For 96 all Chevrolet engines are Sequential Port and are equipped
with On Board Dianostics Phase II (OBDII) PCM's. Sequential Central Port Injection
is a standard on the 4.3L/4300, 5.0L/5000 L30, 5.7L/5700L31, and 7.4L/7400 L29
engines. What's nice about all this ?,...They will fit the old engines, but
heads would also have to be changed on the 4300, 5000 and 5700 engines.
Retrofit kits are available from FIS. For Example, Sequential
Tuned Port Injection or Sequential Central Port, both systems are available
from FIS.
Other Technological mods include Cam Sensor / Crank Pos Sensors
in lieu of distributors. EEPROM Computers, Vortec Heads, Mass Air Flow Sensor,
Roller Cams / Roller hydraulic lifters come with all engines. Retrofit kits
are now available, from FIS, for Sequential Port Injection which will fit
the SB, BB and the 90 degree V6 GM Engines.
Electronic Control Module(ECM)
The ECM's provided with the original equipment MPFI systems
are indicated below:
ECM
Y=Corvette F=Camaro ,Firebird, Trans-AM CK=GMC, CHEV trks
Model Year GMpartNo Engine
F,Y 1985 1226870 5.0L/5.7L
F,Y 1986-1989 1227165 5.0L/5.7L
F 1990-1992 1227730 5.0L/5.7L
Y 1990-1991 1227727 5.7L
Y 1992 16159278 5.7L LT1
F 1993 16159278 5.7L LT1
Powertrain Control Module (PCM)
The PCM is a programmable computer and does not contain a
EPROM or calibrator as did its predecessor. The PCM contains a Electronically
Eraseable Programmable Read Only Memory (EEPROM). This unit must be programed
before being placed in service. These Units can be re- programed for any engine
/ transmission combination. All of these units are Sequential Port Fuel Injection
(SEFI).
PCM
Model Year GMpartNo Engine
BF 1994-1995 16188051 5.7L LT1
Y 1994-1995 16181333 5.7L LT1/LT4
F,Y 1996 16214399 5.7L LT1
F 1997 16242921 5.7L LT1
F,Y 1997-1998 16238212 5.7L LS1
CK 1996-1997 16229684 4.3L,5.0L,5.7L,7.4L
16216568
16244210
CK 1998-1999 9359699 4.3L,5.0L,5.7L,7.4L
16250279
16258835
While each of these ECM's/PCM's will provide excellent performance
for the Port and TPI systems, they are not interchangeable. That is a 1227165
will not plug in to a 1226870 harness and operate. The wiring for these systems
are not interchangeable, without modifying the wiring harness. The LT1 PCM is
not compatible with the earlier ECM's due to significant changes in the distributors
of these engines.
The CK truck engines use a crank shaft sensor and camshaft
position sensor to provide timing information to the engine.
CALIBRATORS
The calibrator is a Programmable Read Only Memory (PROM) Chip
which is installed in the ECM. It is this device that provides specific information
for the ECM and allows for different timing characteristics,and injector pulse
width for the 5.0L / 5.7L engines. A Calpak, a separate chip on the Calibrator
Modules, normally provides the information to the ECM for rear axle gear ratio
on pre 90 models. Information for the vehicle Anti Theft system, auto / manual
transmission, and emission control system, typically resides in the EPROM. To
allow for the various Engines, transmission, gear ratio combinations and to
meet national, international and state standards for emissions,a wide variety
of these Calibrators are available from GM. After 1987 some calibrators incorporate
a vehicle anti theft system (VATS). The ECM will not fire the injectors until
it receives the proper signal from the VATS module. The 1985 TPI calibration
is contained in a EPROM (Eraseable Programmable Read Only Memory) and is a 32K
chip. The 1986-89 ECM contains a 128K EPROM, 90-92 ECM's use a 256K EPROM. The
94 Plus EEPROM is even larger. The factory ECM/PCM has a Learning capability
which allows it to make corrections for minor variations in the fuel system
to improve performance and driveability. There are two learning features. The
Integrator and Block Learn (I and BL) and Block Learn Memory (BLM) cell. The
I and BL feature is normal with a value of around 128. If this value is higher
than 128, it indicates that the ECM is adding fuel to the base fuel calculation
because the system is running lean, a value lower than 128 indicates that the
ECM is taking out fuel because the system is running rich. The integrator is
a short term corrective action while the BLM is along term correction. The BLM
value will change if the integrator has seen a condition which lasts for a longer
period of time. There are from two to sixteen different cells which the ECM
modifies, dependingon RPM, airflow or manifold air pressure and other conditions
suchas AC "ON" or "OFF", etc. The ECM learns how much adjustment is required
in each cell, retains it in memory, and applies these adjustments when the engine
operates in that cell or RPM - Load Range. These features of the OEM ECM allows
the system to adjust itself AUTOMATICALLY to your engine and assure peak performance
for stock and other than stock engines. When the vehicle power is disconnected
for repair or to clear diagnostic codes, the learning process has to begin all
over again. To TEACH the ECM, drive the vehicle at operating temperature with
moderate acceleration and idle conditions. Performance Calibrations typically
change the parameters for fuel flow, fuel cut-off and spark advance-timing and
will allow increased fuel flow and modify the spark advance curves during rapid
acceleration.
