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Cheap multimeter & adjusting mixture

Hi List!

For anyone
a) living in Europe
b) looking for cheap automotive multimeter
you may want to check if there's a shop of the Swedish automotive
supermarket net Micro in your vinicity. I've just bought a multimeter
there: the specs are
- DC voltage up to 1000V
- current up to 10A
- resistance with audible continuity check
- rpm and dwell for 3,4,5(!),6 and 8 cylinder engines
And the price is - tadaaa! - under 30 bucks. 
Not being quite able to believe that something worth under 30 bucks can
work, immediately after arriving at the garage I began to measure
frequency valve duty cycle - that's what I bought this meter for. Set
for 4 cylinders the dwell oscillated between 28 and 37 degrees, which
(as I understand) means 33/90 = about 37% duty cycle. With the dipstick
removed the average dwell was about 45 degrees, which equals to 50% duty
cycle. Because the duty cycle increased as I removed the dipstick, I
assume I was measuring the "true", not "reversed" duty cycle - the more
the frequency valve works, the richer the mixture is, right? So with the
37% duty cycle with the dipstick installed, I'm running too lean. Of
course, every now and then I _have_ to reveal my stupidity, so in search
for the mixture adjustment screw I figured out (don't know how, don't
ask, I was hungry and tired) that I have to remove the yellow plug at
the intake boot. After getting yet more tired, bitching about how
stupidly German cars are build, almost tearing the whole injection assy
out of the car, breaking the plug and extracting the remains with
various tools, I figured out I removed and destroyed an innocent plug
that wasn't meant to be removed. I substituted the plug with a bolt
wrapped with electrical tape, praising the Lord I didn't break anything
expensive. I finally found the adjustment screw (or I think I have), so
I probably will attempt to adjust the mixture and idle speed. I would be
grateful for any hints - my previous post on this subject didn't catch
much attention... :-( My idle and WOT switches do work and the temp
sensor is within spec, yet the cars idles at 1100rpm when hot. What's

Aleksander Mierzwa
Warsaw, Poland
87 Audi 5000CS turbo (mine)
88 Renault Medallion wagon (mom's)
91 mountain bike (just in case both cars broke at the same time :-)