Home Forums Gear Hunting Trucks and Four-Wheel Drives Holly Sniper EFI

Looking for pros / cons.

Have a 1979 CJ-5 with 258 straight 6, and am thinking about doing an upgrade.

Anyone care to help shorten my learning curve?

Run Forrest Run!!!

That bad huh?

that's what i've heard about aftermarket EFI in general... or more specifically FI Tech & Holley Sniper... ECM failures pretty regular... other issues too, but i didn't keep track of it...

I went with the Edelbrock Pro-Flo 4 on my 427 Windsor and it has been flawless. They do not offer the same for your engine and I would agree with the above. I had a 79 CJ-5 with the 258 six and added a Clifford Research intake, a 490 CFM 4 barrel Holley and Clifford headers and the package made a difference.

maybe look into retrofitting OEM FI from a later model Jeep 6 ?, thad' be the cats ass!... otherwise stick with a well tuned carb, or a multi carb setup for better fuel distribution... IMO

Swap in a 360 AMC!

Any chance to find a complete EFI 4.0L I6? The whole setup might cost less and be less headache.

Great engine - stopped making them 8 years ago. Probably a bajillion of them out there tho - need to find one low miles with complete harness and ECU too and then hold onto hope that support for that ECU lasts/gets support. Which is really no different than purchasing an aftermarket FMS from Holley or whatever. Not that Holley goes under but CARB/EPA could decide the tunes aren't good enough and hit them hard at a political whim.

I'd probably check a local salvage yard, the "good" one's have a database of what they've got and what a bunch of others have.

Or, watch Marketplace and Craigslist for a whole vehicle cheap. Watch until you find one that runs well or is so cheap you can afford a re-build of the motor. Pull the motor, ECU, and any other parts you like, salvage-yard the rest

One can always go the Weber route.

The Sniper II is better.

Thanks for all the constructive comments so far, gives me some more to contemplate.

My main frustration with the current carburetion is having to tweak on it depending on whether I’m operating at near sea level, versus 5k or so elevation.

I put a Webber on a 258 & was surprised at the dependability & performance gain. I DID NOT try it on any off angle driving so not sure how they do there.

A couple of years ago I converted my carbureted Cobra replica v8 to a Holley Sniper EFI system. What a difference in performance, wintertime starts, fuel mileage, etc. The setup is easy, and the learning mode adjusts your system to altitude, driving habits, etc. I bought the returnless system, a bit simpler than the return setup. Without the mechanical fuel pump on my engine, vapor locks have been eliminated entirely. It now has an electric fuel pump in the fuel tank- on cold startups, just turn the key on, let the pump prime itself up for a few seconds, and then instant start. If you drive in varying altitudes, EFI is definitely the way to go. This was my first experience with a throttle body EFI, and I am totally satisfied with it!

Most of the fuel injected CJ owners I know are engine swapped. I'm currently looking to go that route with my 84 CJ7. The Holley Sniper II would be the cheaper route, but I need a new block. I have a complete 4.0l engine on a stand as well, and would install it or a 258/4.2l with an Clifford Performance kit for simplicity. However, I'd love an LS swap as that would greatly improve drive ability over the I6 motors. It is just way more involved than I have time for, and I'd probably pay a shop to do it. A 4.0l swap with MPFI would definitely fuel your engine better than any TBI on your current 258.

We tried an aftermarket (Howell) TBI injection with 4.0l head conversion on my daughter's 88 YJ. It was a fairly easy install, but had a lot of issues with it. Howell is kind of a PITA for technical support. The Jeep started a lot better with the TBI, but we could never the idle set correctly. It would work correctly for a couple days to a week, and then it would be idling constantly above 1200 rpms and dieseling at shutdown. The Howell kit was also very old tech TBI and not really easy to tune, all you can really do is throw parts at it.

Because of the TBI issues we started to do get the parts for a 4.0 swap. I picked up a complete used motor and auto transmission (packaged deal). I was able to sell off the transmission for $300 and left us in the engine for $100. I never did locate the AX15 manual transmission, correct ECM, and wiring harness (factory EFI harness 1991 YJ and up) before she lost interest in the project (job and boyfriend).

If you do a 4.0l swap into a CJ you'll have to relocate cam sensor on harmonic balancer instead of in the bell housing. Or you'll need to change your flex plate and properly install the sensor in your current bellhousing. HESCO used to sell cam sensor relocation kits, and you might give them a call. Since I had planned to upgrade the transmission from a T5 to the AX15 I wasn't going to need the relocation kit or modified bellhousing.

My daughter decided she wanted something more reliable after graduation, both the Jeep and boyfriend. Kicked him to the curb and bought an 02 Honda Civic, then sold off the YJ for more money than she originally bought it for. I imagine she'll have another Jeep one day, she keeps sending me marketplace ads for used TJ Wranglers asking me my opinion?

i am more than likely going to go with the Holley Sniper II on my Dauntless odd fire 6. I will have to set up a crank sensor, but that is an easy set up. Would have to do that with any EFI system out there.