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Discussion Starter #1
Does anyone know is a 2004 4.3 will work in a 2000 Silverado? I have the engine, the new one doesn't have egr so I will swap the intake and exhaust manifold. they both have counter balance and everything else seems the same, just didn't want to waste the effort if it doesn't work. Thanks
 

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Should work. And they make egr delete kits. Just use a gasket and a plug. What I did with my headers that came set up for EGR I used a gasket
 

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2001+ 4.3's use a "Flat Response" knock sensor that has a 2 pin connector/2 wires
2000 and back used a "Resonant" knock sensor with a single pin/single wire.

Also your 2004 4.3 will have roller fulcrum rocker arms, 2000 4.3 will have conventional stamped rockers.

I swapped a 2003 4.3 into a 2000 GMC Envoy. I just drilled out the smaller knock sensor hole on the 2003 4.3 and then threaded the new hole so that I could retain the stock 2000 4.3 knock sensor. You want to keep the PCM and knock sensor as a matched pair so that PCM recalibration isnt required.

The 2004 4.3 should also have the upgraded MPFI setup that replaces teh poppets of the seock CSFI(Central Sequential Fuel Injection).

These are the V8 equivalent, but its the same deal with the 4.3, although the 305/350 Vortec never came with the upgraded MPFI spider, they came equipped with the CSFI poppets spiders.
CSFI spider top, MPFI spider bottom. Notice the actual mini fuel injectors at the end of each spider leg on the MPFI spider. Both spiders flow the same at 23.1 lb/hr @ 63psi. So recalibrating the IFR(Injector Flow Rate) in the PCM isnt needed.
spidercomparo.jpg


Its a pretty straightforward swap.

peace
Hog
 

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Discussion Starter #4
thanks guys. I did find the knock sensor different and thought of drilling but was kind of scared. That's great info on the injectors also. its a fixer upper I got for my son, engine was shot. I didn't realize the 4.3s are so pricey. I came across this one with low miles and decided to take the gamble. I felt confident it would work with the intake swap until a friend said the timing was different . That had me worried but the distributor and all the sensors look the same besides the knock sensor. Thanks again I will proceed with the swap and let yall know how it goes.
 

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The 2000 4.3 and the 2004 4.3 share the same distributer. Since all spark/ignition timing is controlled via the PCM. This cannot be adjusted unless you recalibrate the PCM. There is Camshaft Position retard that needs to be set, on the V8's its plus 2° or minus 2°. On the V6's the spec is a lot looser than that, something like plus or minus 7°. You set this by "clocking" the distributer with the distributer hold down loosened. Be sure to hold the rpm at 1000rpm while adjusting the CMP retard or the value wont change on the scan tools displayed.

This is a 2010 4.3 Vortec V6, RPO LU3. Notice the distributer at the same place as the distributer you have. This distributer has 3 coils on it.
2010lu3.jpg


Here is a 2007 Vortec 4.3 RPO LU3
200743.jpg


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Changes made to 4.3 Vortec for MY2001
"Vortec 4300" 4.3L V6 (L35) Features & Benefits

OVERVIEW
A new Powertrain Control Module highlights a list of refinements in the L35 V6. The low-end torque delivery of an overhead-valve engine, matched with continued improvements in noise, vibration and harshness control and the latest electronic controls keep the Vortec 4300 at the forefront of V6 truck engines.

NEW OR CHANGED FOR 2001 MODEL YEAR

•Powertrain Control Module (PCM) separated from Vehicle Control Module (VCM)
•Detonation Control Improvements
•Air Injection Reaction for Sierra
•Denso Heated Oxygen Sensor for Export to Japan
•On-Road Vapor Recovery (ORVR) System on Jimmy and Safari
•New Cam Bearings
•New Crank Sensor
•New Alternator Ratings
•New Air Cleaner and Mass Air Flow (MAF) Sensor for GMC Savana
•Revised Oil Fill Tube for Chevrolet Express and GMC Savana
•Extended Oil Change Interval for Sierra
•New Starter Motor
•Sleeveless Coolant Sensor
•Improved Manifold Absolute Pressure (MAP) Sensor

CUSTOMER BENEFITS

NEW PCM
The L35 uses a new Powertrain Control Module (PCM) which manages all powertrain control functions. Control of the L35 had previously been left to a Vehicle Control Module, which managed both powertrain and chassis functions, including anti-lock brake systems.

