Build 1985 FJ60 Gets a Holley Sniper EFI Setup

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Anyone here experience a dip in RPM when coming to a stop in gear? It seems to want to drop out, and does sometimes. idle is fine, come to halt braking is all good, but leave it in gear and lug it down, the Rpm drops, the AF spikes etc. the IAC doesn't catch it well. Ive incrementally tinkered with most parameters on the little screen, and nothing really seems to affect it. (iac is around 3-7% warmed up). best i can do is run the idle high at 850 and that lessens the impact, but its still there. shame too, because otherwise i can get this running nice with a 650 idle.

It sems like it goes to open loop, then back to closed, and somewhere in the transition back and forth the fuel map loses contact with reality and it wakes up in a free fall and tries to catch it.

if so, what was your fix?
 
Yes. Mine behaves after it warms up past the 160° threshold. I set idle to 750. But until then, when coming to a stop, AFR goes to 22:1 (lean) then it tries to catch up by dumping fuel in. The slightest blip of the the throttle saves it from stalling. It's annoying for sure.
 
On the older efi systems like Bosch Lh 2.2 and Bosch kjet (aka CIS) they had little diaphragms or springs on the throttle plates to slow down the throttle plate as it neared full closure. This was an old school method for helping to eliminate the rpm dip you are referring to. Basically the air flow changed too quickly on some of those older systems that the fuel mix didn’t keep up and you got that stutter or rpm dip and surge. Might be something similar going on with the sniper.
 
And as an aside I briefly thought about trying to install Kjet onto a 2f only because I have all the parts handy and aside from a hi pressure fuel pump it’s an entirely mechanical system. Amazingly robust…simple in that it’s entirely based on fuel pressure. It’s still something I might try at some point just for the hell of it.
 
I’ve got one doing this. In the advanced fuel setting I’ve been trying to increase the delay time to idle. So far it’s not working.

Runs pefect but dies after hot when you coast to a stop after a longer drive.

Crazy thing to add to this.

It does this with two separate snipers so I’m having a hard time blaming the Sniper.

It’s super hot here right now but I’m going to get up early tomorrow and do some data logs and see what Holley says.
 
I’m considering the sniper. I have a question but I can’t find a straight answer after reading through a lot of this thread. Can this set up pass emissions? It seems like it would improve emissions over the carb setup but I’m unclear on how all the smog equipment would work on the sniper. Ideally I’d like to desmog and install headers, but the timing of this swap and my current situation are informing my decision here.

My tags are expired, I’m failing smog and I can’t figure it out, though I think I have a crack in the bottom of my carb. I’m moving to a non emissions state in a few months but I’m unsure if I should install the sniper, get my tags, and drive or should I wait and put the 60 on a dolly and tow it?
Either way I want the sniper set up. I hate losing power when I’m climbing in altitude.
 
wngrog said:
I’ve got one doing this. In the advanced fuel setting I’ve been trying to increase the delay time to idle. So far it’s not working.

Runs pefect but dies after hot when you coast to a stop after a longer drive.

Crazy thing to add to this.

It does this with two separate snipers so I’m having a hard time blaming the Sniper.

It’s super hot here right now but I’m going to get up early tomorrow and do some data logs and see what Holley says.
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Can you adjust the mixture at this throttle point? Maybe try leaning it out if you can….I’d guess that when the throttle closes it’s on the rich side due to loss of incoming air.
 
cps432 said:
I’m considering the sniper. I have a question but I can’t find a straight answer after reading through a lot of this thread. Can this set up pass emissions? It seems like it would improve emissions over the carb setup but I’m unclear on how all the smog equipment would work on the sniper. Ideally I’d like to desmog and install headers, but the timing of this swap and my current situation are informing my decision here.

My tags are expired, I’m failing smog and I can’t figure it out, though I think I have a crack in the bottom of my carb. I’m moving to a non emissions state in a few months but I’m unsure if I should install the sniper, get my tags, and drive or should I wait and put the 60 on a dolly and tow it?
Either way I want the sniper set up. I hate losing power when I’m climbing in altitude.
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Well…you would likely fail the visual check if that is a component of your test. If all you have to pass is a sniff test then you should be able to tune for that.
 
cps432 said:
I’m considering the sniper. I have a question but I can’t find a straight answer after reading through a lot of this thread. Can this set up pass emissions? It seems like it would improve emissions over the carb setup but I’m unclear on how all the smog equipment would work on the sniper. Ideally I’d like to desmog and install headers, but the timing of this swap and my current situation are informing my decision here.

