Running Issues at Cold

Funkyfin2000

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Hi Guys,

I've had this problem ever since having my 54 plate B6 Audi 1.9 TDi AVF 130bhp PD A4 Avant.

It's always been a poor runner for the first 5-10seconds of a COLD start. Never does the issue occur after a warm start or even if the car was used say in the morning and you use it in the afternoon. It's ALWAYS when left overnight.

Right...symptoms are....

Car Starts fine, no problem cranking etc....but once fired it runs very rough idle and quite noisy for about 5-10secs.

If you rev the car, it sounds quite noisy (i almost would call it "tapety") and if you pull away sometimes it very easily stalls.

The car ALWAYS with these rough starts, chucks out copious amounts of black smoke (which even this morning I thought looked a tiny bit blue - if that makes any difference)

This only happens at rough starts, don't get any black smoke on warm starts and no black smoke even when booting it or running it normally. It's a very un smokey TDI otherwise.

What I have done so far:

1. Replace glow plugs with bosch ones (this helped with a poor crank in the cold weather)
2. Had a full service, air filter, pollen filter, fuel filter and oil filter and oil change
3. Had the alternator pulley changed as this was knacered
4. Had the Coolant Temp Sender changed as knacered
5. Put injector cleaner through the car once (the good stuff)
6. Had the EGR valve and manifold cleaned (not that dirty anyway) but cleaned nonetheless.
7. Battery has been checked, running about 75% and recommendation this probably should be changed (get the brake warning light sometimes in the cold which is related to poor battery)
8. Had the electronic engine mount changed as this was throwing an error
9. VAG com shows NO errors at all.

So what other things could be a problem?

Battery for sure could be a cause

Possibly the injector loom but my understanding is this would throw up on VAG com (havn't had it checked as such physically)

Mechanic thinks the DMF could be showing signs of going, but not sure this could cause rough starts

Any help on this really appreciated....I really can't get to the bottom of it.

I have done an awful lot to try and diagnose but don't seem to be any better off. The things above have helped, it's not quite as bad as it use to be but still obvious.

It also seems to be worse in cold weather but it isn't always the case.

It's almost like a fuel starvation issue......

Cheers for reading!

Rich
 
black smoke is unburnt diesel, i know you have put injector cleaner through but it may be worth having them checked properly
 
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I dont know if this helps but my sons 2,5 TDI had something like this and he changed the injector with the needle lift sensor which has improved things but he still thinks that the fuel pump timing needs checking
 
One of the injectors has a sensor which monitors fuel flow in relation to the fuel pump and helps the two calibrate each other. I'm not sure if the PD engine works the same way though.
 
changed an injector with a needle lift sensor? Hi Mike could you tell me what that means?? Fuel pump timing can't be checked on the AVF 130 1.9

Your engine seems different but does it not have one injectorwith wiring to a sensor? VAGCOM should a fault on this on the 2.5
 
But I understood the wiring loom puts a vag com error.

Anyone got a guide on what needs doing to check the loom? Is it just a case of taking off the rocker cover?

A loom is an option to do....but not really sure that could cause this issue...although the misfire during running sounds like it, the rough starting when cold being worse....

I think the loom should be done possibly....and maybe a new battery.....to see if that improves it.....
 
mine dont and before i took mine out to clean it i was getting what felt like a missfire and it was not showing up at all
 
yes mine is the 1.9 tdi i did not take the loom out all i did was take the rocker cover off and pull the clips off the injector cleand them best i could and put them back worked a treat reson i did not take the loom out was if i was going to the truble of that id best spend the 50 ish on a new one and bin the old one but as it turnd out i was just testing to see if it would help as i could not see how it would but it did lol
 
yep that strate forward mate well thats all i did lol just get a new ruber gasgit for it though and some seler job done
 
Mine is a 130 AWX and sometimes does this!

Also have noticed the last week or so when stationery there's a lot of wobble coming through the car at tickover!
 
could well be the inj loom too mate mine did this
 
you will have to let us all no if it was this ;-)
 
Well, Cam lobes fine...no wear there..... loom has been replaced and of course visably old one looked fine but wasn't already uprated so its now got the new loom in it!

Ran quite nicely home but thats no test, need to leave it over night and see what happens.

Mechanic thinks possibly could be a tandom fuel pump issue.....reason being its ONLY a problem when the car has been left overnight so fuel pressure has dropped......apparantly theres a seal in the fuel pump that can go and let it loose pressure.

Changing the fuel pump will be a tart tho!!!

Will update tomorrow and let you know how I get on!!!

Rich
 
I have what seems to be the exact same problem so look forward to reading tomorrows update, hope this finally sorts it out :thumbsup:
 
Just the ****** same this morning!!

Got to be the tandem pump? Anyone confirm if a lift pump in the tank as well???

On a long run again today and letting off the gas about 2000RPM it definetly misses a beat!!!

****** annoying this!

How much for a tandem fuel pump!? £££££ i guess!!!

******!
 
Have you checked the timing? I.e line everything up, insert the locking pins etc?

I ask as on my older non-pd 1.9tdi suffered from poor cold start running but only after changing the cam belt. The timing was only slightly out but it made all the difference to cold starts but other than that the engine ran fine. On speaking to a VAG diesel expert he said it does this as the initial startup timing is mechanically set and then once its running the electronics take over and adjust the timing electronically to smooth things out.
 
Nope timing was checked and it is spot on! Done at Audi so would hope done properly.

There is a feeling its a leaking gasket in the tandem fuel pump!

GEtting a price to have it replaced.

Anyone done ANY work on a tandem fuel pump before?

Guys that are having the same issue - what have you done to look at the problem?
 
Nought TBH Rich, when I actually get some time I'm just going to book it into Staffs Audi / Midland VW & let them have a tinker.....sorry I couldn't be more helpful !
 
Be interested if you get it sorted.

Ive seen on one thread about parking nose down and nose up making a difference. I'm finding it difficult to check as my drive is all flat....

Im going to get the gaskets changed in the fuel tandem pump (£55 @ BVR Automotive in Stoke) and see how we go..

Where u based in Staffs? Im near Hixon/Weston area....
 
On the positive side, think of how many new parts your car has now Rich :haha:
 
For sure!! Sadly this morning it was just as bad........its funny.....it just runs rough as soon as it starts and bluey/black smoke piles out the exhausts and then it just picks up and the smoke stops after about 15-20secs!!! Very evry odd!!

When are you gonig down MidVW with yours!!!!! Come on....i'm out of ideas now :(
 
Apologies if this repeated, I've not go time to read back over the whole thread. There's not oil running down into the injectors/glowplugs from anywhere is there? This oil mixed with the diesel would then burn in the first few seconds when the car is started.
 
Nope no oil running down....thought that the tandem pump seal might have been leaking internally but sadly not......injector seals could be another area?

Gioing to get some more injector cleaner for it but it made no difference at all last time. Will get a video of this added to the thread again over the weekend.

the Car looses no oil and no water. Its fully serviced and otherwise returns great MPG and runs fine bar this little misfire around 2000RPM it sometimes gets when running on long journeys...

Rich