have a positive effect on rough idle. Since you have a retarded timing this may have an effect. However it also changes the torque band of the engine. Changing it has had no effect on the specific symptoms on my engine apart from the described/expected results of changing timing!

Not sure on the expected resistance. I believe they kind of work or don't! I would clean both one at a time. It could well be the MAP as it's happing about where the boost is coming in.

I'll try cleaning mine if I can pick something up in belguim (whilst at work) suitable!
 

adrenalin84

Registered User
Cheer for the info I'll try all three this weekend hopefully. Another flush, map clean and maybe advance the timing
 

adrenalin84

Registered User
Well that's 1.5l of diesel purge ran through the car, the first 500ml was unbelievably dirty fuel being returned, don't know if that's a result of the rough idle sooting everything up but the shudder IS much less severe although still present. (Not had time for the cam advance and map sensor I couldn't find a security bit that would fit)
 

JonSline

Considering the next mods.....
Hmmmm interesting. Well I have ordered some diesel purge I'll try it. May cure it without removing injectors!


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adrenalin84

Registered User
I
Hmmmm interesting. Well I have ordered some diesel purge I'll try it. May cure it without removing injectors!


Sent from my iPhone using Tapatalk
Ran it straight, bought an inline filter and pulled the fuel pump fuse but if you have some fuel line lying around you could connect it in on the pump (pre fuel filter side)
 

JonSline

Considering the next mods.....
I

Ran it straight, bought an inline filter and pulled the fuel pump fuse but if you have some fuel line lying around you could connect it in on the pump (pre fuel filter side)

I think I'll probably just shove it in the filter and run it like that. Then change the filter after, although it's not all that old.


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Dan burns

Registered User
my car starts fine when cold and then once warm if stop to go to the shop or nip out for 5 mins it to struggles to start,could this be down to the CTS sensor? mines a 1.9tdi bke
 

JonSline

Considering the next mods.....
my car starts fine when cold and then once warm if stop to go to the shop or nip out for 5 mins it to struggles to start,could this be down to the CTS sensor? mines a 1.9tdi bke

Sounds like it to me. Isn't expensive or difficult to do. Group auto do them for a tenner


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Dan burns

Registered User
cheers @JonSline though i may get the mechanic to it as a 10 min job to someone else is a 3hour job and a lot of swearing to me..i was always told to buy the any sensors from audi by my mechanic as some other companys ones can be dodgey?
 
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