[urq] Reality Check (Dyno results) Follow up (long)
urq at moregraphics.nl
Wed Mar 31 09:28:46 EST 2004
Hi, thanks everyone for their input.
I ran the IM test and there is 100% NO vacuum leak. I also checked vacuum on
the waste gate diaphragm and it holds 10² Hg forever.
I connected the gauge (Mityvac) to the IM vacuum port and run the engine at
idle, according the Mityvac manual it should read a steady 16-22² Hg with a
Mine does 15-16² Hg when cold and later 16-17² Hg. NOTE: the needle
fluctuated very rapidly in the range of 1² all the time at idle. The manual
says it should be steady and does not mention such small movement, all it
does say is:
³Worn valve guides OTOH, upset the air/fuel mixture and the gauge reading
will be lower then normal and fluctuates rapidly in a range of 3². As the
speed of the engine increases, the needle will steady.²
My readings are 1² and yes, steady when increasing rpm, could this indicate
premature¹ wear of the valve guides?
But the manual also says: ³ Floating motion indicates (carburetor) too rich
or too lean.² I know my engine is running a tad rich, could this explain the
Also, the manual says a low reading of vacuum pointer indicates late
ignition timing OR intake manifold air leak. In case of any leaks, the
needle will be about 3² to 9² Hg below normal but will remain steady, which
it does, but I¹ve checked the vacuum, and regarding timing, my ECU is of the
correct version (the Euro GV ECU uses a different map i.e. earlier than the
About 6 months ago the compression of all cylinders was 6.7 ~ 6.9 Bar. I
don¹t think it¹s changed much since, because it pulls better now then 6
months ago... Are these reading ok?
All this makes me wonder if the GV really has 200 BHP? The previous owner
blew up his engine once (broken oil cooler lines) back in 88 and Audi ...
Program rebuilded the complete engine, incl. new head, turbo, wastegate etc.
Perhaps the previous owner got scared and ordered to cut¹ the power by
decreasing the pressure of the WG spring. Fact is, the current boost
pressure is only 0.45 bar (absolute) and should be 0.8 bar if I¹m correct.
Last but not least: could the turbo loose 25% of power by age? I know it
doesn¹t smoke or has excessive play, the propellor blades are still in one
piece (checked). All it does is wistle quit heavily, maybe the air filter is
blocked? I¹m not using the original paper filter but the PiperCross OEM.
Could I accidentely reversed this filter and now blocking air? If it¹s
dirty, could this dirt¹ cut 25% of BHP?
Questions, questions and even more questions. I would like to thank you for
reading this, perhaps you could add some thoughts... Thanks.
'86 quattro GV (WR)
'85 coupe KV
'82 coupe DD
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