D24TIC Timing in degrees

[tfb]

I have picked up a 2nd hand diesel timing light. It works by fitting a transducer around the pipe to No.1 injector and the transducer picks up the slight swell/shockwave/whatever as fuel is pumped to the injector.
Now, I can find lots of info on setting the timing on the pump with a dial guage, but none that gives me the timing in degrees BTDC, any one know what it should be?

Regards
TFB

[Paul Clifton]

In theory diesel engine timing reading will be 0deg but in practice is controlled by the injection pump on older systems and ECU 's on the more modern systems and depending on the system can be governed by a number of sensors. Therefore i'm afraid that your 'timing light' will not be much use on a modern diesel as the timing will be whatever the system deems it necessary to be at that time and conditions.

Paul.

[tfb]

ECU??? what's one of those? . The only electrical signal my engine needs(once it's running) is the voltage to hold open the fuel supply valve on the pump!.

There must be a value for the advance when the engine is idling and I can't see why I could not adjust the advance buy rotating the pump while the engine is running and lighting up the timing marks, or am I missing something fundamental?

To me, at least, it seems that setting the timing with a dial guage is akin to setting the static timing on an old petrol engine by twisting the dizzy until the points begin to open. I would have thought a timing light would have been far more accurate as it is on a petrol engine. Then again, if I had a dial indicator and not a timing light I may think the opposite

Regards
TFB

[outnumbered]

Originally Posted by tfb

ECU??? what's one of those? . The only electrical signal my engine needs(once it's running) is the voltage to hold open the fuel supply valve on the pump!.

There must be a value for the advance when the engine is idling and I can't see why I could not adjust the advance buy rotating the pump while the engine is running and lighting up the timing marks, or am I missing something fundamental?

To me, at least, it seems that setting the timing with a dial guage is akin to setting the static timing on an old petrol engine by twisting the dizzy until the points begin to open. I would have thought a timing light would have been far more accurate as it is on a petrol engine. Then again, if I had a dial indicator and not a timing light I may think the opposite

Regards
TFB

lol
mike

[Paul Clifton]

TFB. At the moment I cannot think of any diesel pump that you can adjust with engine running and I have not seen any figures for timing diesels this way.
Common rail diesels are all electronic, ecu controlled with solenoid operated injectors.

Paul.

[outnumbered]

Originally Posted by pc654

TFB. At the moment I cannot think of any diesel pump that you can adjust with engine running and I have not seen any figures for timing diesels this way.
Common rail diesels are all electronic, ecu controlled with solenoid operated injectors.

Paul.

hi paul
i adjust the pump timing with the engine running whilst hooked up to the vol fcr program, this enables me to get it withing the parameters.
mike
850 tdi

[tfb]

Originally Posted by pc654

TFB. At the moment I cannot think of any diesel pump that you can adjust with engine running and I have not seen any figures for timing diesels this way.
Common rail diesels are all electronic, ecu controlled with solenoid operated injectors.

Paul.

Hmm...unsure why you mention Common rail, ecu's etc. as they are not applicable to a D24T. I can see the timing light would not even be able to trigger from a common rail system.

However, the timing must have a static advance of n degrees and the management system (or in my case some spinning weights, I imagine) will alter this value depending upon the conditions and demands placed upon the engine. The static advance is usually very similar to the dynamic advance at idle, perhaps a few degrees difference.

I can't see the base value being 0degrees as this would allow no time for the fuel to burn, which however quick does take a measureable amount of time, before the piston travels downward. As I understand it, the optimum time for ingnition or injection is a few degrees before TDC, so that the fuel is completely burnt/burning at TDC, thus generating the maximum amount of pressure inside the cylinder.

I found some info in an Autodata book that gives the value of 14 degrees @750rpm for n. This does seem quite advanced (I am used to petrol engines at about 6-10 degrees), but if it stops raining tomorrow I'll have go and see what the timing is currently set to and then try advancing/retarding it to 14 degrees and see what difference it makes to the car. It would be nice to get rid of the clouds of smoke I sometimes leave behind me, although it is VERY useful if I am being tailgated on the motorway

I'll try and scribe some lines on the pump housing and bracket before altering anything, just in case it all goes wrong!

Regards
TFB