Re: Adjusting fuel mixture

["David Teitelbaum" <jtrealty@xxxx>]

IMHO this procedure assumes too much. There is no way to know if 
everything else is PERFECT except the fuel mixture adjustment and this 
is not a very accurate way to set the mixture screw. The injector 
could be dirty or just a little tight. You really have to put 
the injector in a tester to clean it and check the opening and holding 
pressures. A better way to set the mixture is with a dwell meter 
reading the lambda system. Better yet leave the mixture adjustment 
screw alone, turning it won't "fix" anything. BTW this is a VERY 
sensitive adjustment, 1/8 of a turn can make a BIG change. Just make 
sure there is a good sealing plug in the housing above the screw. A 
plastic golf tee fits nice.
David Teitelbaum
vin 10757



--- In dmcnews@xxxxxxxxxxxxxxx, "content22207" <brobertson@xxxx> 
wrote:
> Fully agree that fuel mixture screw isn't going to turn itself. If
> yours hasn't been touched, look elsewhere for problem.
> 
> BUT
> 
> If you've touched screw and want to put it right again, there's a
> visual procedure known as "cracking" a fuel injector:
> 
> 1) Ensure everything else on engine is tight, properly adjusted, 
etc.
> Make sure you don't have vacuum leak in front of vehicle (cap big 
take
> off on passenger intake rail). MAKE SURE PROBLEM ISN'T WARM UP
> REGULATOR. You only want to do this to put mixture screw back where 
it
> used to be.
> 
> 2) Run engine until warm (driver's formed coolant hose hot --
> thermostat open).
> 
> 3) Stop engine. Pop #3 fuel injector out of head and place in neck 
of
> empty Coke bottle. Use length of 3/4" hose and 1/2 NPT pipe plug (or
> other suitable metal object) to cap #3 injector port. Is little bit 
of
> tight fit over metal lip.
> 
> 4) Restart engine. You'll be able to see injector spray pattern in
> Coke bottle. Adjust fuel mixture screw until pattern just changes 
from
> a stream to a spray (clockwise to richen, counter to lean). This is 
a
> "cracked" injector.
> 
> 5) Leave mixture screw alone in the future.
> 
> Yet another helpful procedure from the Volvo newsgroups (DMC owners
> should hang out there too -- treasure trove of useful info).
> 
> Bill Robertson#5939 (acting more like a Swedish "brick" every day)