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mark houghton mark houghton is offline
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Join Date: Jul 2008
Location: Central Washington State
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Originally Posted by tasturbo86 View Post
My 86 turbo will stumble and belch black smoke when I roll into the throttle at about 2500 rpm.
It also runs rich at idle and failed the local smog test.
I pulled the air cleaner and I noticed that the CIS sensor plate 'flutters' at idle.
If I steady the plate with my finger, the idle smooths out.
I have aquired fuel pressure testing equipment, but I haven't gotten around to doing it yet. I'm hoping it is low fuel pressure.
Any ideas?
Your first symptom of belching black smoke when boost begins makes me think you've simply got a leak in the intake...such as a bad o'ring on the intercooler (of which there are three...the bottom and top of the up pipe from the turbo, and where the IC mounts to the throttle body). Spring a leak there, and your metered air will escape, causing a very rich condition.

By all means, check your fuel pressures (system as well as control pressures. Also, check any and all air/vacuum lines attached to the IC as well as the intake manifold.

As to the flutter of the metering plate, I've never watched mine with the air cleaner off so can't say if what you're seeing is normal or not. I believe the fuel accumulator's function - in part - is to dampen the oscillations coming from the fuel pumps and minimize the well as hold accumulted fuel under pressure for easier restarts.
Mark H. 1987 930, GP White, Wevo shifter, Borla exhaust, stock everything else. The result of a massive Pelicanite good will fire recovery effort. Truely an open book, ready for the slippery slopes to modification.
Old 06-15-2011, 11:54 AM
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