This is how you test your air flow meter

[syncrosimon]

The guru 10cent on the samba has made this video which explains how you can test your air flow meter for digifant or digijet DJ MV SS etc fuel injected engines. So simple.

http://s105.photobucket.com/albums/m218 ... V02923.flv" onclick="window.open(this.href);return false;

Simon.

What he has done is just peel back the rubber boot, leaving the wiring in place and with the ignition on the ecu supplies the afm with 5 volt, the return voltage which is read by the ecu is then just read on a volt meter for a smooth increase from idle.

The topic is here.
http://www.thesamba.com/vw/forum/viewtopic.php?t=369815" onclick="window.open(this.href);return false;

[syncrosimon]

Done my own test now, sad I know...

http://www.youtube.com/watch?v=6Tn8dyzn9a4" onclick="window.open(this.href);return false;

[wasserleaker]

Going to be altering the spring pressure in my AFM one notch at a time and doing test runs, plug colour checks at different spring tension settings over the weekend, in an attempt to richen the mixture slightly on my 2.1 DJ engine, which has been running very lean since fitting a VW Speedshop straight thru stainless exhaust, which has loads less back pressure than the standard xhaust, the overrun popping I had has pretty much gone after getting the timing spot on, but plug insulator nose colours are still very white.

[syncrosimon]

Here is a diagram of how to adjust the mixture on the DJ, MV etc. This method alters full throttle and general driving mixture, where as the screw adjustment only caters for the tick over.



Adjustment is simply a matter is undoing the wiper screw and rotating the
wiper slightly. The only hard part is keeping the wiper from moving while you
retighten the screw. This is less of a problem if you can't detect small
changes in the mixture. When you are done, drop some silicone or a drop of
purple loctite where the screw meets the slot underneath.
Before adjustment center the bypass screw so you have more adjustment
options later. Maybe 1/4 open would be better as these engine tend to run
rich.
You can also adjust the gear under the wiper but only if your mixture is way
way way off but it's a last resort adjustment.

By doing this adjustment you are moving the wiper arm on the current track, and thereby weakening or en richening the mixture, by either increasing the voltage to the ecu or reducing it.

This could be done very easily on a rolling road with a real time mixture reading, or by wasserleakers method of looking at the plugs, or by fitting a lambda probe and having a dash gauge telling you where your engine is at.

This gauge available from demontweeks.



DJ's are high compression engines and keeping them spot on for mixture is very important. The MV has the advantage of having the mixture corrected by a lambda probe, but running at a lower compression is slightly down on power.

Note that on an MV the lambda will sort out most problems, but tuning the engine can alter the engines requirements beyond that which the ecu can alter the mixture. A basic setting then without the lambda connected can be made using the above technique, putting the engine back to where it can tune it's self.