WHAT THE ECM - PCM DOES: The 1985-1988 TPI system utilizes
the following sensors and devices to control the engine: Mass Air Flow Sensor,
Manifold Air Temperature, Coolant Temperature, Oxygen Sensor, Throttle Position
Sensor, Cold Start Switch, Cold Start Injector Fuel Injectors, Idle Air Control
Valve, Distributor Electric Spark Timing, (Module in distributor TPI) Electric
Spark Control, Module and Knock Sensor.
When the starter is engaged and the coolant temperature is
less than 100 deg F. The cold start injector provides a spray of fuel, of 8
seconds duration max, to each cylinder via a air distribution system built into
the intake manifold. If the engine temperature is greater than 100 deg F, the
cold start injector is disabled by the cold start switch. Upon startup the ECM
utilizes information in the calibrator to establish the initial pulse rate for
the injectors and the engine starts. At this time the engine is operating in
open loop mode and will continue to do so until the engine warms up. After the
warm up period the ECM scans the sensors, if all sensors are operating and within
their proper range, the engine then goes into closed loop operation. This means
that the sensors are dynamically controlling the engine. In the event the information
received is higher or lower than the normal range, a code will set in the ECM,
and the Check Engine or Service Engine Soon light will come "on". The ECM receives
information on air flow, engine temperature, air temperature, exhaust gas oxygen
content and throttle position. This information is used to calculate the proper
pulse width for the injectors and fires the injectors for the calculated period.
This procedure is repeated continuously in very rapid sequence to maintain the
optimum fuel air ratio. The electronic spark control components provide maximum
advance, if engine knock is detected the spark is automatically retarded. This
too, is a continuous process. It should be noted that the following components
are MATCHED for optimum performance; Distributor - EST module, ESC module, knock
sensor and ECM calibrator. These components are not interchangeable between
5.0L - 5.7L engines. 5.7L components referenced are recommended for 327 - 400
CID engines. 5.0L components are recommended for 265- 305 CID engines.
In 1989 the cold start injector was deleted. The calibrator
provides a wider pulse width on startup to provide a richer mixture for a cold
engine. All other features are the same. In 1990 the MAF was replaced with the
MAP sensor, in 94 the MAF returned with a MAP sensor. The1990-92 TPI system
still operates the same except that Manifold AirPressure is used to calculate
injector pulse width as opposed to airflow. The 1990-94 TPI - LT1 system also
uses a more sophisticated VATS system to disable the injectors. A resistor is
embedded in the ignition key. The resistance is read by a VATS module (Camaro,
Firebird and Trans AM) or a Command Control Module (CCM) for the corvette. If
the key is the right resistance a signal is sent to the ECM enabling the injector
circuit. If the sequence or the resistance is not correct,the engine will not
start.
