TBI to Terminator

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Swill2

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Hey everyone, first post on here. I’ve been building a full custom 1990 K1500 SCSB, 4 Link SAS on coilovers and 40’s. This has been a 3 year long project and finally coming down to the nitty gritty. I’ve purchased a HT383 from GM and am going with a 4L80 trans along with Holley terminator for fuel injection and to control the transmission. My biggest question is how to keep what I need out of the computer like climate control cruise control and other things I’m sure I’m forgetting without the factory computer seeing that the engine is running. Would I need to double up/piggyback certain sensors to trick the computer into thinking it’s still controlling the engine? Biggest concern is getting this thing registered in NC and showing up to the inspection station with a check engine. Let me know what y’all have done and let me know if you’re interested in the build! Thanks!
 

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Drunkcanuk

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Welcome from Alberta Canada.
That's a dang fine looking project you have going on.
I'll speak for a lot of people here and say get a LOT more pics and write-ups of what you have been up to for the last 3 years!!! Lol
There are some smart people on here, hopefully someone will be able to help you with the switch to the Holley setup.
I believe "Eric the car guy" on YouTube used a Holley on his truck.
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Take a look through the playlist for the engine section. Sure he blabbed at length about how he integrated it. Been a few years since I watched.
 

L31MaxExpress

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It will never pass a visual inspection with an aftermarket EFI system.

As for a "Check Engine" light, as long as they are not scanning the stock ECM, that can be duplicated by tying an oil pressure switch to a normally closed relay circuit. When the engine is not running, relay grounds the check engine light bulb, illuminating it, when you start the engine, the oil pressure switch grounds the relay which then opens the circuit, which then disables the ground on the bulb. Some states require a check engine light that is illuminated during bulb test and turns off with a running engine.
 

Swill2

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Thanks everyone for the welcomes and thanks to Drunkcanuk for the video I’ll definitely watch through that.

Probably not the right thread for this but here we go! To make a long story long purchased this truck 10 years ago off Craigslist for 2k with about 180k mi. Factory “4x4 Sport” w/ 5.7 TBI. Around 260k mi started throwing 700r4’s at it left and right. After the 3rd “performance” transmission from PATC failed I decided to park it and get something newer. Fast forward to 3 years ago decided it was time to tear into it and bring it back with some changes. Stripped the factory drivetrain, suspension and all of the factory crossmembers out of it. Stripped the frame down to bare metal and boxed the frame with 3/16” plate. I purchased a 20’ stick of 2-1/2” SCH 80 seamless pipe and pierced the frame for new crossmembers.

Axles I got for a steal from a local scrap yard - D50 high pinion and sterling 10.5. Stripped those down to nothing, added trusses from Artec, welded the tubes to the center section, and purchased a 4 link kit from Barnes. Went with 4.56 R&P from Yukon, ARB locker front and rear, Yukon manual locking hubs, 4340 stub outer shafts in the front, upper ball joint eliminators, spicer lower ball joints and u-joints, and timken hubs. Went with a high steer kit from Barnes and a PSC hydro assist through Offroad design as they offer the 8.5” stroke ram that needed for stop to stop steer angle.

Front suspension is a 3 link with panhard bar, 12” fox 2.5 coilovers with DSC. Rear suspension is a semi triangulated 4 link with 16” fox 2.5 coil overs. Sway bars front and rear from TK Racing (excellent customer service might I add).

For the drivetrain got a HT383 from my local Chevy dealer, through in some 1.6 roller rockers, melling oil pump, deep sump pan with trap door, air gap dual plane intake and some better looking valve covers. Ended up having to go with shorty headers due to the upper link on the passenger side and driveshaft on the drivers side. Having a local guy that builds transmissions for drag cars go through a 4L80 I pulled out of a ‘93 k3500. I rebuilt the NP241 transfer case that came with the transmission with all new bearings, chain and a slip yoke eliminator. Lastly got some super strong looking driveshafts from Adams Driveshaft

Some of the misc. items - purchased a pre-bent cage from S&W and did a couple mods on it as far as the door bars, main hoop bracing and kickers. Brakes are bolt on from power stop for the Super Doodie that the axles came out of, hydro boost will be courtesy of a 3500 express van, still working on getting the correct pedal pushrod geometry on that front. Replaced/rebuilt all of the a/c and heater parts behind the dash since it won’t be coming out anytime soon lol. I purchased some Glidden super max ultimate flex master spray paint from Home Depot to re-spray all of the factory interior plastics and turned out really good IMO considering $5 a can Vs. $20+ a can for the perfect match paint. Installed boom mat on the entire interior as well. Got a 40 gallon fuel safe fuel cell that’s going to mount at the front of the bed.

Some of the struggles I’ve had with this build was the steering box location and angle since I had to push the axle out to get the 40’s to clear the cab at full articulation. Also because the front axle pushed out I had to cut quite a bit out of the only remaining cross member - front lower control arm cross member.

This has been a very fun and frustrating build haha but most of all COSTLY. My original budget of $15-20k went out the door rapidly with the increased cost of aftermarket parts in the recent years. Sorry for the long post, hopefully it helps some of y’all move forward with your own projects!
 

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Swill2

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It will never pass a visual inspection with an aftermarket EFI system.

As for a "Check Engine" light, as long as they are not scanning the stock ECM, that can be duplicated by tying an oil pressure switch to a normally closed relay circuit. When the engine is not running, relay grounds the check engine light bulb, illuminating it, when you start the engine, the oil pressure switch grounds the relay which then opens the circuit, which then disables the ground on the bulb. Some states require a check engine light that is illuminated during bulb test and turns off with a running engine.
Should I assume this would still be true with the visual inspection even though the truck will still technically have TBI.
 

Swill2

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here's some more of some early work on the back end
 

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