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Thread: Too many variables in play

  1. #1
    Carb and Points! MyTruckBrokeMe's Avatar
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    Too many variables in play

    So...I bought a 1992 Chevy k1500 with an L98 block and 1188113 aluminum heads, factory throttle body, Edelbrock 3704 Performer intake, shorty headers with free flowing 3in exhaust, Comp Cams Dual Energy 203/212 Hydraulic Flat Cam, a 1227747 86ASDU ECM with a Hypertech 120222 PROM, and no idea where to start with the tuning aspects. I bought the truck like this and wasn't expecting everything in the ECM department to be wrong. Injectors spray patterns are uniform and doesn't seem to be having any fuel delivery issues, and I always run 91 octane or better gas. I've already checked and cleaned my grounds. It barely idles above 500 when warm, and surges when I stop. With the timing advance unplugged, it will idle all day long at 0° tdc with no movement, but as soon as it's reconnected, and I advance my timing light to bring the line back to the 0° mark, it's jumping all over the place to about an 8-10° range before and after tdc. I pulled a code 42 (Electronic Spark Timing) but it's a brand new distributor, module, and coil, that I tested and are all working like they should. All sensors and fuses are brand new and functional. So this has led me to believe either the ECM is bad, or it's just delivering the wrong information. I assume it's because of all of the aftermarket parts (especially the cam) combined with a stock tune. I'm way out of my league when it comes to the electronics, but I can and have replaced almost every moving mechanical part in this entire truck so far. Any and all input would be greatly appreciated.
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  2. #2
    Super Moderator dave w's Avatar
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    There are challenges with TBI performance upgrades on a system like you describe. The "Chip" requires re-calibration or tuning for the performance upgrades.

    Several gearhead-efi members have successfully tuned their TBI performance upgrades using TunerPro RT software.

    Myself, and possibly other gearhead-efi member have "Busted the Myth" that a chip can provide optimal performance by using engine modification information only to re-calibrate the chip.

    Myself, and possibly other gearhead-efi members know optimal TBI performance can be achieved with TunerPro RT data logs, see screen shots below.

    There is a steep learning curve to TunerPro RT, but will worth the time and effort.

    There is also the option to upgrade the TBI computer your using to a Dynamic EFI computer (https://www.dynamicefi.com/EBL_Flash.php) which has an "Auto Tuning feature".

    The Dynamic EFI computer also uses TunerPro RT.

    dave w
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  3. #3
    Fuel Injected!
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    I have an EBL flash for sale, PM me if you're interested. it made my stock '89 caprice run better with a provided base calibration before i even started messing with it.

  4. #4
    Carb and Points! MyTruckBrokeMe's Avatar
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    Yeah, I can't afford anything in that range anytime in the foreseeable future. I've spent every extra dime i've had on this truck over the past year

  5. #5
    Super Moderator dave w's Avatar
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    TunerPro RT is freeware, with a suggested $39 donation. Most TurnerPro RT users send a donation after getting things figured out.

    The cable that connects the laptop running TunerPro RT to the ALDL diagnostic connector is affordable, most are priced at less than $60. http://aldlcable.com/products/aldlobd1u.asp

    dave w

  6. #6
    Fuel Injected!
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    A cheaper/crappier looking ALDL cable that works with tunerpro http://www.gearhead-efi.com/Fuel-Inj...-Cable-for-TBI

  7. #7
    Fuel Injected!
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    If you want to go cheap and slow then start by getting a cable so you can connect a laptop and get Tunerpro reading the truck. At least then you can start learning what the sensor data looks like so you can both confirm everything is working and know what tuning issues the truck has.

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