The PCM introduced in the 1994 Corvette, Camaro and Firebirds
for the LT1 engine accomplishes the same functions as the earlier modelsin much
the same way, but there are some significant differences. The 94 and up LT1
is a sequential port fuel injection system. The injectors are fired in coordination
with the opening of the intake valve. The distributor and electrical spark timing
system, now referred to as "Opti-Spark Control", has an optical sensor which
counts light pulses through a perforated disc in the distributor. There is NO
timing adjustment for the LT1. The Mass Air flow sensor is back in 94 and is
one of the primary sensors for fuel control. The MAP sensor is a backup for
the mass air flow sensor. All other sensors are the same except that the TPS
is no longer adjustable. The only adjustment is idle control, and this too is
factory set.
The 96 OBDII engines all use EEPROM computers making Chip
technology something from the past. These PCM's and VCM's have the ability to
determine a cylinder misfire and will even tell you which cylinder midfired.
Opti-Spark is now the standard ignition system on 5.7L LT1-LT4 engines. For
96 a combination crankshaft position sensor and cam shaft position sensor perform
the timing functions on all the 4.3L, 5.0L 5.7L and the 7.4L engines.
The LS1 is now the new small block appearing in the Corvette
in 97 and the Camaro / Firebird in 98. The LS1 does not have a distributor.
The PCM uses the information from the crank and camshaft position sensors
to calculate timing and fires the individual ignition coils.
One thing is CLEAR, Innovation is alive at GM.
CASTINGS
The 1985-86 intake manifolds will fit the older small block
heads without modification. In 1987 and up, the heads were designed with vertical
bolt taps for the two center bolts on both sides of the intake manifold. With
a little drilling the newer manifolds will fit the older style heads. The intake
manifolds are therefore interchangeable for all small engines. The plenum is
interchangeable for all model years thru 1990. The 1990 and up have tapped holes
for the mounting of a MAP sensor (right rear of plenum). The throttle body is
different on 90 and later models, modifications can be made to the plenum to
use the 90+ Throttle Body by drillling a hole in the front of the plenum. Intake
tubes (runners) are interchangeable for all model years, however the left intake
tube through 1988 has a mounting for the cold start injector, for 89 and up
this mounting is deleted.
NOTE: Throttlebodies 85-88 are the same and must be matched
to plenums 85-88. To work properly on 90 and up plenums a hole (1/2") must
be drilled, between the intake openings where the throttle body mounts, to
allow for passage of idle air from the IACV to the plenum. 89 and up throttlebodies
will work on earlier plenums without modifications.
LT1 Throttlebodies
The 93 Throttlebody on the LT1 engine is similar to the TPI,
but does not have an EGR port. The throttle linkage lever is also slightly
diffetent. The 93 throttlebody does have a stud for the trans TVS cable. The
94 and up units do not. If you are using a 700R4 / Turbo 350 transmission,
a stud will have to be mounted for the TVS cable.
FUEL RAILS
Stamped - F=Camaro, Pontiac Y=Corvette
Number 5.0L 5.7L Bosch Lucas Multec Rochester Veh Year
17085052 X X F 85-87
17087264 X X F 87-88
17089024 X X F 89
17080100 X X F 90-91
17085050 X X Y 85
17085019 X X FY 86-87
17086106 X X FY 86-87
17087265 X X FY 87-88
17087266 X X FY 87
17088065 X X FY 88
17089025 X X FY 89
17089026 X X FY 89
17090101 X X FY 90-(92F)
17090102 X X FY 90-(92F)
17094083 X X FY 93-96 LT1
17095152 X X Y 96 LT4
TPI Fuel Rails
The TPI fuel rails have a few differences. If the left side fuel rail has a
fitting at the end close to the firewall it is from a 1985-88system. The
fitting is for connection of the cold start injector fuel line. The left
side fuel rail is stamped at the factory to identify same with the engine.
The Fuel Rail Identification Table above will assist you in identifying
your system as a 5.0L / 5.7L and the injectors furnished with those
systems.
