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GM Vortec Injector upgrade Question

This is a discussion on GM Vortec Injector upgrade Question within the Port Injection (96+ / OBD-II) forums, part of the Performance category; Does the computer need to be reflashed with a different program when changing from OE poppets to the GM upgraded ...

  1. #1
    TELL IT LIKE IT IS fire730's Avatar
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    GM Vortec Injector upgrade Question


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    Does the computer need to be reflashed with a different program when changing from OE poppets to the GM upgraded spider assembly? I am having some driveability problems since I did the upgrade and I am running out of ideas.
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    98 Burban Drop'd On 22's Brahma Brian's Avatar
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    Re: GM Vortec Injector upgrade Question

    Quote Originally Posted by fire730
    Does the computer need to be reflashed with a different program when changing from OE poppets to the GM upgraded spider assembly? I am having some driveability problems since I did the upgrade and I am running out of ideas.
    Not to my knowledge, my master tech at work has all the parts to do his 96 Tahoe sitting on my desk to be swapped soon, I'll find out then for sure, but he already told me it's a straight swap...

    I will most likely do mine later this year as well, but I'm not in a hurry for it...

    It probably wouldn't hurt to unhook the battery overnight to clear the RAM...

  3. #3
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    Re: GM Vortec Injector upgrade Question

    Did you check your fuel pressure? Maybe your pump is on its way out.
    97 Gmc Sierra 1500
    Current mods: Flowmaster 40's, K&N FIPK, S10 converter, wait4me tune, LT1 fans, 2" drop shackles, Alpine CDA-9856 head unit.

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    Home of the Snooki punch! CKTA's Avatar
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    Re: GM Vortec Injector upgrade Question

    Quote Originally Posted by fire730
    Does the computer need to be reflashed with a different program when changing from OE poppets to the GM upgraded spider assembly? .
    No.
    2015 Carlisle All Truck Nats info..
    http://www.fullsizechevy.com/forum/o...t-7th-9th.html


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    Re: GM Vortec Injector upgrade Question

    no computer reflash needed, its plug and play.

    What are the drivability issues?
    08 HHR LS - 2.2 | 5 speed | 30 MPG

    98 K1500 Z71 - 204k | L31 | 60E | 3.73's | 3" BL | 33x12.5x15 Dick Cepek F-C II's | Dynomax Ultra Flo X DI/DO | 14 MPG

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  6. #6
    chevy boy
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    Re: GM Vortec Injector upgrade Question

    sounds like maybe a vacuum leak somewhere. make sure you didnt damage the gasket that goes around the spider body and seals against the upper intake gasket. i usually put a little grease around it to, just to help make sure
    1999 1500 nbs- 4.8, 4x4, performabuilt level 2/3000yank, 3.73s, ls6 cam and valve springs, trick front mount 76 and a fully forged 6.0 waiting in the garage.

  7. #7
    the youngest has-been
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    Re: GM Vortec Injector upgrade Question

    double check everything you removed for the job. most of the time its something simple that was overlooked.

    we are all human and make mistakes.
    -mark
    89 blazer 2dr 2wd L31 vortec 355|T56|8.5
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    Registered User 96SLT350's Avatar
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    Re: GM Vortec Injector upgrade Question

    Quote Originally Posted by dalejrfan8
    Did you check your fuel pressure? Maybe your pump is on its way out.
    or filter or kink in fuel line

  9. #9
    98 Burban Drop'd On 22's Brahma Brian's Avatar
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    Re: GM Vortec Injector upgrade Question

    Well we changed mine out at the shop yesterday, and OMG what a GREAT upgrade!

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    Re: GM Vortec Injector upgrade Question

    Quote Originally Posted by Brahma Brian
    OMG what a GREAT upgrade!

    That much of a noticeable difference?

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    98 Burban Drop'd On 22's Brahma Brian's Avatar
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    Re: GM Vortec Injector upgrade Question

    Quote Originally Posted by 5.7L JWL
    That much of a noticeable difference?
    I'd do it again in a second without thinking about it!

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    Re: GM Vortec Injector upgrade Question

    Quote Originally Posted by Brahma Brian
    I'd do it again in a second without thinking about it!
    Thats the same way I felt when I did my Express. Get ready though, if your poppets were getting bad, you will see 1-2mpg increase.
    1997 G1500 Cobra Conversion, 5.7, 4L80E, 3.73 14-bolt 9.5", L31 Marine Intake, CFM TB, 02 MAF, 0411, Custom cam. Doug Thorley Tri-Ys, full exhaust soon.

