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So in my hunt to smooth things out with my sniper I came across many people who were unhappy with the unruly throttle response. SO unruly, for me I needed to keep my foot wedged into the trans tunnel and roll my foot back into the go go pedal or else you would snap your neck back taking off so quick.

Snipers are sold and sent with a 1 : 1 connection between all four ports. This causes much too much HP for normal street driving. They make a progressive rod that gives you 37 to 40 percent of primaries before secondary open which is the way normal carbs are sent out. Not sure why snipers are sent out this way?

Of course a small piece of bent rod is 20 bucks. I may try to make one this weekend. If it does not go well then I can buy something that should have some in the box as a option.

Can you temporarily disable 2 pots for testing?

Should be able to. I can program sniper for progressive and tell it secondaries don't come in till 100 percent. That will give me a 2b for all tense and purposes.

I would try that as a test.

Keep us informed.
If duty cycle could be set for 70%+ for secondaries?
I am currently wiring in for Sniper on a C4 350, and probably don't expect to get it on the road til spring, so a bit of knowledge before then will be greatly appreciated.

I am standing on the shoulders of others solving my problems. Don't mind if you stand on mine.

Got home from work and decided to see if I could disable my secondaries. Took 1 to 1 linkage off and told sniper not to fuel until 90 percent tps.

Took for a drive. Wasn't happy at first but it smoothed out nicely. Easy throttle input, responsive like one would think.

I just figured out what I will do when my.kids drive the truck a few years from.now.

So it sounds like it has been overfueling with the 4 barrels connected, too much throttle body?

You need to switch out to a “progressive secondary linkage”. Holley makes two different ones. On my 454 with a Holley Terminator X Max Stealth with a 4150 throttle body I ran into issues where the secondaries would stick when coming down to an idle. I switched out to the adjustable linkage and then and now they open at approximately 51% tps and close much better.
Once you install it you go into the software and turn on progressive secondaries and set it to the TPS where they open.

Progressive linkage kit

It is looking that way, but when I tested with a home built and programed accordingly it fell all.over itself? I think I haventhe same issue of seondariws.sticking at times.

With secondaries out of equation, and programed not to co e in until 90 percent I feel more.rpughness and my afr is all over the place while alleviating at 25 to 30 percent tps.

I haven't purchased Holley linkage yet, but I have been driving around on 2 injectors with second two programed out to 90 percent.

I has gotten better, and it is a joy to drive as long as you don't give it too much throttle. I have noticed the following.

1. Anything over 30 percent TPS it surges like a lean condition, but the AFR bounces rich to normal.
2. Coming down a hill with no TPS. AFR used to go high lean like 25 to 30 to 1. Now with only two operating it stays between 13 and 15 to 1.

I am surely scratching my head and making only ne change at a time as I go. If I can get the smooth drivability of just two, but not have issues when 4 open I will be in heaven.

Did you try adjusting the target AFRs like I suggested in your other thread?

All of this reads to me like you have too much injector. That is why disabling two of them is helping.

What is your pulse width/pwm during decel?

Sorry. Yes. target afr's are set. And it adjust accordingly. I was finally able to get ahold of Holley and they say no on the progressive linkage. They have a throttle extender which is what they want me to use?

Now I have to read about it.

Did they give a rationale for the throttle extender? It seems like that would make it less "touchy" by giving you more pedal travel, but is that the problem you are having?

Where is your O2 sensor? And what intake are you running?

I am wondering if you are getting some weird effect from the location of your two injectors relative to the routing in your intake?

The measured AFR is an average across whichever cylinders are joined before the O2 sensor. You could be getting some unexpected results from that, maybe?

Played around with it today. I made a extender based on measurements from holley. I was also wondering if they run all 4 injectors together for even fuel distribution?

Installed extender
Put 1 to 1 linkage back in
Programed it back to normal.

The extender definitely solved the roll in issue. Much smoother, but it did nothing to solve the secondaries from sticking open. I still had to knock the throttle to bring it back to 0 tps almost every time. I lubed all springs and linkage joints and it did not improve.

Afr returned to normal.

It does not bind at all with engine not running. I can monitor tps and bring back slow and it always returns to 0 or 1. With engine running it wants to stay at 6 to 8 percent. Knock it like an old choke and it returns to 0 or 1.

You could take the spring off and add one more turn to it to help close the secondaries at idle. Ive seen good results with that too.

