2.5TDi Cold Starting

AlexGSi2000

AlexGSi2000

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Now that the cold weather has come, Iv noticed that the 2.5TDi is taking longer to start than usual - but just want to make sure this is normal?

The glow plugs come on, I let the light extinguish and then crank for about 3 seconds until it starts - I get a plume of grey smoke from the back when it starts firing.

There are no signs of leaking diesel, fuel pump is timed within spec, im thinking about ordering new injector-leak down pipes and copper washers incase there is any air getting in - but if its normal for the 2.5 to take longer to crank then I will leave it.
 
I bought my 2.5 tdi back in febuary and when I bought it it took a while to fire up in the cold, when summer hit it was fine, started immediately but now its cold it cranks over for afew seconds before fireing, I'm pretty sure its quite normal on most diesel engines, the smoke is just a build up of diesel due to it cranking over afew time even my dads 62 plate cmax diesel is cranking over afew times in the cold with abit of smoke out the exhaust. I wouldn't worry about it unless it gets really bad mayb change the coolant temp sensor :)
 
audi upgrades
Mine starts first time almost always but this wasnt the case before the timing was adjusted last year when the belts were changed
 
My allroad starts first turn of the key, it's had new cams and lifters and a new cambelt for good measure... Also Martin's a6(fj twelve) also starts first turn of the key and that's on a 240k car. Don't know how many miles on this engine, all i know if it's adjusted fine, has good compression and working glow plugs then it should fire right away ! Might be a good idea to adjust the timing to or as close as to the top line...
 
Thanks for the advice - engine is on 136k but had new cams, lifters, rockers.etc 10k ago.
It was fine after the rebuild but now its colder it just seems to take longer.
 
Defo check out the glow plugs, mine was a bit lumpy last winter, 3 out of the 4 plugs were dead... still started tho..
Pull the connectors off them and check their resistance, should be just under an ohm..although I'm not sure about the ceramic glow plugs if you have them, would still imagine fairly low, check they all read the same..
 
In my experience there are a few things that can affect this, a well sorted V6 TDi will start first turn after the glowplugs have gone out.

A weak battery will have a big effect, the reduction in cranking power will lower the combustion, this delaying the ignition of the fuel. Have you had the three beeps showing low voltage at the ABS pump at all? If so, then I'd factor in a new battery fairly soon. The CTS (coolant temp sensor) can fool the car into thinking the engine is warmer than it is. Old glowplugs are another issue that will delay ignition. Also fuel pump timing, it only needs to be a fraction out for that difference to be exaggerated at cooler temperatures.

As mentioned, the smoke is unburnt fuel as a result of excess fuel being pumped into the chamber prior to ignition.
 
quattrojames said:
In my experience there are a few things that can affect this, a well sorted V6 TDi will start first turn after the glowplugs have gone out.

A weak battery will have a big effect, the reduction in cranking power will lower the combustion, this delaying the ignition of the fuel. Have you had the three beeps showing low voltage at the ABS pump at all? If so, then I'd factor in a new battery fairly soon. The CTS (coolant temp sensor) can fool the car into thinking the engine is warmer than it is. Old glowplugs are another issue that will delay ignition. Also fuel pump timing, it only needs to be a fraction out for that difference to be exaggerated at cooler temperatures.
As mentioned, the smoke is unburnt fuel as a result of excess fuel being pumped into the chamber prior to ignition.
Click to expand...
Hmm interesting, I've had the abs 3 beeps and thought my fluid was low as my abs was fine and even vcds didn't ping up anything. May check my battery indercator and see if its still green!
 
I've just come to live with this in the cold weather. Mines had a new battery, new glow plugs, new CTS and it was re-timed when I had the cambelt done. Maybe the timing is slightly out on mine but it drives perfect and the MPG is fine too.
All those bits needed doing by the way, I didn't do them to cure cold starting problems.
 
The timing seems to need an expert touch .Thats the impression I got when I watched it done on mine.It was over one cog out but it still ran well just lousy starting
 
Mine started beeping around the June time when I brought the car so the normal Chat on here says the battery, mine had the larger battery out the 2 specs being the diesel and bobs your uncle cured the 3 beeps on cranking but when it started dropping cold then it did do it around 6 times through the winter checked all wiring to starter battery and alternator for loose connections etc but I put it down to a old starter using plenty of juice cranking I'm sure we was low 9 cranking in winter
 
Thanks for the advice - The battery is 9 months old, had the multimeter out and still shows 13.4v after 24hours.

In regards to the glow plugs - I have no record of them being changed, so they may well be to blame - would dead glowplugs not keep the glow plug symbol illuminated on the dash all the time? (my previous vectra did this)

I will probably order new plugs along with all leak-off pipes and copper washers just to be sure.
 
from my experience, you may have 6 glow plugs working but one or two of them may be using more power to get to that glowing state due to the resistance levels, that or a dead glow plug will not help with the start up, a new set would be advised because if one has gone, how long before the others are failing you too, they all would have done the same time,
 
It's usually a timing or compression issue, glow plugs will manifest by uneven idling as soon as the engine starts + acrid smell of unburnt fuel... We're the injectors done ?
 
adamss24 said:
It's usually a timing or compression issue, glow plugs will manifest by uneven idling as soon as the engine starts + acrid smell of unburnt fuel... We're the injectors done ?
Click to expand...

Timing seems fine now, as the engine was a lot more responsive after the cams where changed.
Fuel pump timing is fine when looking at VCDS (in-between the middle and top line) - I had to replace the 3rd injector a few months ago as the needle lift sensor was broken.

