Wow what a hassle. 🙄I have a 427 w with a Edelbrock 750 that has run flawless for 7 years. I was thinking about a Sniper. But not now. After seeing all these YT videos of Sniper problems, I am keeping my Edelbrock 750. 😊
Holley powdercoated the inside of the sniper units. Eventually the gas eats the coating and causes problems. Pull off the plate on the passenger side where the return line goes. Pull out the diaphragm and you will see where the coating is missing and the screen will be clogged.
I had a similar issue with the Holley Sniper EFI install on my 1982 GMC 2500C stock 350. After some fretting and removal of the throttle body, I discovered the kit supplied manifold gasket did not fit properly. The gasket allowed a vacuum leak between the manifold and front of the throttle body. I swapped the new gasket for the original and it total fixed the problem. Best wishes!
I solved similar issues through debugging. The key thing that helped me was disconnecting all throttle rods/cables and *then* setting IAC. By doing this I discovered that my throttle linkage was just not exactly correct - mine would run great when cold but then the idle would not settle after running a few minutes. I rejiggered my throttle linkage so that I was certain it was having no impact at idle and that sorted the issue. Two other things I had to chase: (1) Vacuum leaks - my newly installed intake was too narrow for my stick spacer (Ford 289), (2) Must disable timing control (if you have it) when setting IAC (Holley has a video about this - "Setting Sniper Idle.")
I have a Holley Sniper 2300 on a Falcon 6 and a Powerjection III with spark control on my Clevo and the Holley has been nothing but a pain in the ass by comparison
Select your idle speed on the tuner. Disable idle spark control. Start the engine adjust idle to match the selected value. Turn key off for 5 sec set your iac hold for 5 percent.
Basically after the idle is set this truck will ramp the idle up to 1300rpm and the iac % says 0 even though the iac is open to 75%-100%. I installed another sniper on a different truck and it operates with no flaws, actually just passed emmissions with the other one. When your engine is around operating temperature you want the iac to read near 10%. Always cycle the key between adjustments, that's when this system learns minimum throttle position. Let me know how it goes!
U have some nice bikes in the garage. The sniper is frustrating. Im on my 3rd day of having it and the random stalling is getting old as well as the random loss of power at wot. I thought it was plug and play and self learning. Did holley fix problem
i just installed this on a 67 firebird 326. the IAC is all over the place with poor idle up and down. random engine shut down, and very poor restart as if it is flooded. i am getting ready too call holley today. is yours working properly now?
I don’t know if anyone said it but the screw is go the IAC not an idle adjustment like a carb. At temp set the screw in to get a 0 IAC percent and back out in 1/4 turns to get a 5-8 then restart should work fine. Also best to use a return spring on the throttle.
Make sure your spark plug wires are away from the iac. Mine was doing this and I moved all the plug wires away from the back, "difficult with a chevy" and the problem went away. Brand new wires too but still affected the iac. Hope this helps.
I have had similar issues where idle would stick high found wire by iac and moved it around the back instead. However issue has progressed and now shuts ecu off hand held shows no data.
Had the same issue from the first day it was installed, along with some other issues that might have been set-up/adjustment related. Then one day it just stopped on me in my driveway (thank goodness) and wouldn't start back up. I got Holley tech on the phone, went through a few steps and it was determined that I have a defective ECU. Less than 150 miles and it & it took a dump. This is after 2 other "Out the box" parts were DOA and had to be swapped out just to get the car running. I'm not necessarily bad-mouthing Holley or their products but either their quality control needs to step up or I'm just one UNLUCKY SOB. Or both. By the way how long has it been since they swapped out your ECU? Have you had any other issues? Thanx, BONE
It's a customer's and he doesn't put a lot of miles on it. We have had another unit on a friend's suburban for years now that has worked great with no problems. He doesn't have many miles on it either but it passed emissons and hasn't had this issue in any way.
