V6 tdi poor start with smoke

[neil bickerdike]

Hello all. Had the timing belt done along with full service in fuel filter.. as well as glow plugs
The car is hard to start amd when it does it has white smoke untill warm as well as a miss fire it seems. Found a injector feed loose as it was spraying out (guess the garage never tightened it)

Anyway when i go to start it it seems to miss fire and struggle starting as well as white smoke not condensation. It all clears when it is warm and the miss fire goes. Then it seems fine. Now and again it also seem to dip in reves on the motorway then oics up and all is well again.

The egr look blanked of from when i bought it a few years ago

Coming to a blank now so need help

 

[A19quattro]

I would run a diagnostic scan on it and see what it shows.
A few things are confusing, the most obvious being getting the timing belt changed; it doesn't have one.
I don't understand why the garage would have the injectors out or loosened, unless they were changing them?
When you say and injector feed I assume you mean the fuel pipe from the fuel rail to the injector?
White smoke is also strange, does it clear when the engine warms up?
Did it run OK before the "Service"?
EGR blanking shouldn't be a problem in it's self but if it is completely blanked then it should throw a code/engine management light in the dash but maybe it has been diagnostically coded out, would be good to know, not just guess.
Mis-fire could be Glow plugs but could also be a number of things which is why a scan would be a good idea, equally the smoke could be a few different things and a scan should tell you if they are related. If your Garage has charged you to change the timing belt, I would try to find another more reputable garage or someone on here, near you, to do the scan.
Hope this helps

 

[pauldazzle]

Coolant temp sensor would be one of my prime suspects.

 

[frankc]

B6 2.5tdi V6 engines do indeed have a timing belt...

and it's a tricky job getting the injection pump timing spot on after.

It sounds very like your pump timing is out, if the failed to tighten injector feed pipes I would be surprised if they have spent the time setting the pump timing properly.

The engine needs to be up to operating temperature and the dynamic timing measured on VCDS or the like and adjusted VERY carefully as each 0.5mm of movement on the injection pump sprocket equates to something like 1degree of timing and it doesn't take much error for the engine to run rough or be hard to start.

First things first, run diagnostics then check the dynamic pump timing with VCDS.

Frank

 

[A19quattro]

Ah, saw the B7 signature pic and assumed 3.0, oops!
Would still like to know answers to some of my questions,why are we removing injectors at a service and so on?

 

[neil bickerdike]

Thanks all for thr replays. New it had timing as i saw it. Glad we got that sorted out.
Its the parents car and was running fine since the timing i have said it has to be the pump out out a tooth or degree. However the white smoke DOES clear when it is warm and the missfire or lumpyness as well after a few minuites.
Then i think is it the pump as of that was out it woyld be all the time.

Then it is all fine till it is sat for a while or cold as well.

 

[neil bickerdike]

Coolant temp sensor would be one of my prime suspects.

What would that do

 

[A19quattro]

Tells the engine it's hotter or colder than it actually is and fuels accordingly, so either over or under fuels the engine.
Last bit of Frank's message above: "First things first, run diagnostics then check the dynamic pump timing with VCDS."

 

[frankc]

Duff coolant temperature sensors can make the ECU think the engine is colder or hotter than it actually is and affect fuelling.

The injection pump has a small amount of compensation to timing adjustments it can make which is possibly why your engine seems ok when warm. The best thing to do really is to get proper diagnostics run and check dynamic timing of the pump as you know that has recently been changed.

Edit - beaten to the post, literally!