LT1 / LT4 fuel rails
The 93 Fuel rails do not have a crossover tube at the front
of the intake, nor does the intake have provisions for the crossover. The
crossover setup is on all 94-97 LT1 engines. The fuel supply and return lines
are on the left side of Camaro, Caprice, Cadillac and Buick engines. The Corvette
has both the fuel lines on the right hand side.
LS1 Fuel rails
The 97 LS1 has provisions for a supply and return line. The
98 and up fuel rails have a supply line only. The fuel system of the 98 LS1
has a regulator built in to the fuel pump return assembly the return line
is from a "T" fitting between the fuel filter and the engine.
Distributors
All 85-86 systems used a GM HEI distributor. The connector
for the distributor is keyed differently than previous model years. 87-92Camaro
and +Pontiac systems use a small diameter distributor with an external coil.
87-91 Corvette's still use the HEI distributor. Either distributor will work,
however the connectors are different. FIS can furnish adaptors -connectors for
either application. The HEI Distributor for the 85-86 5.0L engine has the number
1103679 stampedin the aluminum casting at the base of the distributor. The 85-91
5.7L HEI unit is stamped 1103680. The smaller diameter (72mm) distributor is
stamped 1103479 on the metal plate beneath the distributor. The72mm Distributor
was furnished with 5.0L/5.7L engines on the Camaro,and Pontiac engines 87-92.
As mentioned earlier the LT1/LT4 has an optical sensor and
is significantly different than the HEI system. Distributors are not interchangeable
for these different engines.
Fuel Pumps
The OEM fuel pump for TPI/LT1 is an "in tank" fuel pump with
an operating rating of 50 PSI and 24 GPH. This pump is recommended for all vehicles
with in-tank pump mountings. We also offer a chassis mounted fuelpump which
has an operating rating of 60 PSI and 30 GPH. This pump is also an AC DELCO
unit. It is important to note that Throttle Body Injection systems operate at
12 PSI. Almost all carbureted systems operate at low pressure utilizing a mechanical
pump. An electric pump is definitely required as referenced above for all Port
Injection systems. A return line is required to the fuel tank. A 3/8 or 5/16inch
supply line is required. 3/8 is recommended. 5/16 inch is recommended for the
return line. The fuel tank must be vented so as not to buildup pressure. Recommended
location for the fuel pump is close to the fuel tank.
Fuel Injectors
There are a number of Fuel Injectors on the market today the
following injectors have been furnished on GM OEM systems: Lucas, Bosch, Rochestor
and Multec. The prices vary considerably and performance differences are hard
to detect. Basically they are sized for application. The 5.0L injector is sized
to deliver approximately 4.05 milligrams of fuel with a 2.5 millisecond pulse
or 18.13 lbs per hr at approximately 36 PSI. The 57L injector is sized to deliver
approximately 4.83 milligrams of fuel with a 2.5 millisecond pulse or 23.92
lbs per hr at approximately 43.5 PSI. This information is typical for all manufacturers
and flow rates will vary slightly even between identicle injectors.
Lucas is presently pushing their new High Output Disc Injector
and is referred to as a High Performance Injector. This product was introduced
in March of 9l. They are competitively priced at approx $60.00 each. A wide
variety of flow rates are available to include 18lb/hr, 24lb/hr,28lb/hr, 37
lb/hr. These are all 16.2 Ohms and will work well with all GM TPI ECM's Rochestor
injectors are presently furnished for the 90-94 GM 5.7L engine. It has an all
metal nozzle and performs well. Priced at approx $75.00 each. Bosch injectors
are also an excellent choice at approx $87.00 each.
While there are significant differences between the TPI and
LT1 induction systems and computers, the injectors are essentially the same.
Sequentialport injectors and batch fired injectors are sized in the same manner.
We regret that we have not been able to make DYNO comparisons of these products.
We will be glad to share whatever we hear on this subject with you when you
call. FIS stocks all of the injectors referenced.
Wiring Harnesses
The 1985 Engine Harness for all vehicles incorporates a MAFS
module which plugs into the harness in the vicinity of the ECM. If you are purchasing
a system thru a salvage yard, be sure to secure this component which mounts
piggy back on the ECM. A single relay and the ESC module are mounted on a common
bracket in the engine compartment. The relay is the fuel pump relay.
