1.6 TD is starting to get a bit smokey/bad starting...

[TylerDurden]

It sounds like you might benefit from a minor advance in timing.

In cooler weather, most of my vehicles run rough for a few minutes unless the CS is pulled. At idle, it can take longer to reach a temp where the engine will run smooth without the CS pulled.

I would mark the IP and bracket, then advance the timing a hair.

[ORCoaster]

Me too, Just mark a line across the top of the IP and the bracket and bump it towards the engine a tad. Then retighten and start with CS out then push in and see if it stays smooth.  Sounds like your CS is doing the adjustment for the amount of timing you need to have just to run it well.  Only need a pencil width of push to seperate the two marks.

[Bugsy_malone 666]

would the difference in timing have an impact on fuel economy by much?

Although I have been running this on veg oil, I have noticed the fuel economy was crap by any standard. It was around 27mpg on veg oil, reports show that while veg oil mpg is a bit less but I know my van previously has done 35-45mpg on average so its alot less!

[745 turbogreasel]

I never noticed any significant difference in power or economy.  The SVO has a bit less energy, but it's thicker, so the timing works better.

In ~10 years since i got my first Caddy, I've never had a working cold start on any VAG diesel, but it seldom freezes here.

For ****s and giggles, inspect and clean your out bolt.  It's easy, and if there is a debris or goo problem, you may well see it.

[TylerDurden]

Ja, my understanding is that significant improvement in fuel economy can result from timing optimization. Certainly, while the motor is stumbling, that ain't helping... but for some folks, getting the timing advanced to the point of clatter on initial pedal seems to be helpful.

My Westy is geared where high rpm are common, which is (AIUI) where injector lag is also common; so a bit of advance has helped maintain ~23mpg running D2. (A pretty fresh build too.)

[ORCoaster]

Bugsy and you others,

When I run the WVO in the Rabbit I have noticed power and mileage differences.  But not that bad.  My understanding is that you may see a 10% drop in mileage with the WVO compared to what you had going before.  That is 3.5 to 4.5 for what you had before.  27?  Nope notta right my friend. 

Now the pressure thing is a mixed blessing of sorts.  Sure it is thicker and thus advances the timing sooner and I think that might make up for part of the loss of power available from that fuel type.  But the injection of the slightly thicker fuel, granted it does sit on top the hot injectors before getting delivered but do we get the full boatload of charge we need?  I can't say, but what sort of performance to people get from going to what is called a veg oil nozzle?  Can't say there either just posing the question. 

Would the timing have that much effect on mileage you ask.  I see big differences in the car I drive with just 10 mm of change in the pump timing.  Getting the power screw and idle thrown into the equation and you can really change how the car runs and drives.  IF you want belching black smoke out the back to keep Hondas and such off your tail you probably aren't worried about 50 mpg.  Drive it like Gramps and maybe you will just have to let the rice burners rap past with those silly sounding exhausts. 

In addition to cleaning the out bolt you might have some success by tapping the regulator in a bit to get a few more pounds at idle.  That will carry all across the RPM band and might get you to full advance at 55 MPH.  Have you pulled any of the shims out from either side of the spring on the other side of the cold start?  That will get you advance as well. 

That is all for now.  DAS

[745 turbogreasel]

Now the pressure thing is a mixed blessing of sorts.  Sure it is thicker and thus advances the timing sooner and I think that might make up for part of the loss of power available from that fuel type.  But the injection of the slightly thicker fuel, granted it does sit on top the hot injectors before getting delivered but do we get the full boatload of charge we need?  I can't say, but what sort of performance to people get from going to what is called a veg oil nozzle?  Can't say there either just posing the question. 

My feeling is that if you can't get the same power on veg, something is wrong with your system.  Fuel not being almost at the same temp as the injectors going in would be one of those things.
filter restriction and air suckage seem to be most common though.

[TylerDurden]

^^^ Ain't VO supposed to be about 160F ahead of the IP?

[ORCoaster]

Yes Tyler it is supposed to be 160 going into the IP but what is the temp coming out and sitting in the lines and finally delivered to the cylinder.  I use a digital temp gauge on the fuel going into the pump and maybe I should swap it's location to being on the lines to the injectors instead.  I am sure there is a temp drop going on there.

AFAIK the 160 temp is for viscosity purposes.  To be more like diesel inside the pump, and to burn without using some of itself to get there. 

745 you got the air suckage and filter restriction properties right.  I heat the fuel prior to filtration because it wouldn't do very well pulling thick fuel into the filter.  Our diesel filters are better at doing their job under vacuum than with pressure pushing the fuel through them I believe. 

