Need Help with Converting to Holley Sniper EFI 1999 K2500 7.4

[amrush2112]

I am considering converting to an aftermarket EFI such as the Holley Sniper Terminator or the Edelbrock Pro Flo 4. Has anyone done either of these conversions? Mine has the 4L80E and I would like to maintain all factory gauges.

My questions are:
1. Do I need to maintain factory computer to run trans and 4x4 switching on dash
2. Will there be any issues with the computer not reading some of the sensors and have check engine light issues?

My plans are to go to aftermarket AFR heads, aftermarket intake intake and distributor to run the timing control, and better hydraulic roller camshaft to match the heads and intake setup. I also plan on putting full long tube headers and aftermarket exhaust. I live in a non-emissions county and since its 23 years old anyways I won't have any worries on inspections.

Any feedback would be greatly appreciated!

Thanks!

 

[amrush2112]

I guess with 5 months and no response I guess I have my answer. Well if anyone sees this that has done this please post back.

 

[618 Syndicate]

@Erik the Awful
@Wh4t3v3rs

 

[Erik the Awful]

Apologies, I must have missed this five months ago. Honestly, I don't know what it takes to get a Sniper running on a Vortec/4L80E truck. I have mine running fantastically on a TBI/700R4 truck. The computer is still there, controlling the TCC lockup, but otherwise doing nothing except shining that "Service Engine Soon" light. I do plan on moving the engine into my C3500 and mating it to a 4L80E, but I'll be using a stand-alone transmission controller at that point.

The Holley Sniper and Terminator are two separate product lines, but if you're trying mate it to the factory wiring and also control the transmission you want to consider the Terminator X Max. If you do go with a Sniper be sure and get the extended throttle linkage. Note that you can't have any exhaust or vacuum leaks or the system won't tune right. The Sniper will never be a "toss your keys to a friend" setup. When you turn the key on you have to wait two or three seconds to fire the engine or you'll be cranking several seconds while the computer boots up.

Honestly, unless you're aiming for 500+ horsepower, you might want to stick with tuning your Vortec setup. I have a pretty lumpy cam, and the upgraded spider injection handled it just fine.

 

[TacosnBeer]

Amen to Erik's final point... mixing the computer with aftermarket is painful... I have been both directions with 2 different trucks now (removed the EFI for Carb and now with an LSX/4L80e) and IT IS NOT FUN at all. Nothing but problems with one thing or another... stand alone for some things is the way to go unless it needs to feed the computer which most things on the upper OBS years. The 88-93s are much easier because everything is run through the computer.

 

[yevgenievich]

Ecu/tcm of choice will need to accept a 4lo signal. AC controls will either need to change for stand alone or have the new ecu accept them.

 

[Wh4t3v3rs]

I'm kind of a Holley guy, and I have the Term x I'm using for my LS swap. Inputs and outputs is whats gonna the problem when you try to piggyback on the oem ecu. Be prepared to purchase the expansion module unless you have the coin for the Dominator.
As far as the Sniper system, I have to agree with Eric, but wanna add on Electrical interference can be a BIG problem. At Holley training they stressed FOLLOW THE INSTRUCTIONS to the T!!!!

 

[RDF1]

I'd steer clear of the sniper units. I've only seen a few of them last. Most have injector issues, ECU issues, and several of them just crap out and have to be sent back for repair.

 

[amrush2112]

This is great feedback! I didn't want to come off sounding like an A$# so apologies if it did. My first thought was to go the 0411 swap and put a tune on it. My 454 has only 136k miles and is bone stock. It was a California truck and has full smog. My intent is to remover all the smog stuff (no inspection in Texas where I live so clear on that - in about a year and a half it would be exempt anyways). Eventually would plan to change the cam to a Comp HR grind and install full length headers with 02 and wide band installed on both banks (not sure if its both but would assume so). I don't have any plans on making it a 500 hp monster or anything but just to improve where it is **** (above 4200). I am pretty up on the 0411 swap and think based on the feedback here that it would be the best route to go and save $$$.

 

[amrush2112]

I am also building a 65 GTO street/strip car that will be getting the Holley Dominator set up and a S480 single Turbo. The more I save on the Burban would go to funding the GTO and happy times. Lol!