2002 1.9tdi AVF Hard Start

[Peter_222]

Hey,

ive had a Passat sport for just over a year now and it's always had a problem starting, in that it will crank a varying amount of time before eventually starting. When I got the car it was intermittent and when left nose down seemed to start easier.

This is eventually got worse until car then failed to start at all. Brought to a local mechanic who put it on VCDS. He checked group 13 which showed injector 1 way off the chart in comparison. To cut a long story short after numerous second hand injectors not working he changed o rings on original injector and the car started ok but still not on the button. About a week or so later the starting again began to get slower.

After alternator going I eventually had another mechanic change all o rings of all injectors for me. Note he reused the hold down and rocker bolts against my judgement and car was starting pretty good for two weeks. Now it's once again very hard to start when left and even if only left for short periods.

I have checked lift lift pump which must have already been changed as its 2012. The tandem pump must also have been changed as its a 2013.

Please note when when I turn on ignition for ten times the car will start very easy and when I prime it using vcds it starts easy too.

Can anyone please tell me what is being worked once ignition is turned and how this effects the start. It seems like it needs the lift pump activated numerous times to build enough pressure to start the car.

Is is the tandem pump being activated when ignition is switched on or does this only happen when cranking? Nobody I talk to seems to fully understand how the fuel system works and I'm being told a lot of different things.

Any help would be much appreciated as I do like the car otherwise.

Peter

[zollaf]

first off, anyone that reuses those little injector, rocker shaft or cam cap bolts should be shot.. they will pull the thread out the head, rendering the head scrap unless you can bodge in a helicoil, which you can't always do. anyway, lift pump intank delivers fuel to tandem pump. in the head are 2 tubes, one feed, one return. feed is fed with fuel at 100 psi to the injectors. returns to tank via fuel cooler. rubber o ring seals leak and feed loses pressure straight to return, car won't start easily. top seal leaks, fuel enters engine oil, engine blows up. bottom copper seal leaks and combustion gas enters fuel, turns to sludge and blocks everything up. injectors are powered by the cam shaft that operates the rocker, pushes pluger down to create 20,000 psi. electronics open and close injector, 3 pre squirts on compression stroke to get the burn going, main power stroke then after squirts to completely burn fuel and get more power/ cleaner emissions. injector harness breaks down causing misfires but beforehand loses pre and post squirts.. injectors vibrate in their bores and wear the head and injector. injector removed, new o rings, injector pushed into head, seal tears on sharp wear ridge, seal leaks. ridges can be smoothed out with wet n' dry and this can work, depending on how good its done. the bits where the seals actually seal doesn't wear, so they can still seal. this is probably whats up with yours and i bet the person thats done the work wouldn't notice as hes obviously not familiar with a pd.

[niall campbell]

have you changed the glow plugs ?

when you turn the ignition on, wait 2 seconds after the light goes out before cranking over as the glow plugs are still heating up, and using this method all year is supposed to prolong the life of the glow plugs

NGK or Bosch is what I would use.

In really cold weather, even turning the ignition on twice before starting car really helps starting if your glow plugs are beginning to fail.

Some of the modern VW Group of cars need a fast turn over of the starter for the ecu to tell the fuel to start pumping, but I think your age of car wont need this. I might be wrong

My 2006 A6 parked on a slope in either direction overnight takes a bit longer than normal to start & did so even at 9,000 miles on the clock, I just live with it.

You could check connections at filter for leaks ,, replace filter and smear oil on O rubber ring on top of filter and the small O rings on return/ flow pipes if needed .

VCDS should be able to check glow plugs ................ or replace them

[Peter_222]

Do you think if I got the injectors pulled out re sealed and bolted down with new bolts it could salvage or would damage already be done?

[zollaf]

you may be lucky, but its worth a try. hopefully the person that did it didn't torque the bolts up properly. the injectors are something like 7nm then 270 degrees. not many people have a torque wrench that will accurately do 7nm. 270 degrees is easy, 3/4 of a circle. all you can do is use new bolts and hope the threads hold. from audi all the bolts are about 150 quid. seals are 40 quid an injector. there is an ebay seller in poland does genuine bosch seals for a tenner an injector and i have used these a few times. they come in bosch bags, easy to identify. i would check the injector bores very carefully, and if rough , smooth out with wet n dry, plug the hole in the bottom to stop debris going in and use oil to lubricate, not water. i would rule glow plugs out as a pd will start at just above freezing on the first turn without plugs. sounds like the fuel pressure is being lost. there is a port on the tandem pump where you can connect a fuel pressure tester and you can also undo the bleed on top of the fileter to ensure a good flow of diesel comes out when the ign is switched on. the in tank pump should run for a second or 2, then off, then come on again when cranking. the seals are an easy job to do but also very easy to screw up. also then check the injector preload. tighten the adjuster at peak lift until it goes tight, then back off 270 degrees, ( or is it 180 ???? )

[Peter_222]

The fella should have known he was a vw mechanic for ten years. He assured me the bolts were grand and could be used again. I know the injectors were not original so the damage may well have been done already. Can you tell by looking and feeling the bores if there is any damage and what grit of wet and dry would you use?

[Peter_222]

Also just wondering why turning on lift pump ten times would allow the car to start up ok if that's not building any pressure in the head??

[zollaf]

he is a muppet then. yes, the bores should be smooth. if not perfectly smooth you will find rough rings around them, 3 in total iirc. as the seasl slide over these they tear. a torn o ring nada seal. use 600 grit on a finger or rotary tool. and make them smooth. the injectors don't matter but just remove the rough edges so you don't tear the seals when you fit them to the injectors. the bores may be perfect, you just don't know. the bolts, like most bolts on a vag, are stretch bolts, use once only. an m12 bolt you can get away with, they don't strectch much. these little m6 ones do, a lot. you will feel when you torque them down.

[zollaf]

Also just wondering why turning on lift pump ten times would allow the car to start up ok if that's not building any pressure in the head??

fuel leaks out of head, air drawn in. operate lift pump, pushes air out, fuel in, car starts. maybe..

[Peter_222]

After reading similar problems on numerous threads and the advice given from the likes of crasher I've asked about ten mechanics about changing the bolts and not one have said they do it.... It must be a Northern Ireland thing... I really need to get a good vw indie in NI that appreciates the details. This car has been a real stress as no one will do what I ask. Thanks for the advice. I just think a new head might be a simpler job. I can see one fully loaded from dark side developments £800 all in which is still good value as I want to keep the car for years.