1986 305 emission question - new thread
silicon212
08-02-2007, 07:04 PM
has anyone ever been able to solve this? Brother in law having same problem with 1986 truck with 305 in it. How do you test emission modules on the quadrajet?
You need a dwell meter and a good manual. The electronic carbs (E4ME, M4ME) require a certain adjustment called the 'M/C solenoid duty cycle adjustment' which also affects something called the 'idle air bleed'. You need to have a good grasp of carburetor fundamentals, you need to adjust the idle mix screws ONCE (during overhaul and at no other time). The screws generally set to 2.5 turns out, you need to follow manual procedures to set the initial adjustments for the lean stop, the rich stop, and the idle air bleed. Once this is done by the book, you install the carb on the engine, start said engine, and hook a dwell meter to the connector in the green plastic tab on the ECM wiring harness (car shown in pic below, truck similar). Set the dwell meter to the 6 cylinder scale and adjust the idle air bleed screw until the meter reads 30 degrees (this is 50% duty cycle) at 1200 RPM. This is going by memory, and there's typically a plate riveted over the idle air bleed adjustment, you will need to drill out the rivets and remove the plate. You can discard the plate, it doesn't need to be put back.
The green tab is shown with a circle around it below.
http://silicon212.org/purge4.jpg
http://silicon212.org/qjetnotes.jpg
You need a dwell meter and a good manual. The electronic carbs (E4ME, M4ME) require a certain adjustment called the 'M/C solenoid duty cycle adjustment' which also affects something called the 'idle air bleed'. You need to have a good grasp of carburetor fundamentals, you need to adjust the idle mix screws ONCE (during overhaul and at no other time). The screws generally set to 2.5 turns out, you need to follow manual procedures to set the initial adjustments for the lean stop, the rich stop, and the idle air bleed. Once this is done by the book, you install the carb on the engine, start said engine, and hook a dwell meter to the connector in the green plastic tab on the ECM wiring harness (car shown in pic below, truck similar). Set the dwell meter to the 6 cylinder scale and adjust the idle air bleed screw until the meter reads 30 degrees (this is 50% duty cycle) at 1200 RPM. This is going by memory, and there's typically a plate riveted over the idle air bleed adjustment, you will need to drill out the rivets and remove the plate. You can discard the plate, it doesn't need to be put back.
The green tab is shown with a circle around it below.
http://silicon212.org/purge4.jpg
http://silicon212.org/qjetnotes.jpg
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