Fuel & Ignition - Systems Changes
90buick11 Bulletin 89-6E-32Date Nov. '90
Ref. No. 89-293-6E
Corp.Ref.No. 976106
SUBJECT: 1988-89 2.3L QUAD 4 ENGINE IGNITION AND FUEL SYSTEMS DIFFERENCES
MODELS AFFECTED: 1988-89 SKYLARK WITH 2.3 QUAD 4 (VIN D)
The ignition modules on a 1988 and 1989 2.3L Quad 4 engine are not interchangeable.
In 1989, a 15 degree advance crankshaft is used on a 2.3L vs. a 0 degree advance crankshaft on 1988 2.3L engine. This required different module timing to be compatible with the initial timing advance of the crankshaft reluctor wheel. The timing advance enhances cold startability and emission.
A 1X reference signal was also added in 1989 for better fuel control and emissions. This signal is used to fire the paired injectors in the correct sequence. This is called ASDF Fuel Injection which is described in section 6E3-C2 of the 1989 service manual.
Two different methods of fuel injection are used on the 2.3L Quad 4 engine.
In 1988, all 4 injectors are pulsed simultaneously, delivering half the necessary fuel for combustion at each revolution.
In 1989, a pair of injectors are fired every 180 degrees of rotation. Injectors 1, 4 and 2, 3 are paired and pulsed twice, once on compression and once on exhaust stroke for each cylinder.