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'89 200q with weird boost behavior...
Lately, I've noticed something interesting about my '89 200q's boost
behavior: If I accelerate hard but not quite flat out, it'll peak at 12psi of
boost from 2600 to 4800rpm then fall off to 10psi from 4800 to 6000rpm and
fall off further to about 8psi from 6000rpm to redline. This is with an SJM
AutoTechnic modified ECU and a "Charlie" spring without a shim.
However, if I put my foot *ALL* the way to the floor and hold it there, my
VDO boost gauge will peg at 15psi from 3200 to 6000rpm, which is more than
I'm comfortable running day-to-day. I have checked everything out and so far
as I can tell, there's nothing broken. The diagnostic codes blink 4444 and
all of the sensors and switches test as they should. Still, I don't recall
the car ever behaving this way before. Oh, yeah: I checked the wastegate
diaphragm and it'll hold a vacuum so I ruled that out, too.
That said, the car is running quite well now that I've installed new
injectors and patched the leaking IC again even if it has also begun starting
hard for reasons I've yet to determine. I'm sorting everything out before
installing a new head and turbo and exhaust, etc. so any BTDTs will be
appreciated.
JG
Lately, I've noticed something interesting about my '89 200q's boost
behavior: If I accelerate hard but not quite flat out, it'll peak at 12psi of
boost from 3000 to 5000rpm then fall off to 10psi from 5000 to 6000rpm and
about 8psi beyond that until redline.
However, if I put my foot ALL the way to the floor, it'll peg my VDO boost
gauge at 15psi from 3500 to 6000 rpm, which is more than I'm comfortable
running day-to-day. I've checked everything out and so far as I can tell,
there's nothing broken. Still, I don't recall the car ever behaving this way
before.
Either way, though, the car is running quite well now that I've installed new
injectors and patched the leaking IC again ... it's also running one of Scott
Mockry's modified ECUs, if that makes a difference. I'm trying to sort
everything out before installing the new head/turbo/exhaust, etc. so any
BTDTs will be appreciated.
JG