The new 512-kilobyte PCM is mounted on the intake manifold, and communicates with the adjacent VCM via a data bus. The PCM requires revisions to the L35's wiring harness. The customer will notice no change in engine performance specifically attributable to the new control system, yet the L35 PCM offers several advantages over the VCM.

It reduces cost compared to the integrated VCM. More importantly, it gives the L35 the latest-generation electronic controls, and it gives Powertrain full responsibility for engine management. Powertrain engineers developed software for the PCM independently of vehicle platform teams.

The PCM itself incorporates two custom integrated circuits. One controls the fuel pump, exhaust gas recirculation and transmission; the other primarily controls ignition timing and knock sensing. The dual-circuit design trims weight and improves reliability by reducing the number of external wiring connections.

BETTER KNOCK CONTROL
A new "flat response" knock sensor greatly reduces the possibility of detonation, or pre-ignition of fuel before the spark plug fires. Detonation presents itself to the driver as a loud, unpleasant knocking sound and vibration from the engine bay. Mounted at the rear of the engine, the new, more sophisticated sensor "listens" better than the old: It's able to more accurately separate knock from the myriad of sounds produced by an internal combustion engine. The new PCM uses data from the knock sensor to adjust ignition timing accordingly. The flat-response sensor provides the most advanced detonation control available. Combined with the PCM and new crank sensor, it virtually eliminates engine knock regardless of fuel grade.

AIR FOR SIERRA
L35s installed in Sierra pickups with manual transmissions will be fitted with a Secondary Air Injection Reaction (AIR) system. AIR lowers exhaust emissions by injecting warm, fresh air into the combustion process to create an exothermic reaction. The reaction creates heat and warms the catalytic converters more quickly, speeding catalyst light-off and reducing emissions during cold starts--a critical phase in certification tests.

The system requires an air pump, air delivery hoses and solenoid control and shut-off valves. Exhaust manifolds on AIR-equipped L35s are modified with a boss that delivers injected air to the exhaust ports. With AIR, the L35 achieves National Low Emission Vehicle (NLEV) certification in Sierras equipped with manual transmissions. Because of variations in the certification procedure, the L35 does not require AIR for NLEV status in automatic-equipped Sierras.

LOWER EMISSIONS FOR JAPAN
L35s destined for Japan will be fitted with a new Denso oxygen sensor with a 6.6-watt heating element. The sensor reaches full operating temperature more quickly, and equips the L35 to be an "export" Low Emissions Vehicle (XLEV).

ORVR INTRODUCED
The Jimmy and Safari are now equipped with an On-Road Vapor Recovery System. ORVR keeps gasoline vapor from escaping into the atmosphere. The L35 system collects vapor in a 3.1-liter evaporative cannister, and is designed to the stringent .020 inch leak detection standard.

CAM BEARINGS
The cam bearings are manufactured from a new alloy with less lead and more aluminum to improve durability and extend the anticipated useful life of the engine.

ALTERNATORS
The alternator on the L35 is now monitored by the PCM for proper charge rate and operation. The standard alternator in the Sonoma, Blazer, Jimmy, and Safari delivers 100 amperes of output. A 105-amp alternator is optional on the Safari and standard on the Sierra and Savana. Savana's can be upgraded with a 130-amp alternator.

EXTENDED OIL LIFE
New computer algorithms extend the maximum oil change interval for L35s in the Sierra. The maximum permissible interval is 10,000 miles, compared to 7,500 in 2000. The Powertrain Control Module records engine temperature and length of operation at a given temperature, then indicates an oil change when it's actually needed. With new data on real-world customer use, Powertrain engineers have adjusted the software to allow the longer intervals. That means more convenience for the customer and less environmental impact.

STARTER
The new starter motor draws less amperage than the starter used for model year 2000, yet retains the same cold cranking rating. That means equal starting power with less drain on the battery. The starter is also lighter, and costs less to manufacture.

SLEEVELESS COOLANT SENSOR
The coolant temperature sensor uses a plastic insulator to protect electrical leads inside the brass housing, rather than a rubber sleeve. The new sensor reduces the possibility of assembly rejection or shorting in operation.

BETTER MAP
The Manifold Absolute Pressure (MAP) sensor is manufactured to the higher Electro Magnetic Improvement (EMI) standard, which makes it more immune to operational fluctuations in the presence of electrical interference.

CONTINUING FEATURES
The L35's valvetrain was redesigned for model year 2000 to decrease internal friction, reduce noise and improve fuel economy. Low-friction roller pivot rocker arms and roller lifters were introduced. A roller cam chain reduced noise and enhanced durability.

