VWDiesel.net The IDI, TDI, and mTDI source.

Engine Specific Info and Questions => IDI Engine => Topic started by: overdrivegear on November 16, 2007, 01:29:26 pm

Title: Pump timing advancement: How To?
Post by: overdrivegear on November 16, 2007, 01:29:26 pm

Background:  I have a very rough idle and tons of white smoke produced to unburned fuel.  Brand new injectors didn't help the problem.  Did a leak down test:  all cylinders retain 95% with excellent valve sealing.  In other words, compression is superb.

I'm thinking the timing on the pump is slightly retarded.  I timed it before using the proper procedure and tools (so it wasn't eye-balled) and set the timing right in the middle of the specified range.

How exactly do I advance the pump and how much (since this is a 'feel' type of thing)?

Title: Pump timing advancement: How To?
Post by: Vincent Waldon on November 16, 2007, 02:21:51 pm

What setting is the timing at now ??

Title: Pump timing advancement: How To?
Post by: overdrivegear on November 16, 2007, 06:30:16 pm

The Haynes manual called for a setting of '0.83mm'.  That's what it was originally set at...and it sucked.

This time I went back and set it to 1.00mm (0.0393 in) and it runs very well now!  The power is there and the emissions at operating temperature is almost nil.  Do I need to go even further and bounce the lift up to 1.05 mm (0.0414 in)?

Title: Pump timing advancement: How To?
Post by: Vincent Waldon on November 16, 2007, 06:35:43 pm

Common wisdom seems to be that 1.00mm is about the best for an non-turbo car... 1.05mm for a turbo.

If you're happy with the performance, emissions, etc, now I'd be included to leave it.


Vince