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Old 03-06-2008, 05:54 PM
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Default LT1 FAQ and Tech

General LT1 FAQ and Tech


Before you ask a question
Optispark/Ignition
LT1 Specs and changes from 93-97
Location of everything on the car

How to's:
Bypass VATS Resistor Pellet
Install an Electric Water Pump
Pull codes on OBDI (93-95)
Test A Fuel Pump and Regulator
Remove an LT1 from the Bottom

Budget LT1 Performance Mods


Note: Links will open in a new tab/window
__________________
1995 Z28: Moroso CAI/Kooks 1 3/4 LT Headers/catted Y/!muffler/Hooker tips. 17X9.5 Chrome Z06 wheels
1995 Impreza: EJ22T/Gen I JDM STi 5-sp swap, TD04 @15 psi w/ front-mount, Legacy GT 4-wheel disk, OZ Racing Prodrive wheels

Click for Camaro Exhaust Clip

Last edited by craby; 04-07-2012 at 12:27 AM.
  #2  
Old 03-06-2008, 05:58 PM
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Default RE: LT1 FAQ and Tech (Under Construction)

Before You Ask a Question

If are looking for useful help in resolving a problem, You need to provide as much info as possible.
In particular:

1) year of car
2) Model of car
3) Engine: V8 or V6
4) Transmission type; auto or manual
5) Modifications performed
6) Clear & detailed description of trouble (in English)
7) Any recent work done to car before trouble started.
8) What have you done so far

Please Visit http://shbox.com/page/index.html if you are looking for wiring diagrams, pictures of component locations. Many tech How-to's are answered on this page as well.

If your LT1 powered car is having driveability issues, such as rough running, hesitation, misfires, etc.., and you are looking for help. You will get better results by doing the following:

1) Check to see if the SES lite is lit, or flashing.
2) Get the car scanned, regardless of the SES lite status, and check for active and retained codes.

Places like Auto Zone offer free scans on OBDII cars. 1996 & newer. OBDI cars, you may have to buy a scanner or pay someone to do it.
__________________
1995 Z28: Moroso CAI/Kooks 1 3/4 LT Headers/catted Y/!muffler/Hooker tips. 17X9.5 Chrome Z06 wheels
1995 Impreza: EJ22T/Gen I JDM STi 5-sp swap, TD04 @15 psi w/ front-mount, Legacy GT 4-wheel disk, OZ Racing Prodrive wheels

Click for Camaro Exhaust Clip

Last edited by 95slvrZ28; 08-06-2009 at 10:58 AM.
  #3  
Old 03-06-2008, 06:09 PM
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Default RE: LT1 FAQ and Tech (Under Construction)

Optispark/Ignition

Optispark Failure Symptoms:
Before ripping out the optispark, make sure all grounds, wires, coil, coil control module, and associated wiring are good, as they are much cheaper and easier to change than the Opti.

Failure symptoms:
Engine dies suddenly and won't restart
Engine starts, but dies almost immediately
Extensive cranking needed to start engine
Rough idle
Sputtering under load
Backfiring
Trouble reaching high RPM
Black smoke from exhaust
Poor performance once engine is warmed up
Weak spark at plugs
On OBDI engines codes 16, 36, 42 may be set, but not always.

Optispark-Understanding and Modifying:

http://www.gmhightechperformance.com...ing/index.html
General Optispark Information:

What is the Opti-Spark Distributor?
Click the image to open in full size. When GM introduced the LT1 engine in the 1992 Corvette, it was a major advance in V8 pushrod engine technology. Reverse-flow cooling helped it run higher compression ratios on pump gas than ever before. Multi-port fuel injection with a newly designed intake allowed the engine to get incredible fuel economy while maintaining good top end power. Best of all, when GM started installing these engines in the 1993 Camaro/Firebird platform and the 1994 Caprice/Impala SS platform, true high-performance small block power was made available to the masses. For the most part, the LT1 earned every bit of the praise it received.
After people put some mileage on their LT1-powered cars, Opti-Spark Ignitions began to fail at a fairly high rate. Vehicles operated in wet climates were even more susceptible to problems. What was causing problems with the Opti-Spark?
In order to understand the problems with the Opti-Spark Ignition, a brief description of the system is necessary. Quite simply, the Opti-Spark was a new distributor design that debuted on the 1992 Chevrolet Corvette LT1 V8. All LT1 (5.7L) and L99 (4.3L) V8 engines made between 1992 and 1997 were equipped with the Opti-Spark distributor. This would include all 1992-1996 Corvette, 1993-1997 Z28 and Trans Am/Formula Firebird, and 1994-1996 Caprice, Impala SS, Buick Roadmaster, and Cadillac Fleetwood applications. The Opti-Spark distributor was driven directly off the front of the camshaft. Consequently, the LT1 and L99 engines featured many design changes from the "old-style" small block to accommodate the new "front-mount" distributor location.
The term "Opti-Spark" describes the two functions of this distributor: optical ("Opti") engine speed and position sensing, and high voltage ignition distribution to the eight spark plugs ("Spark"). To perform these tasks, the Opti-Spark distributor contains a high-resolution engine speed encoder, a low-resolution engine position encoder, and a standard distributor cap and rotor assembly.
The high-resolution encoding is done with a 360-tooth trigger wheel spinning at camshaft speed. An optical sensor reads these spinning teeth, and creates a simple 0 or 5 volt signal, depending on whether an opening in the teeth is or is not present. As the trigger wheel spins with the engine, this 0 or 5 volt signal becomes a square-shaped voltage signal, or "square wave" in technical terms. This signal is then sent to the engine management computer to determine engine speed.
__________________
1995 Z28: Moroso CAI/Kooks 1 3/4 LT Headers/catted Y/!muffler/Hooker tips. 17X9.5 Chrome Z06 wheels
1995 Impreza: EJ22T/Gen I JDM STi 5-sp swap, TD04 @15 psi w/ front-mount, Legacy GT 4-wheel disk, OZ Racing Prodrive wheels

Click for Camaro Exhaust Clip

Last edited by 95slvrZ28; 08-06-2009 at 11:05 AM.
  #4  
Old 03-06-2008, 06:14 PM
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Default RE: LT1 FAQ and Tech (Under Construction)

LT1 Specs and Changes from 93-97

LT1 Specs from GM Documentation:

5.7L V8 LT1

Features


Sequential-port fuel injection.

A low-restriction three way catalyst after Y pipe (93-95)
A low-restriction three way catalyst on each cylinder bank (96+ & California).

Reverse-flow cooling system channels cooler water to the cylinder heads first.

Gear-driven water pump ensures coolant flow even if accessory belt breaks.

A short runner intake manifold with multi-port fuel injection, high compression pistons, free-flowing aluminum cylinder heads, and a hydraulic roller cam.

Heart-Shaped combustion chambers enhance combustion effciency (fast burn heads)

Type:90 Degree V
Longitudinal 5.7 V8 350ci
Firing Order:1-8-4-3-6-5-7-2 ;
Left Bank:1-3-5-7;
Right Bank:2-4-6-8
Compression Ratio: 10.5:1


Valve Config : Overhead Valves; Manufactured: Flint, Michigan ; Valve Lifters: Hydraulic

Bore x Stroke: 4.00x 3.48 in. ; Fuel System: Sequential-Port Fuel Injection;

Horsepower:
265 hp@ 5000 RPM single Catalyst
275 hp@ 5000 RPM dual Catalyst

Torque: 325 ft lbs; Block:Cast Iron ;Cylinder Heads:Cast Aluminum; Intake Manifold:Cast Aluminum

Fuel: 91 octane; Pistons: Cast Alum. (impacted) ;Connecting Rods: Forged steel early models, Powdered iron late models

Crankshaft: Nodular Cast Iron ; Coolant thermostat opens at 180 Degrees F; Fuel Tank Capacity:15.5 Gallons

Fuel Tank Location:rear and above rear axle; Fuel injectors at Inlet Ports; Exhaust is All Stainless-Steel