Cam profiles were adjusted to increase low-speed torque without sacrificing high-end horsepower. L35s for California and select states in the Northeast were certified as Low Emissions Vehicle (LEV) compliant.

In recent years, Powertrain engineers have focused on reducing noise and limiting vibration in the Vortec 4300. Accessory mounts have been stiffened. A single-belt accessory drive system with a 100,000-mile belt was developed to reduce both noise and maintenance. The engine block has been stiffened without increasing mass. The cast aluminum oil pan is not only attached to the block, but to the transmission bell housing as well, further increasing overall engine stiffness and limiting vibration. Powertrain's patented sequential central port injection is one of the most precise fuel-delivery systems available, allowing quick starts in all conditions.

With 1 million built annually, the L35 remains one of Powertrain's highest volume engines. It was developed in the mid-1980s by removing two cylinders from the legendary small block V8. A counter-rotating balance shaft was introduced to balance primary crank vibration in the 90-degree block.


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Changes for the 4.3 from the previous year(2002_
Vortec 4300 4.3L V6 (LG3/LU3) Truck Engines

2003 Model Year Summary

RPO L35 Eliminated
Quiet Cam for LU3
Powertrain Control Module and Software with Additional Monitoring Functions
On Road Vapor Recovery (ORVR) for Chevrolet S-10 and GMC Sonoma Crew Cabs
Improved Oxygen Sensors for Chevrolet Astro and GMC Safari
Solid State Oil-Pressure Sensor For Chevrolet Express and Silverado and GMC Savana and Sierra
Common Accessory Drive Fasteners for Express and Savana


FULL DESCRIPTIONS OF NEW OR CHANGED FEATURES

RPO L35 ELIMINATED
All remaining applications for the Vortec 4300 4.3L V6 (L35) have ended, including: the Chevrolet S10, Blazer, and Express, the GMC Sonoma, Jimmy and Savana, 49-state Chevrolet Silverados and GMC Sierras and the P Truck (a square delivery-style truck now manufactured by Workhorse Custom Chassis). In all cases except the P-Truck (see P-TRUCK APPLICATION ELIMINATED), the L35 will be replaced by the LU3 variant of the Vortec 4300, which was introduced for model year 2002 in Chevrolet Astro, GMC Safari, and Silverados and Sierras built for sale in California.

The 4.3L was developed for optimum performance with all types of fuel; differences between the LU3 and L35 lie entirely in the fuel system. The LU3 replaces Sequential Central Port Injection (SCPI) with Multipoint Fuel Injection (MFI), using the same Multec II fuel injectors found in many GM engines. These state-of-the-art injectors feature a stainless-steel director plate. They reduce fuel leakage 66 percent, maintain more consistent performance under hot-fuel conditions and greatly reduce the potential for plugging due to contamination. In the 4.3L LU3, electrical connections are extended from the L35’s centrally located injector drivers to the injectors (operated electrically rather than by a fuel pressure pulse) at the intake ports. The 4.3L LU3’s intake manifold is identical to that used on the L35.

The Vortec 4300 requires slight packaging modifications for installation in the redesigned Express and Savana. The engine is essentially the same as the LU3 used in the Silverado and Sierra, but the dipstick and oil-fill tubes are extended for application in full-size vans. The oil pan requires a slight scallop in its sump to accommodate the van’s front suspension.

P-TRUCK APPLICATION ELIMINATED
With production of the heavy-duty 4.3L L35 ending, the Vortec 4300 will no longer be offered in the P Truck.

QUIET CAM FOR LU3
The 4.3L LU3 will be equipped with a ``quiet cam’’ designed to reduce vibration and mechanical noise at both idle and high engine speeds. The new camshaft has no effect on engine output or dynamic performance. Maximum valve lift and duration do not change, but the lobes have been re-profiled to keep the valve lifters in full contact with the cam as the lobes ramp down. The cam significantly reduces noise at high rpm and delivers what customers perceive as a smooth, strong, confident engine sound.

POWERTRAIN CONTROL MODULE AND SOFTWARE WITH ADDITIONAL MONITORING FUNCTIONS
A new Powertrain Control Module (PCM), called P59, manages the 4.3L LU3. This PCM increases clock speed from 21 to 24 MhZ and doubles memory (1.1 megabyte) compared to its predecessor. It also provides one of the most sophisticated engine control systems in the industry. The P59 is common to the LU3 and all gasoline-powered Vortec V8 truck engines.