I use one of those oil coolers in reverse on the filter and then from there pass it to a FPHE to get it as hot as I can a foot from the IP.  Most times I am worried I will get it too hot, which isn't good either. 

If one has temperature loss that is excessive I suppose you could electrically heat the lines as there is a product for doing that.  With the low amp alternator I have I decided to double up on the coolant heaters instead.  Drop a 90 or 120 amp alternator on there and I wouldn't fret about it.

[745 turbogreasel]

Heated tank, more heated  fuel line...filter hurts to touch, and injectors run 160 at idle regardless of fuel according to my IR pyrometer.
No unusual deposits any time my engine has been apart.

[Bugsy_malone 666]

when you guys say 'out bolt' do you mean the bolt for the banjo fitting for the return line on the IP? just ordering a new 3mm return line from the injectors. then at the weekend I'll look at adjusting the IP timing by a few mm and see if its better.

[TylerDurden]

Yes, that bolt is marked on its top "OUT", because it has a screen inside and a small orifice that maintains IP internal pressure. It is calibrated with the pressure regulator at the front of the IP.

[Bugsy_malone 666]

Ok had chance to muck about with the vans engine today and check over a few suggestions.

Firstly I replaced the knackered injector return to fuel pump line, while doing so I took the 'outbolt' off and had a look, clean as a whistle inside the bolt! and I saw the screen etc.

Next up I move the fuel pump timing marginally, bit of an arse to do on my van but I managed to twist the pump by a degree maybe (which is what I guess a pencils width to be) It wouldnt really move much anyway because of the injector pipes and stuff, but importantly it was only moved a tiny bit as suggested.

So temperature in the shade is currently about 6c, feels warmer in the sun like 8-9c not bitterly cold. With the cold start pulled out, turned on the ignition and waited for the glow plug light to go out, span the engine over which after a few spins fired put out a little puff of black smoke, threw the starter out but didnt start. So cycled the ignition a second time and it fired right up let it run for a few moments then started easing the cold start in and it ran fine on idle till the last 10mm of travel (the cable has about 50-60mm of travel to pull the cold start all the way out) at which point it started to stumble and smoke a little.

So I picked the revs up from idle to maybe 1200rpm and it was just blue smoke city worse than at idle and it would miss (which I find odd for a diesel), pick the revs up further to say about 1800rpm and it runs fine on 4cyl but there was a constant slight haze coming from the exhaust although I couldnt tell if it was blue or grey(probably blue) but it was running 'fine' at high revs. Then I let it idle again, at which point I put the CS right off and it idled fine just a little smokey, but if you picked the revs up to between 1000-1200rpm you'd get the issue with it missing a little, beyond that it would run alright back on 4 constant.

By this point the engine had a tiny bit of warmth in it and was running ok without the CS on, but still wasnt running very clean or as good as I think it could/should be.

I did at one stage turn the engine off, go round the back of the van and check the engine over and then go and start it up again and it started fine, without even pulling the CS out.

I have also found at revs I'd hold the revs at say 2000 and it would then start to pick up further on its own by maybe another 500rpm, I dont know if thats as a result of turbo pressure or what, but then if I let off just a fraction the revs would drop back to 2000ish and then start to die down to more like 1500rpm, maybe this is normal?

I'd say things are marginally better but something is still not right, and until it runs right stationary I dont want to take it out driving!

The thing that still concerns me is the blue haze it has. it makes me think something isnt burning properly, either because the injectors need reconditioning, the pumps not putting out the right pressure or not enough fuel maybe?

Thanks for all your help, I am open to more suggestions!

[TylerDurden]

I still rekon there is a bit of air getting into the IP, if there is a stumble. I haven't seen an engine stumble that wasn't due to air in the IP.

If you didn't purge the IP of air before the startup, there may have been some remaining from opening the lines.

But, it seems almost normal... all my rigs have a bit of haze in the exhaust until they are fully up to temp.

If you haven't already, loosen the hardlines at the IP and retighten to relieve the torque from moving the IP. That stress can cause lines to crack.

[Bugsy_malone 666]

Yeah tomorrow I might give that a go if I get chance and try maybe moving the IP a smidge more. Once it was warm it was much better than it had been, I still think it needs a bit more tuning and I certainly need to get the right spring to help return my cold start as that could prove invaluable with the freezing temps due next week.

Tomorrow If i have enough time I'll also do a check around the engine bays fuel lines and double check every thing is spot on.