My tags are expired, I’m failing smog and I can’t figure it out, though I think I have a crack in the bottom of my carb. I’m moving to a non emissions state in a few months but I’m unsure if I should install the sniper, get my tags, and drive or should I wait and put the 60 on a dolly and tow it?
Either way I want the sniper set up. I hate losing power when I’m climbing in altitude.
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It’s not EPa/CARB approved but if you only have a sniff test then it absolutely will pass. If it’s a visual where they look for the smog equipment it won’t
 
Seth S said:
Can you adjust the mixture at this throttle point? Maybe try leaning it out if you can….I’d guess that when the throttle closes it’s on the rich side due to loss of incoming air.
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There are some good discussions on the Holley forum about adding a separate AFI table during this ramp up. That’s above my head. I’ve got 10-12 snipers out there I own or have worked on and to date I’ve never had to do anything like this. Hell, most of them are running stock settings.

This one literally came to me for this issue. I tossed parts at it because no one could figure out the stall and son of a bitch if the new setup doesn’t do the same thing.
 
wngrog said:
There are some good discussions on the Holley forum about adding a separate AFI table during this ramp up. That’s above my head. I’ve got 10-12 snipers out there I own or have worked on and to date I’ve never had to do anything like this. Hell, most of them are running stock settings.

This one literally came to me for this issue. I tossed parts at it because no one could figure out the stall and son of a bitch if the new setup doesn’t do the same thing.
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Assuming all the basics are in spec....valve clearance, plugs, cap, rotor, wires, filter etc....I wonder if an engine with lower compression is more likely to suffer a problem like this?
 
Seth S said:
Can you adjust the mixture at this throttle point? Maybe try leaning it out if you can….I’d guess that when the throttle closes it’s on the rich side due to loss of incoming air.
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Engine braking, or coasting in gear causes it to do that. Throttle closes, IAC opens to burn gas still in system, vacuum is at maximum (?) System reads lean, adds gas while rpm slows, (less vac)... overly rich AF going through the system about the time clutch is depressed, rpm continues to fall, it may catch or may stall.

Thinking aloud to make sure I'm getting this right and we are all on the same page.
I wonder what would happen if vac advance was switched from ported to constant?
 
It's interesting that mine has this issue before it's warmed up and @wngrog has this when at operating temperature. Nolan does yours do this cold as well?
 
In the half dozen or so Snipers that I've set up or worked on, not a single one operates like the factory EFI that Holley markets it to be -- even after they've been given the time to learn. I know of three with this dip. One straight up dies until it hits 160F. Another dips and also has a stumble that pops up around 2krpm and 60% throttle that can only be cleared by lifting the throttle. Talked to Holley, and they see these things, have tossed several "fixes" at them, sent me a global files...still does it. Owner is understandably pissed.

It's a very good product, but they missed the last 5% of execution. Pretty hard to hit that 5% when there are so many variables to try and account for.
 
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MoaByte said:
It's interesting that mine has this issue before it's warmed up and @wngrog has this when at operating temperature. Nolan does yours do this cold as well?
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Nope. Does not do it when you do quick stop and go either. Has to be over a mile at cruise
 
MoaByte said:
I had a bog at about 60%-100% throttle.. moving the O2 bung further down stream fix it.
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Interesting. These trucks have the O2s placed just how Holley advised. But, I'll give that a try.
 
Seriously though. We are driving old ass trucks. Every issue I’ve had I’ve been able to trace back to something feeding bad fuel or signal to the Sniper itself.

I’ve had mostly great luck with install and forget. My 45 and 55 have zero issues. Crank. Drive. Nothing but perfect. Same with most I’ve installed.

What’s weird. My 60 has the full WOT bog in 4th gear only. I can let off the gas to 65% and it picks up acceleration but won’t do it in the other 3 gears. Put a new sniper on the Truck because I had one sitting here for a project. Same thing. This tells me it’s an input.

This current truck. Same deal. Came to me to fix the dying. I did not only swap the Sniper I swapped every sensor. Used a spacer on the O2. All new fuel system.

Same issue. Something is going on In this well running new rebuilt motor that’s telling the Sniper something it does not want to hear.

That’s in the data logs I’m sure. Just need someone smart to read em when I take em.
 
Zjohnsonua said:
Interesting. These trucks have the O2s placed just how Holley advised. But, I'll give that a try.
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The new manuals have a diagram that says 8” past collector and 45* to the up side

The OG sniper directions said none of that and most all I did are right where the header ends at 90* up.
 
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