The 1986-89 Harness has three relays and the ESC module mounted
in the engine compartment. The 89 harness does not incorporate connectorsfor
the cold start system. Please note that a mass air flow sensoris required on
all systems thru l989. Please note that while the connectors for the 85 ECM
and the 86-89 ECM are the same, they are NOT interchangeable.The ECM's are different.
The 90-92 systems are considerably different than their predecessors.
The 90-92 systems use a Manifold Air Pressure (MAP) sensor in lieu of the Mass
Air Flow Sensor. This system is referred to as a Speed Density System. The Electric
Spark Control (ESC) module is also incorporated in the ECM. All hardware components
remain the same ie., intake runners, fuel rails, throttle body, distri butor
and intake manifold. The EST module, in the distributor and knock sensors are
different than the earlier models and must be matched. All hardware components
are interchangeable with earlier models.
While the 90-92 systems are cheaper to manufacture, it is
questionable as to whether Speed density is better than the Mass Air Flow System,
especially when GM brought the MAF back in the 94 LT1. But who are we to question
GM engineering. All systems appear to perform very well indeed. The 90-94 system
has a single relay for the fuel pump mounted in the engine compartment. There
is no ESC module as previously discussed. These functions are performed by a
module in the ECM/PCM. The ECM's for the 90- 92 Camaro and Pontiac are different
than the 90/91 Corvette.
The Pontiac and Camaro use a 1227730 ECM and the Corvette
uses a 1227727 ECM. The difference between the two is in the ECM enclosure and
ECM connectors. The Corvette enclosure is built for mounting in the engine compartment.
Camaro/ Pontiac are built for mounting in the passenger compartment. Internally
they are the same. Calibrators are interchangeable. It should also be noted
that the Assembly Line Diagnostic Link (ALDL) connector ISNOT normally part
of the Factory Engine Harness. It is normally part of the instrument panel harness.
The factory engine harness also includes a number of connectors which are not
required for "Off Road Use". These connectors are Air Management, Transmission,
EGR, Electric Fan, Instrument Panel Oil Pressure Sender, Water Temperature sender,
AC High Pressure Switch, VSS and VATS module to mention a few.
From 94 and up its the PCM and no calibrators. The PCM for
the LT1 is the same in the Corvette, Camaro, Firebird, Buick and Caprice. This
unit is Programmable as previously discussed. These units are completely different
than their predecessors. FIS can program these units for any LT1/engine transmission
combination. Performance and special calibrations are also available.
In 96 OBDII computers were introduced. These computers require
a full compliment of emissions equipment, ie., 4 O2 sensors, EGR control and
air pumps on passenger car engines. The LT1 engines 96 and up will work with
94 electronics and can be st up for 'Off Road' applications. The Vortec V8'
can also be retro-fitted with earlier electronics for "off road" applications.
The LS1, however requires a full compliment of emissions equipment. The 98
GM trucks incorporate a "Passlock" system that is similar to the earlier "Passkey"
system found in passenger cars (Vehicle Anti Theft System). It is easier to
use a 96-97 computer than it is to try and run the 98 computer with a passlock
system.
1997 Chevrolet introduced the LS1 in the C5 Corvette. This
is an aluminum block engine which produces 345HP and 340 ft/lb torque. These
engines do not have distributors. All timing is done via a crank shaft and
camshaft position sensor. The reluctor for engine timing is secured, internally,
to the crankshaft at the rear of the block. There is a separate ignition coil
for each cylinder. 1999 The 4.8L-LR4 / 5.3L-LM7 / 6.0L-LQ4 engines appeared
in the GM trucks for the 1st time. These engines are of the same basic design
as the LS1, in fact many of the parts are interchangeable. There will be some
neat combinations made in the near future by swapping crankshafts etc.
# # #
If you're in San Antonio please stop by and say hello, or
email us at fuelinjection@fuelinjection.com.
Copyright © 1996-2005 Fuel Injection Specialties, 11051 Wye Drive, San
Antonio, TX 78217
Phone: 210.654.0774, Fax: 210.654.1444
