Holley sniper efi 4500

I install a new sniper efi 4500 a few weeks ago ,it runs ok ,but o2 sensor does’nt read , it just switches between heat and unplugged. Spoke to holley and they sent me a new o2 ,but still the same issue. Anyone have any ideas to help me out .

I have been wanting one for my Hemi for a while now......I have no experience with them, but I would check the pins of the plugs and make sure they are all seated...Is it even seeing the sensor and going thru the warm up?

No doesnt read o2 at all stays in open loop

Mopar_Rich to the rescue! FASTMANEFI

Check the pins in the plug reak giuud.....I bet Fastmanefi Rich can even tell you which one to check with a volt meter to see if its even sending power.

I had an open ground on my heated O2 sensor harness. A buddy loaned me his Matco Scanner. It saved me with all the tests you can do on it, but it still took some sleuthing. Mine was going into limp mode after the first minute of running, because the ground was open. I fixed that and it ran normally.

I've been reading on them extensively over the last few months. I suggest you join their FB group and web forum.

After my research; I couldn't pull the trigger. Too much new on my set up to add another variable and the 4500 Sniper is not thoroughly vetted at this point. I went with tried and true Thumper Carbs.

Well, I have a couple of pretty good Thumper carbs on both of my cars. My issue like others, my one car is more of a show poodle and doesn't get run enough and at full temp at idle, its rich.. Lean the idle out, and the 605 won't cold start and idle at all. Our season here is short, and the outside temp swings a lot. The swing is big enough there is not a good way to balance it out. As the temp climbs, the AFR at idle gets worse. So far its in the 12.5ish range at 160 temp and worse when it climbs higher, yet cold, its 13.6, just barely enough to get it to idle at 50-60 degrees out. So I have been wanting one to help me cure cold starts. Been wanting one of the 4500 Snipers since I saw them come out last year....So I am watching this thread to see how this goes.

One thing I can't figure out is the other Holley, Stealth I think it is, comes with an external ECU and costs a bunch more. Not sure why the difference. I just like the 4500 TBI idea for us that need them..

I think the point of the stealth is that is looks like a carb unless you are paying attention. Maybe there isn’t room inside for the ecu? I thought the next step up was the terminator which is double the price but way more powerful. I just put a regular 4150 sniper on my mild 512 it’s awesome. I can get in and drive this thing like a new car the drivability is amazing and the ecu timing control/ hyperspark distributor is a big part of that.

Terminator systems run a Holley HP Ecu. Ecu alone is $1000

Took off the holley efi 4500 and sent it back to holley as they requested, switch back to carb for the first race weekend . I least ill be able to compare both carb and efi now cause i did make some changes to the engine.

Well, hopefully it works out. I am very interested to see how yours works, especially the logging....I miss how efi cold starts and idles. My 1250 is pretty streetable, but it has to be tuned for the weather.

For DW2012, i pulled the sixpack top off my weiand tunnel ram, put on 2 edelbrocks, wired the chokes up and worked like a champ on cold startup. My copilot was joking the whole time that I turned my car into a Chrysler Cordoba.

Hope you get it figured out. We just put the Holley Sniper on my sons Dart as its the 4150 model. Good for like 700 N/A hp and like 1200 boosted hp it says. But its been great so far as its been on the car for about a month now. Its been working good as we have been playing around with some of the settings and put the Sniper dist in it last week so the Sniper system now controls all timing. I like how you can put your own timing curve in it. Good luck to you with yours. Ron