Jeff (Witzer):
Unlike other writers, I’m not so sure that the problem lies at the feet
of your local Mazda dealer. I noted at the bottom of your post "Pettit
Turn Key Terror". Most modifications mean that you’re the one
reponsible for changes in the functioning of the car’s systems. The
dealer’s techs only have the diagnostics made available by the
manufacturer: you’ll have the be the expert in any case! If you treat
the techs with consideration and respect, they’ll usually be very
helpful, at least if our experience is any indicator.
Your symptoms indicate possible trouble in two areas of the engine’s
functions which possibly affects a third. Either you have a wastegate
problem, a vacuum leak and/or the engine’s computer is affected. The
engine’s output seems to be affected at its greatest load. The
wastegate is a straightforward device and under certain conditions it
seems to be performing as expected. (We’re assuming that the guage is
giving you an accurate reading, but your experience seems to confirm
that it is.)
I’m wondering, therefore, if you still have a vacuum leak that’s
undetected by checking the hoses. If it’s been removed and "blue goo"
was used to replace it, then a gasket was used, you may have a problem.
I’d begin by carefulling checking all gaskets and mating surfaces, using
a vacuum gauge to test them, then road test the car with the gauge in
place. If you feel these areas check out OK, it’s wise to fit an
exhaust temperature gauge, a pyrometer, to note whether the engine is
running in a lean state under certain conditions. Running lean under
certain conditions will affect the computer, wastegate, fuel flow, etc.
If you’ve modified the car, also check back through the modifications to
possibly pinpoint the problem.
Mike Allen (gt3…@winternet.com)
Doug Sherwood