You can smell a little unburnt fuel on start-up + grey smoke for about 5 seconds before it clears.

As far as the rest of the engine goes, I put a little 2-stroke oil in every tank, the EGR is blanked off, both intake manifolds de-coked and it gets fresh 5-40w (ester based synthetic) oil every 6,000 miles.

I purchased these last night;
6x NGK NTK Diesel D Heater Glow Plugs AUDI A4 2.5 V6 TDI 98-- 04 #3786 | eBay
 
AlexGSi2000 said:
Timing seems fine now, as the engine was a lot more responsive after the cams where changed.
Fuel pump timing is fine when looking at VCDS (in-between the middle and top line) - I had to replace the 3rd injector a few months ago as the needle lift sensor was broken.

You can smell a little unburnt fuel on start-up + grey smoke for about 5 seconds before it clears.

As far as the rest of the engine goes, I put a little 2-stroke oil in every tank, the EGR is blanked off, both intake manifolds de-coked and it gets fresh 5-40w (ester based synthetic) oil every 6,000 miles.

I purchased these last night;
6x NGK NTK Diesel D Heater Glow Plugs AUDI A4 2.5 V6 TDI 98-- 04 #3786 | eBay
Click to expand...

they will be a nice touch, let us know how you get on, what's the 2 stroke oil do to the fuel and how much do you use ?
 
Turkster said:
they will be a nice touch, let us know how you get on, what's the 2 stroke oil do to the fuel and how much do you use ?
Click to expand...

Will do.
A few people use 2-stroke in diesel now. The main point is to aid the lubrication of the fuel pump, modern diesels contain less sulfur and less lubrication properties.
To be honest, I haven't noticed much in regards to MPG, probably about 0.5mpg increase - I used to get a lot of soot out the back but since I have been using 2-stroke there has been a lot less. I tend to use about 400ml to 50 liters of fuel.
 
Don't trust those indicators in the battery, they are just a gimmick, I've had a few batteries that still have the green ball showing but they have been totally knackered.
Get a voltage meter on it and see if there is any drop in voltage.
Sorry just seen the other 2 pages of this thread think this has already been said lol.
 
Get yourself some plus gas and soak them for a few days. Do not force them as they are easy to snap in the head and will require drilling and helicoiling which is a head off job ! Also make sure you attempt to remove with a hot engine...
 
Just ordered new leak-off pipes, bolts, crush washers.etc - £87!... (eek!) - they need doing as the area is slightly damp with diesel.

Hopefully these bits combined with the glow plugs will sort it - if not it can stay that way!

Thanks for the advice Chris, I had fun and games trying to get the glowplugs out my vectra cdti last year - I was clenching my *** every time I turned them.
Iv got some penetrant spray so will spray them every day before I fit the new ones.
 
I was bored last night and needed something to do, so decided to fit the new NGK glow-plugs that arrived earlier during the day.

The old plugs had been soaked in penetrant spray twice over the last few days - all came out easily.

A few of the rubber surrounds on the glow-plug connections had perished and cracked, but the wiring seemed ok, so just carried on fitting them.

The ones that came out were made by Beru - im pretty sure I was testing them properly (the tip of the glow-plug to the positive side of the battery, negative to the middle body of the plug) but not one warmed up - they all seemed to be dead (yes, the battery was charged)

So quite possibly could have been the original ones fitted to the car?

Anyway, the car sat overnight, jumped in this-morning at -1.0c let the glow-plug light extinguish and it started perfectly - Started like it was warm, with no smoke - happy bunny!

I still have the leak-down pipework to do as it still seems to be weeping slightly (maybe when under load?) but will do those on Friday.
 
Yeah your testing them correctly m8 sounds like you've cracked it......
 
Crazy - all 6 being dead.
Would have expected it to be a lot worse when starting.
 
Wonder it started at all lol!

Well done gettin them swapped, I can remember how nervous I was when mine 'clicked' free ......
 
The Diesel engine runs at such high compression, if its been looked after and not to much worn out lol is should start some diesel set up run 9v glow plugs ans come on very quickly whilst cranking....... In your case you haven't got any compression issues...
 
marktdisport said:
The Diesel engine runs at such high compression, if its been looked after and not to much worn out lol is should start some diesel set up run 9v glow plugs ans come on very quickly whilst cranking....... In your case you haven't got any compression issues...
Click to expand...

Thats good to know - I have thrown a lot of money into this engine since I purchased the car, change ester based oil every 6,000 miles.etc
 
well thats good news, at least its not a compression issue mate, that would have been a real kick in the nuts, the fuel return pipes are easy to change and will make a nice clean look to the top end of the engine, When i did my pips i went all the way and dont the air sucking pipes to the egr and turbo unit all the other pipes of the same nature as they was all cracked and leaking all over the place, the engine responce was also improved by doing all that,

what about the Turbo unit iv got here ?
 
Turkster said:
the fuel return pipes are easy to change and will make a nice clean look to the top end of the engine.
what about the Turbo unit iv got here ?
Click to expand...

I have taken mine off a few times now to do various work, so yes a nice easy one.

Im going to have to make my excuses again - this time being the fact I haven't even started christmas shopping yet!
I will take the turbo off you but will be mid January if you still have it by then?
 
AlexGSi2000 said:
I have taken mine off a few times now to do various work, so yes a nice easy one.

Im going to have to make my excuses again - this time being the fact I haven't even started christmas shopping yet!
I will take the turbo off you but will be mid January if you still have it by then?
Click to expand...

no worries mate, i put it to one side for now then, :icon_thumright:
 
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