Quote:
Originally Posted by ChevyTech
The light is coming on because of the IAC trouble code.
The IAC position is at zero in your data and the engine is above the desired RPM.
Either the IAC or its wiring has failed so it will not close when sent pulses by the computer or the engine has a vacuum leak.
A common vacuum leak on these trucks is the gasket that is right under TBI unit.
You can look down the passenger rear corner of the TBI unit and see the IAC plunger to see if it looks like it has a the passage closed. If the IAC is truly fully extended and has the passage fully closed off and the engine is running at 700 RPM then there is a vacuum leak somewhere.
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ok i checked for a possible internal manifold leak while engine was running i removed oil cap no suction , good sign ..
the code 44 lean mixture reading would be from? i checked asdl again and the o2 sensor is fluctuating voltage which tells me its operating ok.
i did notice when ignition was to the on position the IAC read a reading steady voltage , then when truck fired up it reads 0 no voltage fluctuation ,tells me its non functioning.
can the IAC be removed and tip cleaned with carb cleaner?
and spray inside tbi housing for it?, if this fails a new IAC could be the fix.
whats the procedure for vac lines outside can u use carb cleaner along lines?
if engine rpms alter that's where the leak is? correct?
is it safe to use while engine is cool?
any other alternative to vac check lines?