Commonality offers the advantage of reducing inventory complexity and increasing efficiency at various assembly plants. More important, the P59 offers the most precise engine management possible, optimizing performance according to temperature or operating conditions and virtually eliminating unintended variation in every function it controls, from ignition timing to fuel delivery to transmission shift points. It also allows GM Powertrain engineers to monitor more engine operations and improves the accuracy and robustness of the OBDII (for On-Board Diagnostics) system.

For example, the PCM now measures electrical current flowing to the oxygen (O2) sensors on vehicles equipped with the 4.3L LU3 (crucial components of the emissions-control system). Previously, the O2 sensors were monitored with a time-to-activity algorithm, which required more measurement latitude to ensure proper operation. The new PCM immediately reports a malfunction in an O2 sensor with virtually no margin for misreporting. It also allows a new Engine Off Natural Vacuum diagnostic (EONV) for the On Road Vapor Recovery system (ORVR), which reduces evaporative emissions by preventing gasoline vapor from escaping the vehicle into the atmosphere. With EONV, the PCM actually continues to operate when the engine is turned off, monitoring pressure in the fuel tank and ORVR system. If pressure bleeds off more quickly than ambient temperature and other conditions indicate, the PCM can determine whether the system has a leak, even when the vehicle is parked. The new PCM ensures that the LU3 operates according government emissions regulations. And thanks to its precision, it will also reduce the number of false alarms-- OBDII ``service engine’’ warning lights--that require dealer intervention.

ON ROAD VAPOR RECOVERY (ORVR) FOR CHEVROLET S-10 AND GMC SONOMA CREW CABS
S-10 and Sonoma Crew Cabs equipped with the 4.3L LU3 now carry an ORVR system. The system is virtually identical to that on other trucks powered by the LU3. The evaporative canister has 3.1 liters volume, with a leak-detection standard of .020 inches. While there is no obvious change for the customer, ORVR reduces evaporative emissions by preventing gasoline vapor from escaping into the atmosphere. The LU3’s OBDII system constantly monitors ORVR. Leaks greater than .020 inches in diameter would be indicated with a warning light in the vehicle’s instrument panel.

IMPROVED OXYGEN SENSORS FOR CHEVROLET ASTRO AND GMC SAFARI
The 4.3L LU3s installed in the Astro and Safari are equipped with new O2 sensors. The new sensors are required for the new PCM current-monitoring function. They also heat more quickly, allowing the exhaust emissions system to achieve “closed loop’’ operation--maximum emissions reduction--in about half the time.

SOLID-STATE OIL PRESSURE SENSOR FOR CHEVROLET EXPRESS AND SILVERADO AND GMC SAVANA AND SIERRA
The 4.3L LU3s built for these four applications use a fully electronic, solid-state oil pressure sensor (other applications have an analog/mechanical sensor). The Express, Silverado, Savana and Sierra have electronic instrument packages, and the solid-state sensor is required to drive the oil pressure gauge.

COMMON ACCESSORY DRIVE FASTENERS FOR EXPRESS AND SAVANA
With redesign of the Express and Savana, all accessory drive fasteners on 4.3L LU3s built for this application match those on Vortec V8s. Nuts and bolts for alternator and AC compressor mounting brackets, pulleys, etc., will have the same size. This allows assembly associates to install accessories on various engines without changing tools.


OVERVIEW
The Vortec 4300 remains one of GM Powertrain's highest volume engines. This 4.3-liter V6 was developed in the mid-1980s by removing two cylinders from the legendary small block V8. Counter-rotating balance shafts were introduced to balance primary crank vibration in the 90-degree block. The low-end torque delivery of an overhead-valve engine matched with continued improvements in noise, vibration and harshness control and the latest electronic controls have kept the Vortec 4300 at the forefront of V6 truck engines.

The Vortec 4300 remains one of the best V6 engines available. It delivers excellent torque and good specific output in an economical, high-value package, and it continues to surpass increasingly stringent government emissions standards.

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Changes for MY2004
Vortec 4300 4.3L V-6 (LU3)

2004 Model Year Summary

Regular-Cab Chevrolet S-10 and GMC Sonoma applications eliminated
Timing chain tensioner
Two-ply fuel pressure regulator

FULL DESCRIPTIONS OF NEW OR CHANGED FEATURES

STANDARD-CAB CHEVROLET S-10 AND GMC SONOMA APPLICATIONS ELIMINATED
With introduction of the all-new 2004 Chevrolet Colorado and GMC Canyon pickups, production of Regular Cab S-10s and Sonomas ceases. The Vortec 4300 will continue through 2004 in Crew Cab versions of the S-10 and Sonoma.