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    Re: GM Vortec Injector upgrade Question

    Please explain your driveability problems.

    Did you remove the upper intake, or did you have the entire intake assembly off and decide to swap the injection out?

    Did you pull the distributer.

    peace
    PAuly
    97 GMC 2wd RCSB 5.7, s10 2700 footstall, Hooker 24621hkr LT's , 2.5" cats dual 4"pipes exit B4 pass. side tire, custom driveshaft 3.42 G80 FIPK MAF descreen GM/Mercruiser Marine intake manifold 29lb LS2(EV6) injectors Ed Wright PCM(best mod), LT4 KM 14.8@94mph 2.007 4000lbs 122mph

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    Re: GM Vortec Injector upgrade Question

    I love when people start threads looking for answers and then never come back to them...
    08 HHR LS - 2.2 | 5 speed | 30 MPG

    98 K1500 Z71 - 204k | L31 | 60E | 3.73's | 3" BL | 33x12.5x15 Dick Cepek F-C II's | Dynomax Ultra Flo X DI/DO | 14 MPG

    84 S15 Jimmy 2dr 4x4 - engine/tranny all rebuilt

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    Re: GM Vortec Injector upgrade Question


  16. #16
    Registered User 5.7L JWL's Avatar
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    Re: GM Vortec Injector upgrade Question

    A while back I got the dreaded intake coolant leak on the rear driver side. I didn't know about the upgraded poppets while everything was off or I would have changed them(damn). I have 217k on the engine and get high 16's low 17's MPG. Would the poppets be considered worn out at that milage?
    Last edited by 5.7L JWL; 10-15-2008 at 02:55 PM.

    '98 ECSB, Edel Headers, Magnaflow Cats/CatBack
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    98 Burban Drop'd On 22's Brahma Brian's Avatar
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    Re: GM Vortec Injector upgrade Question

    Quote Originally Posted by Fast305
    Thats the same way I felt when I did my Express. Get ready though, if your poppets were getting bad, you will see 1-2mpg increase.
    Yeah, mine apparently were crap and I only have 88K on mine...

    With all the rest of the stuff I have done, my Burban is a BEAST now, before I was embarrassed to pass someone...

  18. #18
    98 Burban Drop'd On 22's Brahma Brian's Avatar
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    Re: GM Vortec Injector upgrade Question

    Quote Originally Posted by 5.7L JWL
    A while back I got the dreaded intake coolant leak on the rear driver side. I didn't know about the upgraded poppets while everything was off or I would have changed them(damn). I have 217k on the engine and get high 16's low 17's MPG. Would the poppets be considered worn out at that milage?
    Um, yeah... To say the least... IMO

  19. #19
    Registered User 5.7L JWL's Avatar
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    Re: GM Vortec Injector upgrade Question

    Thought so! LOL

    '98 ECSB, Edel Headers, Magnaflow Cats/CatBack
    K&N, Pully, Ign.Kit, D/S Rotors, SS Lines, BB 89 Tune
    Built 4L60E w/ Vigilante 2800 Stall
    http://photobucket.com/R3215T3R/ (Toyvrolet Drag Truck/S-10 Drag Truck)Pics.

  20. #20
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    Re: GM Vortec Injector upgrade Question

    Quote Originally Posted by 5.7L JWL
    A while back I got the dreaded intake coolant leak on the rear driver side. I didn't know about the upgraded poppets while everything was off or I would have changed them(damn). I have 217k on the engine and get high 16's low 17's MPG. Would the poppets be considered worn out at that milage?
    I wouldnt use mileage as the indicator for clogged poppets. A balance test should be used to determine the condition of the poppets. You will notice nothing if your poppets are in good condition. However most poppets are far from good condition.

    Here is a must read on for the MPFI conversion.


    http://members.shaw.ca/betterthanyou...g%20Poppet.htm

    Some more
    a cut and paste of the GM decision to use Multec 2 MPFI spider in the LU3 to replace the L35.

    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.

    Some good info on the MULTEC 2 MPFI there.

    peace
    PAul
    97 GMC 2wd RCSB 5.7, s10 2700 footstall, Hooker 24621hkr LT's , 2.5" cats dual 4"pipes exit B4 pass. side tire, custom driveshaft 3.42 G80 FIPK MAF descreen GM/Mercruiser Marine intake manifold 29lb LS2(EV6) injectors Ed Wright PCM(best mod), LT4 KM 14.8@94mph 2.007 4000lbs 122mph

 

 
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