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Thread: 1990 454SS - TBI 220 to Sniper conversion.

  1. #1

    Default 1990 454SS - TBI 220 to Sniper conversion.

    Hi Everyone. I'm new to the forum, so hello in advance! I have a 1990 454SS equipped with a stock throttle body. Once the weather warms up, I'll be replacing the TBI with a Sniper system. One of my concerns is how to dismantle the wiring harness that the current ECU is using. I'd like to cleanup the engine bay as best as possible. Has anyone done this swap before and if so, is there anything you learned while going through the process that would help me? I'd imagine there are some processes that will still rely on the ECU? Did the 'check engine light' go on and how did you turn it off? Pull the bulb from the instrument panel? Thanks! Brian

  2. #2

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    I have a hunch it's going to be much more complicated than what you're thinking. You'll probably need to buy a TBI delete engine harness if anyone makes one. Typically it isn't very easy to hack up a late model factory harness and still have the vehicle run. If you have a check engine light then that's probably a OBD-I vehicle which makes cutting the factory harness apart really tricky. Good luck is all I have for advice.

  3. #3
    Join Date
    Dec 2009
    Location
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    My '92 Ford Mustang GT was an OBD-1 vehicle, and I don't have a Check Engine light after converting to Holley EFI. No (OEM) ECU, no Check Engine light.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 11.8:1 comp, TFS R-Series FTI ported intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 MT tires.

  4. #4

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    I think it's very vehicle dependent. I've talked to people who have tried to modify OBD harnesses and ended up costing themselves a ton of time and money. On some Chrysler cars the factory ECU controls the windows. If you unhook the factory ECU you can't operate the windows. I know a guy with a Subaru who tried to modify the ECU and ended up with a dead car. He had to buy a new factory computer and pay the dealer to reflash it before he could drive his car. I think the Ford stuff is the easiest to mess with, other brands are almost impossible to work with. I don't know anything about the Chevy 454SS so the OP is going to have to do some research.

  5. #5
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    24,063

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    OBD-1 (early '90s) only controlled the engine.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 11.8:1 comp, TFS R-Series FTI ported intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 MT tires.

  6. #6

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    If it was anything like the 1990 3500 with a 454 I used to have, then you'll just need to study the wiring diagram.

    You'll need the 700R4 cable bracket. EFI fuel pump for 60 psi, which can be done with an in-tank pump. Engine coolant will be displayed through the handheld. Go with a HyperSpark distributor and CDI box to maximize efficiency and performance. A/C can be wired to the Sniper and the Check Engine Light will be up to the OP to remove or not.

  7. #7

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    Just curious, why go from OEM EFI to Sniper?

  8. #8

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    OEM 2 barrel TBI sucks. I did it in my old 1990 K2500 with a 350. Sniper kicks its butt. I agree with using HyperSpark and the CD ignition box. The stock distributor is controlled by the stock computer. I couldn't be happier with my engine management system. Go with electric fans too.

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