TIMING CHAIN TENSIONER
All Vortec 4300s built for vehicle installation are now equipped with a timing chain tensioner. This shoe-type tensioner mounts to the engine block and rests on the chain, which connects the crank and camshafts. It maintains optimal chain tension for the life of the engine and eliminates a minor flapping motion that can develop as the chain stretches with mileage. The tensioner ensures that the timing chain operates as smoothly and quietly as new, even as the Vortec 4300 accumulates high mileage.

TWO-PLY FUEL PRESSURE REGULATOR
A new fuel pressure regulator with a two-ply diaphragm replaces the previous regulator, which had a single-ply diaphragm. The new regulator works as a redundant safety measure with the intake manifold check valves, which were installed in the Vortec 4300 in model year 2003 to stop the flow of fuel between the fuel line and the engine in the event of a vehicle rollover.

The new pressure regulator is installed in the same location as the previous regulator, and maximum fuel pressure remains the same. The two-ply regulator more effectively manages pulse characteristics in the fuel line created by the check valves, ensuring the same quiet operation of the fuel system.

OVERVIEW
The Vortec 4300 remains a workhorse in GM Powertrain's line of truck engines, and a standard for industrial and marine application around the globe. Vehicle development teams continue to rely on this classic 90-degree V-6 for some very practical reasons: It delivers outstanding torque and good specific output in an economical, high-value package, and it continues to surpass increasingly stringent government emissions standards.

This V-6 was developed in the mid-1980s by removing two cylinders from Powertrain's legendary small block V-8. A counter-rotating balance shaft was introduced to balance primary crank vibration. The low-end torque delivery of an overhead-valve engine, combined with continued improvements in noise, vibration and harshness control and the latest electronic controls, have kept the Vortec 4300 a popular choice with truck customers.

In recent years, Powertrain engineers have focused on reducing noise and limiting vibration. Accessory mounts have been stiffened. A single-belt accessory drive system with a 100,000-mile belt was developed to reduce both noise and maintenance. The engine block has been stiffened without increasing mass. The cast aluminum oil pan is not only attached to the block, but to the transmission bell housing, further increasing overall powertrain stiffness. The valvetrain was redesigned for model year 2000 to decrease internal friction, reduce noise and improve fuel economy. Low-friction roller pivot rocker arms and roller lifters were introduced. A roller cam chain reduced noise and enhanced durability. Cam profiles were adjusted in 2003 to reduce operational noise at high rpm without reducing horsepower or torque.

For 2003, the Vortec 4300 was equipped with Powertrain's P59 Powertrain Control Module – one of the most powerful, sophisticated engine management systems extant. A new RPO (LU3) was extended to all North American applications, replacing sequential central port fuel Injection (SCPI) with multipoint injection (MFI). This system is fired electrically, rather than with fuel pressure pulses, and it uses state-of-the-art Multec II injectors, which reduce fuel leakage by 66 percent, maintain more consistent performance under hot-fuel conditions, and greatly reduce potential for clogging due to fuel contamination.

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
 

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2001+ 4.3's use a "Flat Response" knock sensor that has a 2 pin connector/2 wires
2000 and back used a "Resonant" knock sensor with a single pin/single wire.

Also your 2004 4.3 will have roller fulcrum rocker arms, 2000 4.3 will have conventional stamped rockers.

I swapped a 2003 4.3 into a 2000 GMC Envoy. I just drilled out the smaller knock sensor hole on the 2003 4.3 and then threaded the new hole so that I could retain the stock 2000 4.3 knock sensor. You want to keep the PCM and knock sensor as a matched pair so that PCM recalibration isnt required.

The 2004 4.3 should also have the upgraded MPFI setup that replaces teh poppets of the seock CSFI(Central Sequential Fuel Injection).

These are the V8 equivalent, but its the same deal with the 4.3, although the 305/350 Vortec never came with the upgraded MPFI spider, they came equipped with the CSFI poppets spiders.
CSFI spider top, MPFI spider bottom. Notice the actual mini fuel injectors at the end of each spider leg on the MPFI spider. Both spiders flow the same at 23.1 lb/hr @ 63psi. So recalibrating the IFR(Injector Flow Rate) in the PCM isnt needed.
spidercomparo.jpg


Its a pretty straightforward swap.

peace
Hog
Can you tell me or rember where the knock sensor is located on the 2000 4.3 my buddy had the same swap to a 2003 4.3 as you thanks Kevin
 
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