Transmissions
T-56 Manual Six-Speed

Gear Ratios:
(Man) 1st:2.66
(Man) 2nd:1.78
(Man) 3rd:1.30
(Man)4th:1.00
(Man)5th:0.74
(Man)6th:0.50
(Man)Reverse:2.90
Axle Ratio:3.42
Pinion teeth:12
Ring gear:41


Hydra-matic 4L60E Automatic 4-speed with Overdrive
1st: 3.06
2nd:1.63
3rd:1.00
4th:0.70
Reverse:2.29

Maximum Upshift MPH
1-2nd: 48mph 2-3rd:93mph 3-4th:150mph= 2.73 Axle
1-2nd: 36mph 2-3rd:73mph 3-4th:126mph= 3.23 Axle (performance axle)

Max. Upshift Engine Speed= 5700 RPM

(Auto) Max. Kickdown Speeds
4-3rd: 142mph 3-2nd:86mph 2-1st:29mph=2.73 Axle
4-3rd: 118mph 3-2nd:67mph 2-1st:31mph=3.23 Axle

Axle Ratios:
3.23: Pinion=13 Ring Gear=42 (performance axle)
2.73: Pinion=15 Ring Gear=41

Rear Axle Limited Slip Differential type= Disc Clutches
Antilock Front and Rear Disc Brakes

Standard Tire Size Z28 P235/55R16
Optional Tires: Hi-perfomance Z rated tires P245/50ZR16(With this option car is not speed limited because tires are capable of speeds in excess of 150mph)

Performance Package (RPO CODE 1LE:Intended For Serious Performance Enthusiasts Only)
Includes Engine Oil Cooler and Special Handling Suspension System, Oil cooler also included with performance axle)
Including Larger Stabilizer Bars, Stiffer Shock Absorbers and Bushings.


Competitive Vehicles
Camaro Z28's main competition is Pontiac Trans Am And Formula. Ford Probe Gt, Ford Mustang Gt, Eclipse/Laser/Talon (Performance versions w/turbo and all wheel drive) Dodge Stealth,Toyota Celica GT and GTS,Toyota Supra,and Nissan 300zx.

LT1 Cooling Specs:

There are two different ways that the f
__________________
1995 Z28: Moroso CAI/Kooks 1 3/4 LT Headers/catted Y/!muffler/Hooker tips. 17X9.5 Chrome Z06 wheels
1995 Impreza: EJ22T/Gen I JDM STi 5-sp swap, TD04 @15 psi w/ front-mount, Legacy GT 4-wheel disk, OZ Racing Prodrive wheels

Click for Camaro Exhaust Clip

Last edited by 95slvrZ28; 08-06-2009 at 11:08 AM.
  #5  
Old 03-06-2008, 06:20 PM
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Default RE: LT1 FAQ and Tech (Under Construction)

How To Bypass a VATS Resistor Pellet

http://shbox.com/1/pass_key.html
http://shbox.com/1/4th_gen_tech2.html#pass_key
http://shbox.com/1/vats_bypass.jpg

VATS Key Resistor Chart:

Pellet Code Key Resitance In Ohms

Nominal Low High
1402386438
2523502564
3 681 654 728
4887 852 942
5 1130 1085 1195
6147014111549
718701795 1965
8 2370 2275 2485
9 30102890 3150
103740 3590 3910
114750 4560 4960
12 6040 5798 6302
13&nbs
__________________
1995 Z28: Moroso CAI/Kooks 1 3/4 LT Headers/catted Y/!muffler/Hooker tips. 17X9.5 Chrome Z06 wheels
1995 Impreza: EJ22T/Gen I JDM STi 5-sp swap, TD04 @15 psi w/ front-mount, Legacy GT 4-wheel disk, OZ Racing Prodrive wheels

Click for Camaro Exhaust Clip

Last edited by 95slvrZ28; 08-06-2009 at 11:10 AM.
  #6  
Old 03-06-2008, 06:22 PM
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Default RE: LT1 FAQ and Tech (Under Construction)

How To Install an Electric Water Pump

GM LT-1 Meziere Electric Water Pump

In The Box You Will Find:

1 Electric Water Pump
1 1-1/8 deep brass freeze plug PC25B
1 Wiring harness w/ 20 amp fuse
2 Contingency stickers

To Do The Job You Will Need:
· A few metric hand tools
· Hydraulic press
· Scraper or wire brush
· Brake cleaner
· Recommended sealant; Form A Gasket (aviation), Form A Gasket 2 (Non-Hardening), Gaskacinch or RTV silicone
· Factory water pump housing to block gaskets P/N 10128343
· Factory inspection cover o-ring P/N 10128329
· Grease or Vaseline (petroleum jelly)

Disassembly
Remove factory water pump housing. Remove the six-bolt inspection cover. Clean the mounting surface on the housing and the engine block. At this point the stock mechanical pump components must be removed from the housing (i.e. impeller and bearing / seal assy.). Some technical experience is required. If you do not have access to the proper equipment or feel unqualified, please consult an automotive machine shop for help in completing this part of the job.

Place the housing face up in the hydraulic press resting the gasket surface centered on the shaft. It is necessary to support the back of the pump housing near the water neck to prevent it from rocking back when force is applied by the press. Use a pin or dowel (about 5/16 x 1 ½) to press the bearing assembly out of the impeller and housing.

Assembly
Clean the bearing bore and install the supplied freeze plug from the inside of the pump use Permatex Form A Gasket or Loctite Sleeve/Bearing retainer on the bore. You may choose to plug some of the factory water ports at this time. Now you are ready to reinstall the pump housing, the Meziere pump can be mounted before or after the pump housing is installed on the engine. Use recommended sealant on the factory-mounting gasket. No sealant is used on the o-ring seal grease or Vaseline can be used to lubricate the o-ring to prevent pinching or twisting. Reuse the factory inspection cover bolts to attach the Meziere pump (do not over tighten).

Wiring
The BLUE wire connects to positive (+)
The BLACK wire connects to chassis ground or battery negative (-)
TO AVOID MOTOR FAILURE, be sure to use the fuse holder supplied with the harness or install your own 15 to 20 amp fuse and holder WARNING: NOT USING A PROTECTION CIRCUIT CAN VOID YOUR WARRANTTY.
Running
Fill the cooling system. Replace fill cap and turn on pump.&nbs
__________________
1995 Z28: Moroso CAI/Kooks 1 3/4 LT Headers/catted Y/!muffler/Hooker tips. 17X9.5 Chrome Z06 wheels
1995 Impreza: EJ22T/Gen I JDM STi 5-sp swap, TD04 @15 psi w/ front-mount, Legacy GT 4-wheel disk, OZ Racing Prodrive wheels

Click for Camaro Exhaust Clip

Last edited by 95slvrZ28; 08-06-2009 at 11:22 AM.
  #7  
Old 03-06-2008, 06:25 PM
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Default RE: LT1 FAQ and Tech (Under Construction)

How To Pull Codes on OBDI (93-97)

1993- Still using the old ECM. Codes can be flashed by shorting the A & B terminals on the diagnostic connector. Turn the key ON, but do not start the engine
Early 1994- GM went to the PCM and codes cannot be flashed. Early 94s use the regular OBDI diagnostic connectors and can be scanned with most OBDI scanners. However; plain old code readers do not usually work.
Late 94 and 95- Still OBDI, but for some mysterious reason GM used aOBDII diagnostic connectors. These can be scanned with a OBDI scanner using an adapter cord or by making up one.
Home made adapter info- http://shbox.com/1/xraycable.jpg

This is a source for cables to connect 94-95 Camaro ALDL port to a PC. It is a strange set up because although the 94-95 cars are OBD1, the ALDL port is configured for OBD2.
http://www.pcmperformance.com/cables.html
__________________
1995 Z28: Moroso CAI/Kooks 1 3/4 LT Headers/catted Y/!muffler/Hooker tips. 17X9.5 Chrome Z06 wheels
1995 Impreza: EJ22T/Gen I JDM STi 5-sp swap, TD04 @15 psi w/ front-mount, Legacy GT 4-wheel disk, OZ Racing Prodrive wheels

Click for Camaro Exhaust Clip

Last edited by 95slvrZ28; 08-06-2009 at 11:24 AM.
  #8  
Old 03-06-2008, 06:28 PM
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Default RE: LT1 FAQ and Tech (Under Construction)

How To Test an LT1 Fuel Pump & Regulator

FUEL PUMP & PRESSURE REGULATOR TEST:

1) Connect a Fuel Injection pressure gauge (available from most part stores) to the test port on the FI rail (similiar to a tire valve). Be carful as fuel under pressure may spray out.

