Narrowing down some hard start problems

GTE

Hello,

My car is a bit hard to start these days, the cold makes it a bit worse.

Its a 1.9 TDI90. AGR.

The battery was changed as apparently it was not keeping a charge properly and indeed the new battery does seem to have made a difference however with the car laying idle for about 24 hours and the first start in the cold or any time during the day I still have the problem I had in the first place.

The engine can take a few seconds to kick in and when it does I get the unburnt diesel smoke. The engine seems to catch a couple of times before it gets going.

The temp sensor was changed a while back and the guy at VW who diagnosed the battery said that the GP's shouldnt come on until 1 degree or -1degree and I dont think I have hit that yet.

The car sounds like this, especially when it starts sounding like its catching (15 - 16 secs), during crank but for me its about 3 - 5 seconds at the most. One the engine starts the idle is fine.
http://www.youtube.com/watch?v=YyhQQOEe0VM&feature=related

Every start after that, even if its only 30 seconds after the first one, is perfect.

Is it timing? The coolant sensor should be ok and the battery has to be. I dont have my diagnostics cable with me at the moment.
I may send it into that Eugene Walsh fellow soon to get it diagnosed.

Thanks

http://www.youtube.com/watch?v=dJg5vBEif58&feature=related
Pretty mad! Its half interesting how when the cylinders all warm up you eventually get a nice idle.
The good aul tractor!

Owen

Take out the glow plugs and see are they warming up. Next step is to check fuel pressure, after that, maybe it might be the crankshaft position sensor, but do the basic checks first.

Row

Maybe check the fuel pump supply hose....if theres a pin hole in the hose then it may take in air over night/long periods and take a few turns to start.

hiluxman

it kinda sounds like your starter motor is a bit lazy, its turning the engine a bit to slow

Slidey

hiluxman wrote: »

it kinda sounds like your starter motor is a bit lazy, its turning the engine a bit to slow

That vid is one on youtube he picked as an example I think.

If it is coughing and spluttering once started it may be air in the fuel lines, it might be letting the diesel back overnight.

shamwari

Based on your description of the fault and how car behaves when it eventually starts, I'm wonder do you have an air leak in the fuel system? Can you prime the fuel system before you start it? And when was the fuel filter last changed?

GTE

Slidey wrote: »

That vid is one on youtube he picked as an example I think.

If it is coughing and spluttering once started it may be air in the fuel lines, it might be letting the diesel back overnight.

To clear this up before I have a good read and research of the other replies (including yours):

The first video is an example. Although his start is hugely long due to the temp it sounds similar to mine which lasts about 3 to 5 seconds max(ish).

Also, once the engine does take the idle is perfect. The irregular idle in the vid is not something I have and its only happening in the video as the cylinders wait to heat up as far as I know.

Its really snowing well here now and I am hoping we get some minus temps soon to test the GP system.

Im based on the Meath/Kildare border so if anyone elses TDI's have GP action then maybe I have a further problem with the coolant temp sensor.

PaintDoc, the GP system doesnt seem to need cycling when I turn the key. The GP light goes off right away with the rest of them so that means if the temp sensor is good then its too warm for the plugs or if the sensor is bad the engine thinks it is warmer than it is.



EDIT:

ROW, Slidey and Shamwari:

Ill have a good check of that. It makes good sense alright.

Ill see how I can prime the system and do a test when I can.

Hiluxman:

I think you may have mistaken the video to be mine but the starter motor is certainly a possibility. I know it is dirty because it has stuck in the on position twice in the year and a quarter I have had the car. My god, a year and a quarter already!!

crosshair1

bbk wrote: »

The temp sensor was changed a while back and the guy at VW who diagnosed the battery said that the GP's shouldnt come on until 1 degree or -1degree and I dont think I have hit that yet.

This is incorrect for the AGR engine , and only applies to the later PD's and CRD's in general.

This engine requires heating for temperatures abobe zero and even at 10degs will be hesitant to start without heating.
You need to confirm that there is voltage feed to the plugs for say 10secs or greater in this weather and then you need to confirm that each plug will draw about 10a-15a current with a clamp meter.

With this eliminated you can look elsewhere and at this stage a diagnostic scan would be advisable.

Slidey

To add to that, the mk3 golfs used to put on the heater plugs when you opened the drivers door, I would imagine the MK4 does the same, this will explain why the light goes out so quickly.


I changed the plugs in the sisters TDI octavia and it did make a significant difference on cold starts

GTE

Ill check the GP system so. Ill do some googling.

On the note about the GP's working when you open the door that seems to have died with the Mark 3 but then again that is with the ALH coming onto the scene in the mark 4. The AGR could be from the Mark 3 days. Ill try and sneak in the back door and see what happens

http://www.ehow.com/how_5183612_test-glow-plugs.html
Will that do me for testing the GP's?

Though, even if I get into the car through the front seat and turn the key right away I should see the GP light on for a fair few seconds shouldnt I? I dont wait around when I get in.


EDIT:

Total balls to this now She prefers the really cold!

I just snook up on the unlocked car, opened the door and swooped the key in. I think I noticed the GP light on for a tad bit longer then normal.
Usually it goes out with all the other lights that come on when you turn the key. It stayed on after the other lights but it wasnt on for more then a second extra. The car started pretty fine.

Its teasing me lads!

crosshair1

The mk4 glow plugs are fed from a relay driven by the engine ecu and duration based on the coolant temperature sensor.
Doors opening or closing have no bearing on the control (have had enough of these with parasitic battery drains in the last few months)
I cant even recall a mk3 having this feature maybe some of the early d/tdi's without edc systems and a heater controller relay??
The guide you posted is fine but realistically you dont want to be trying to remove plugs unless you have to, sometimes they break in the head or the tip
is seized and stuck but the body comes out.
Was just smiling when the instructions said turn plug anticlockwise and remove... dont think the author had imagined doing this to some of the older merc diesels!
Also the plugs will stay powered after the glow plug lamp goes out
Test them as per my previous post then you will know that they are serviceable and also that the are being powered up correctly.

GTE

I did not get a chance to check the GP's physically today.
I did get a chance to hook up my freeware VAGCOM and I can report that at a coolant temp of 0 degrees C the engine started fine.

I dont quite know what is different from now and the times it would take longer to start besides it being warmer. If the weather gets slightly warmer it will be interesting to see what happens.

Thanks all.