It sounds like high vacuum at idle or deceleration is cocking the secondary throttle blades and causing them to bind in the bores. I would ask Holy to replace the throttle body.

I was looking at the secondary spring wondering if that was possible. I'll be bummed if I need to replace the unit.

I do think I am closing in on it. Not ready to give up yet.

Wound the secondary spring around one more time with no results. Have inquiry in with Holley again.

Ferris Bueller: I’ve got a friend with a Sniper on a 350 who recently found his irregular idle speed to be caused by the throttle cable wearing into the cable housing and binding. Been following your thread….just wanted to put this out there. His discovery would not necessarily have to be related to only a Sniper for that matter.
Good luck, Dave

Similar to Dave's comment, I fought and fought and fought with the idle on my sniper until I replaced the throttle cable and all of those issues just went away.

I was thinking your post was mainly about the secondaries, but it sounds like you are having similar idle problems.

As a test, unhook the throttle cable and rev it up by hand, then just let go. If it still doesn't go to zero TPS, then you have a problem in the sniper. If that does fix it, try re-routing/replacing the throttle cable.

If you enlarge the picture I sent, above, you’ll see how the cable is off center in the cable housing….

I have rod linkage with things very straight and lubed.

With engine off it will return to 0 every time even if I bring it back super slow.

With engine running it will go to 0 if it snaps back, but if brought back slowly it will remain at 3 to 8 percent TPS. I am positive the problem is sniper now. Tech is calling me supposedly today.

This is the last piece of the puzzle with it.

I can almost guarantee the progressive linkage will solve this for you.

It didn't. It actually send the sniper into a fit cause the secondaries stayed open and they were not fueling.

So you were getting extra air through them, but no extra fuel?

That would cause some problems for sure.

If they weren’t fueling that’s a tuning issue. There’s plenty of documented issues with the secondary’s sticking. Some people can add a wrap on on the spring and that solves it. Others loosen the screws on the blades and recenter them. I ended up buying the adjustable progressive linkage and have no issues now.

Yes. When you install the progressive linkage you find the percent of TPS where the secondary's open and program that in. So at 3 5 or 20 percent the secondary's do not fuel at all unless its a 1 to 1 ratio.

When the secondary's hang it allows additional air through which confuses the sniper.

I know the blades are centered. I have added the wrap on the spring. I think the solution for smooth drivability is a combination of the extended and progressive linkages. I will have some programing to do once I iron out the blade sticking issue.

what I will do?

You have a new job: fixing your son's toy.

Curious: did you ever in the R&D say "the whole EFI thing was a mistake"?

Not in my case. Even with the growing pains on the Sniper, it has been a whole lot better than any carb I have had the (mis)fortune to deal with.

I have to agree right now too. Once iron out it is going to be a dream. All ready is when I hit the key at any temp in the morning and it fires, idles high for a few seconds, and then settles down.

So in an attempt to try something different I added the old carb spring to the sniper, drilled a small hole in the intake and attached.

Now the TPS always goes back to a min of 1 and most of the time 0, but the throttle is stiffer than I like.

Worked great for half a day, then the idle started going up with the TPS and IAC at 0. Sometimes the IAC will be at 20 with a high idle and TPS at 0. I have to give the throttle a big stomp and it comes back to a nice idle.

That is indicative of it not thinking you are at idle. Try setting your IAC park position at zero instead of 20.

That is what fixed that issue for me.

Well.........

I have initiated a replacement under warrantee. The IAC goes bonkers anytime it wants to. I can't get the TPS and IAC to zero with all four barrels unless I smash the gas every time. Now the fan does as it pleases and does not conform to programed on/off.

I am hoping a new one will fix all of this.

The ol' Carter YF is looking better and better.

Go back to the Q-Jet.

The best way to "fix" a sniper is to leave it on a shelf in the shop and run a carburetor!
Jerry

We will see how Holley handles the warranty, but my Sniper works a heck of a lot better than any carb I have had the misfortune to deal with.

Set the AFR once, walk away, and drive.

No adjusting for temperature or altitude. It just works.

Spoke with Blue Print yesterday. They had a few questions to confirm what I have tried to work through and immediately made the call to replace it. Problem is sniper does not make the 1 anymore, only the 2. So they are sending me the updated sniper 2 with needed accessories to make it work.

I didn't realize you got the Sniper from Blueprint with the engine.

Sounds like they are taking care of you.

Do you know yet if you have to change any wiring for the second gen unit?