2) With the key ON & engine OFF (cycle the key ON-OFF several times as pump only runs for 2 seconds) the pressure should be 41-47 PSI. (If NOT: weak pump, dead pump, or no power to pump)

3) Turn key OFF, pressure should NOT drop more than 1-2 PSI and then hold steady. (If NOT: fuel line leak, injector leak, regulator leak, fuel pump check ball leaking)

4) Let engine idle, pressure should drop 3-10 PSI from the reading in step 2. ( If NOT: bad pressure regulator, vacuum leak to pressure regulator.

5) WOT (car accelerating at full throttle, pressure should hold @ 41-47 PSI. Good to have two people, one to drive and one to watch gauge (If NOT: dirty fuel filter, weak pump, bad pressure regulator)
__________________
1995 Z28: Moroso CAI/Kooks 1 3/4 LT Headers/catted Y/!muffler/Hooker tips. 17X9.5 Chrome Z06 wheels
1995 Impreza: EJ22T/Gen I JDM STi 5-sp swap, TD04 @15 psi w/ front-mount, Legacy GT 4-wheel disk, OZ Racing Prodrive wheels

Click for Camaro Exhaust Clip

Last edited by 95slvrZ28; 08-06-2009 at 11:38 AM.
  #9  
Old 03-06-2008, 06:30 PM
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Default RE: LT1 FAQ and Tech (Under Construction)

How To Remove an LT1 from the Bottom

http://www.michiganspeed.com/enginepull/index.html
__________________
1995 Z28: Moroso CAI/Kooks 1 3/4 LT Headers/catted Y/!muffler/Hooker tips. 17X9.5 Chrome Z06 wheels
1995 Impreza: EJ22T/Gen I JDM STi 5-sp swap, TD04 @15 psi w/ front-mount, Legacy GT 4-wheel disk, OZ Racing Prodrive wheels

Click for Camaro Exhaust Clip

Last edited by 95slvrZ28; 08-06-2009 at 11:46 AM.
  #10  
Old 03-06-2008, 06:38 PM
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Default RE: LT1 FAQ and Tech (Under Construction)

Budget LT1 Performance

This is taken from the April, 2008 issue of GM High Tech performance. ET reduction and MPH gain is for 1/4 mile track.

QTP Exhaust Cutout:
$45, +12 RWHP, -0.1 ET, +1 MPH, hard

K&N Cold-Air Induction:
$199, +15 RWHP, -0.1 ET, +1 MPH, medium

Hooker Catback:
$330, +15 RWHP, -0.1 ET, +1 MPH, medium

Crane 1.6 Roller Rockers:
$369, +7 RWHP ???, -0.05 ET, +0.05 MPH, medium

Meziere Electric Water Pump:
$219, +8 RWHP, -0.05 ET, +1 MPH, hard

Drag Radials:
$400, +0 RWHP, -0.3 ET, +1 MPH, hard (easy for tire guy)

Nitrous Express Wet Kit:
$585, +100 RWHP, -0.8 ET, +9 MPH, hard

Precision Industries Torque Converter:
$699, +0 RWHP, -0.3 ET, +1 MPH, hard
__________________
1995 Z28: Moroso CAI/Kooks 1 3/4 LT Headers/catted Y/!muffler/Hooker tips. 17X9.5 Chrome Z06 wheels
1995 Impreza: EJ22T/Gen I JDM STi 5-sp swap, TD04 @15 psi w/ front-mount, Legacy GT 4-wheel disk, OZ Racing Prodrive wheels

Click for Camaro Exhaust Clip

Last edited by 95slvrZ28; 08-06-2009 at 11:49 AM.
Old 03-06-2008, 06:38 PM
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