I’ve been running a Holley 4Di fuel injection in my Corvette for over 15 years. It worked great, but I was looking forward to a self-learning, always perfect air fuel ratio, Holley Sniper to come out. I saw it at SEMA in 2015. I placed my order as soon as I could and waited, and waited, and waited. When I finally got my Sniper a year later, I pulled out my Holley 4Di. I had forgotten how much wiring I had to do to install it. The Sniper is way simpler, and the ECU is part of the throttle body. Installation was simple and very straight forward, since I already had a fuel injection fuel pump and fuel system. There is still plenty of wires, but I hid it all under my windshield wiper trough cover. The sniper is 1” taller, so I had to switch to a lower profile Specter air hat. The only problem that had me, and some Holley technicians, scratching their head was not getting a nice low 900 rpm idle. The idle would not settle below 1500 rpm, and would usually run at about 2000rpm. I finally figured it out. The secondaries were not closing completely. The secondaries have their own return spring, and it’s much weaker than the Primary return spring. Using two pairs of needle nose plyers, I put another turn on the return spring. Holley will have to strengthen that spring in the future. Another disappointment, my old fi controlled the ignition timing using my computer controlled HEI. The Sniper requires either a MSD or Holley distributer to control timing. So I returned to my old school weight and vacuum controlled dizzy.
I have yet to put a long drive on it, but driving close to home, it works good. Immediate throttle response. Not much difference since I already had a fuel injection. The handheld monitor is kind of fun. It has lots of information available to display.

 

That sucks that you couldn't keep timing control. I do know of a few people who have used the newer small capped ECU controlled HEI distributors with their EFI setups, although it was with Fitech setup. I'm sure if it will work with those, it would, or at least should, work with these.

Mine was running very well just using fuel control, but now that I finally added timing control, it's ridiculously smooth accelerating, and smoother idle due to the spark control doing it's job.

You're the 2nd person I know of with the sticking idle.

I had the complete opposite issue. My secondaries were sticking in their bores, making easy drive away from a stop near impossible...I tweaked the linkage's secondary stop just enough to not let the secondary butterflies over close and stick.

How close are the coolant temperature readings between the Sniper and your car's gauge?

A few of us, probably more, have had to replace their CTS with an aftermarket one due to it reading too cold and not staying in "Learn Mode".

 

I forgot to mention that, thanks. My Sniper temp reads way high. Almost 40 degrees higher than my Autometer, which I know is right. Acording to the Sniper handheld, I am overheating and should pull over. This is probably affecting my tune.
Another nice feature of the Sniper, I am using it to turn my fans on and off. The Holley plug and play dizzy to control timing is half again as expensive as the fuel injection unit. I'll stick with this old skool dizzy. But when I added the vacuum canister, I had to reclock the dizzy to this crazy angle so that the vacuum would clear everything.

 

Probably true that the tune is affected by false high temp reading.
FWIW, I used a 2002 Chevy Express 2500 w/4.3 litre as my application for a new sensor. It now is dead on my Autometer gauge's reading.

I actually tried ordering the Holley Dual Sync distributor well over a month ago, and finally gave up. It's still showing a month from now as "expected date"...

I used a basic MSD Pro Billet, 260 bucks or so, and just locked it out, as per the instructions. It's a plug & play after being locked out.

 

So....did the sensor go dead? Are you going to try something else?

Jebby

 

It worked correctly, for a few days, tops...Then was reading 15-20 degrees too low, which made the Sniper's handheld reading hover in the 157-160 range, so it constantly was in and out of learn mode, which is no good for any type of accurate info...

I bought a Standard Products TX3T sensor locally, for under 10 bucks, and now it matches perfectly with my Autometer, 177-180 degrees...for the cost, it wasn't worth the wait on the tech line phone number to me.

Any of these will work:

http://www.rockauto.com/en/catalog/c...+/+sensor,4748

 

BeeJay can you use the MSD pro billet replacement for TBI/TPI cars?

 

TX3T.....bookmarked....thanks

Jebby

 

Yes.

 

Okay other than that how is your thoughts on the new mono spring. I'm just a hard spring junkie