The computer monitors the following items: (TBI &
turbo engines have more sensors but are similar in operation)
Oxygen sensor -this is located in the exhaust manifold, it's
how the computer measures air/fuel ratio and what it uses to determine
the fuel curve. It gives out a 0-1 volt signal, where 0 is maximum lean and 1 is maximum rich.
Coolant Temp. Sender -on the side of the "water box" -it tells
the computer the water temperature. It should read between 5000-6000 ohms
between the two pins at room temp.
Vacuum Transducer -on top of the ESA module. This is where the
computer measures engine vacuum and thus determines spark advance.
It's basically like mounting the vacuum advance module on the computer
instead of on the distributor like on older cars. This was replaced with
the MAP sensor on TBI & turbo models.
Hall-effect pickup -inside the distributor cap. The computer
uses this to determine when the spark plugs should fire and is also how
it senses engine RPM.
Carb. Switch -on the end of the idle stop. This lets the
computer know if the engine's at idle or not.
Knock Sensor -Shelby & HO models only. Located on the transmission
side of the intake manifold. Tells the computer when spark knock occurs.
The computer has control over the following:
Negative Coil Terminal -this goes right to the computer and
is how the computer controls spark timing, thus eliminating the old "points"
style system.
Feedback solenoid -on top of the carburetor. It replaces the
traditional "power valve" and is how the computer controls fuel delivery
to achieve optimum air/fuel ratio.
Vacuum Secondary solenoid -on top of the carb. The computer
uses this to bleed out vacuum from the vacuum secondary diaphragm and keep
the secondary throttle plate from opening until the engine has warmed up.
Canister Purge Solenoid -the passenger side of the engine compartment
-when this is energized pressure from the air-pump is injected through
a hose and into the emissions canister. This forces fuel vapors out of
the canister and into the intake.
Solenoid Kicker -on the back of the carb. When engaged the solenoid
presses on the throttle and increases engine idle. Right when the engine
shuts off, the solenoid disengages and backs off of the throttle to prevent
engine after run.
Solenoid Kicker Vac Solenoid -next to the canister purge solenoid.
This is how the computer controls the solenoid kicker. When it's
energized, it ports manifold vacuum to the solenoid kicker on the carb,
and extends it to increase engine idle. When you press the accelerator
and then back off, the solenoid should keep the car at higher then normal
idle for 2 seconds and then let go. It should also turn on whenever the
A/C is activated (on cars so equipped)
Upshift light -Manual trans only. Located on the dashboard.
Lights up at certain RPM/vacuum points. (auto trans models are simply
missing the bulb in the dash)
Radiator fan relay -on the drivers side shock tower. Turns on
the
fan when a specified coolant temp is reached. (some '83 & older cars
use a seperate switch for the fan that is not computer controlled)
Spark advance is determined by three factors:
Coolant temp. -the temperature of engine coolant determines
which vacuum advance schedule the computer will use.
Engine Vacuum -the computer has different vacuum advance schedules
built into it that correspond to different temperatures.
Engine Speed -as the engine increases in RPM so does the spark
advance (similar to the centrifugal advance built in to many
older distributors except it's electronically controlled). Advance
due to speed is disabled when the engine is using the cold advance schedule.
Computer part numbers & applications
There are lots more computers that were used that I don't have info
on.
| Part Number | Year/Applications | Basic Timing | Spark Advance
(16" vacuum applied to transducer, carb switch grounded, 2k RPM) |
| 5213008 | 1980 1.7 a ca | 10 | 17 (w/v transducer connected) |
| 5213012 | 1980 1.7 m ca | 10 | 22 (w/v transducer connected) |
| 5213437 | 1982 | 12 | 55 |
| 5213438 | 1982 1.7 m | 20 | 50 |
| 5213438 | 1983 1.7 m | 20 | 30 |
| 5213480
5213483 |
1982 | 12 | 45 |
| 5213481 | 1982 | 12 | 47 |
| 5213482 | 1982 | 12 | 45 |
| 5213542 | 1982 | 12 | 55 |
| 5213544 | 1982 | 12 | 50 |
| 5213546 | 1982 | 12 | 43 |
| 5213546 | 1982 hi-alt | 12 | 31 |
| 5213641 | 1983 1.7 a | 12 | 23 |
| 5213832 | 1983 2.2 a ca | 10 | 28 |
| 5213834 | 1983 2.2 m ca | 10 | 28 |
| 5213836 | 1983 2.2 a | 10 | 34 |
| 5213838 | 1983 2.2 m | 10 | 31 |
| 5213840 | 1983 2.2 hi-alt a/m | 6 | 34 |
| 5213974 | 1983 2.2 shelby | 15 | ? |
| 5226411 | 1985 1.6 m | 12 | 33 |
| 5226429 | 1985 1.6 can a/m | 12 | 33 |
| 5226433 | '85 2.2 hi-alt a | 10 | 41 |
| 5226439 | '85 2.2 hi-alt m | 10 | 42 |
| 5226449 | '85 2.2 shelby | 15 | 38 |
| 5226451 | '85 2.2 a ca | 10 | 37 |
| 5226455 | '85 2.2 m ca | 10 | 42 |
| 5226505 | '85 2.2 can a/m | 10 | 41 |
| 5226507 | '85 2.2 can a/m | 10 | 41 |
| 5226645 | '85 2.2 ca shelby | 15 | 36 |
| 5227608 | '87 2.2 can a | ? | 29 |
These are the carbureted computer's pin-outs for 1985-7 computers. (1984
& eariler computers have different pin-outs)
The 10-pin connector
1 to negative ignition coil terminal
2 12VDC (in from ignition switch)
3 12VDC (out to hall effect pickup)
4 not used
5 hall effect pickup
6 knock sensor input (HO engines)
7 carb switch
8 to radiator fan relay
9 ground
10 ground
The 14-pin connector
1 vac. secondary solenoid
2 temp sender
3 oxygen sensor input
4 temp sender
5 mixture solenoid control
6 purge solenoid
7 to diag. connector
8 12VDC
9 purge solenoid
10 12VDC
11 tachometer output
12 upshift light
13 distance sensor input (if equipped w/cruise control)
14 to diag. connector