Poor starting... AFN 1998 A4

[Nigella]

Following a trip to the local garage to try and locate the source of a fuel leak around the IP, (separate thread) The car is now very difficult to start.


Is there a bolt/screw that the garage could have tightened on the outside of the IP, in error in an attempt to stop the leak but somehow have affected the starting of the engine?


I was thinking more on the lines of a poor connection on the glow plugs or a break in the GP loom as a result of the wire being moved out of the way to get to the IP.


I dont have VAGCOM yet so any reasonable suggestions welcome.

[Crasher]

They may have moved the pump on its mountings which alters the Commencement Of Injection.

[Nigella]

I was watching them and didn't see any movement at all.

They were only tightening the bolts, fuel hose unions etc and if I remember correctly, only one of the rear pump housing bolts was a little loose and maybe one 12 or 13mm bolt in the centre rear which I think did turn slightly.

[PaulF2.5TDi]

AS crasher said, the timing may have been altered.

You need somebody to check the pump timing with VCDS once it is hot.

[Nigella]

How can the timing have been altered??

Are there adjustments that can be made on the back of the unit by what appears to be tightening two case securing nuts/bolts??


What is the function of the tri sided nut/bolt on thr side of the pump between the hp injector pipes??



Thanks.. N..

[Crasher]

Seriously. before anything else, get the codes read to make sure nothing is stored and with the engine hot (over 85°C) have the Commencement Of Injection checked preferably using the extremely useful VCDS timing graph function but if another system is all that is available, follow this chart in Basic Settings 04 and observe the values in blocks 2 (A) and 9 (B) of group 000. if you took this problem to another garage who knew what they were doing, this is the very first step they would take. I will not accept the specification as being OK in range C, I aim for the central dotted line, nothing else will do....



Select Engine Basic settings Group 04
Select Display Group 000
Observe the value in display zone 7 (coolant temperature).
Specified value: Must be less than 73 which corresponds to 85 °C
Do not continue with the test until the coolant has reached the specified temperature.
The commencement of injection in display zone 2 depends on the fuel temperature value in display zone 9.
Specified value: Range C in illustration
A - Display zone 2 Commencement of injection
B - Display zone 9 Fuel temperature
Notes:
If injection start is within specified range C when tested, no adjustment is required. If the commencement of injection (timing) is outside the specification tolerances, adjust the commencement of injection as follows:
Loosen the injection pump securing bolts by approx. one turn, leaving the easiest bolt to reach till last.
By hand, hold the injection pump under tension in the direction to be adjusted.
If the commencement of injection is advanced, turn the injection pump in the engine's direction of rotation, if the commencement of injection is retarded, turn against the direction of rotation.
Carefully loosen the last securing bolt until the pump can be turned slightly and then retighten the securing bolt.
Observe the value in display zone 2 and, if necessary, repeat adjustment until the value displayed remains at the mean value for the specified range -C-
Tighten the injection pump securing bolts to 25 Nm.
Check the commencement of injection again.
Note:
After a dynamic adjustment of the injection pump, the injection lines on the injection pump must always be loosened and then tightened again (25 Nm). This relieves the strain on the pipes and prevents vibration fractures.