Ok, I'll look into that, I just got the unit back from holley a few days ago and the customer don't have many miles on it yet. They replaced the ecu and the lcd display. Not positive it's fixed yet. Thank you for the input,
just so you know if you set the desired idle to 700 and then manually adjust it above there the iac will be closed trying to get the desired idle trn the manual idle below 700 and the iac will take care of the rest
So the real problem was that randomly the iac % would drop to 0% on the display and the actually iac air passage was at %100. I was turning the idle up and down to influence the iac position
I just got my Sniper installed a month ago. I am now seeing the exact same thing. It will start fine, idle down just fine, but after a short time of driving, the idle jumps to ~1500, and will NOT come down until I turn the motor off, then restart, then everything is fine again. This seems to happen after the engine is fully warmed up. When this is happening, the TPS is 0%, and IAC is 0%, but just like you, I can put my finger over the rectangular hole and can feel the suction. I have started a support call with Holley but have not heard anything back yet
Ask for Josh Johnson at holley tech support. They replaced the ecu for this unit and so far it had been fine. Email him the link to this video. He'll remember
Did you find a fix? I believe if your run a dual plane w split left and right side plenum, u need to run a spacer or mill down the desperation in the plenum so the iac can get a proper reading
I don't have that system I have an original edelbrock pro flow. What I'd suggest is you familiarise yourself with how the system works there's a reason the IAC is not being commanded properly your looking past the actual issue.
Why would we bring everything we hate about modern cars into our old cars. There's nothing better than a Well tuned holley. Even a Dyno tester will prove that
Fish, the O2 sensors are junk that they send out in this package, so buy a VW one since they're rated for a hundred thousand miles, second, replace that IAC that I believe is a Chrysler one with a better aftermarket IAC. Look up Holley Sniper issues on UA-cam and you'll find a video that explains what I've just stated. Good luck gentlemen. Hope this helps.
@1broncos7, do you know which make model and year VW 02 sensor to get and also the IAC , I have the sniper unit on order and rather just get it before I install
With the engine at 160 degrees, plug the iac port with tape, disconnect your timing advance line, get a vacuum gauge and physically adjust your timing until you get the highest vacuum reading. Now start aiming for your for fast idle with the goal of being 5 percent below the rpm setting you actually want. All the while adjusting your distributor and the idle mixture screw to maintain that maximum vacuum reading. Once you are in the ball park shut it down, unplug your iac and attach your timing adv line again. Start it up and see where your iac reads. Fine tune the idle mixture screw to get between 2 and 10 percent.
So...even though my timing was spot on before I installed the EFI...I should readjust it again? My IAC stays at zero whether it is plugged or not until you press the accelerator....Then it goes straight to 20 and stays there with no variation. It reads zero-no gas pedal or 20-gas pedal.
The car idled great when it was carborated but I just switched over to the sniper and now I can't get it to idle although it starts great. Do you think my injectors could not be working after the initial fuel prime
this guy had a similiar issue and used a piece to tape to cover the IAC valve. Then adjusted it manually. Took the tape off and let the valve, take over. that seemed, to fix his issue. starts 0.23 second point. ua-cam.com/video/2tqJ_TCHXec/v-deo.html
I got so frustrated with mine I removed it and went back to carb ! I seriously want to beat it to death with a baseball bat. Running a 600 Quadrajet my cars runs perfect.... go figure.
So after reading comments. I'm super sketched about getting a sniper. What a nightmare, it appears to be!!!! I would rather just buy and stay with a stock set up, I'm thinking. So is this sniper system a piece of shit junk or what!?!
Treyton, the way to adjust the iac down is like this. With car off, place a piece of tape over the iac hole. Start the car and then adjust the idle screw out. Start with dropping the rpm 150-200 rpm (ie, if idle on handheld is set to 1000 rpm drop to 850 rpm) and then shut the car off completely, remove the tape and cycle the key to on so the ecu can save the changes. Start the car and check the iac settings in gear. If it is still not low enough, repeat until it is below 10%.
Not yet. Still working through it. Do you have a similar problem? Already warranted the throttle body assembley, lcd unit, and the 02s and it's still having this problem intermittently. I will keep the results posted. Getting back with holley this week
Wow what a hassle. 🙄I have a 427 w with a Edelbrock 750 that has run flawless for 7 years. I was thinking about a Sniper. But not now.
After seeing all these YT videos of Sniper problems, I am keeping my Edelbrock 750. 😊
Holley powdercoated the inside of the sniper units. Eventually the gas eats the coating and causes problems. Pull off the plate on the passenger side where the return line goes. Pull out the diaphragm and you will see where the coating is missing and the screen will be clogged.
I had a similar issue with the Holley Sniper EFI install on my 1982 GMC 2500C stock 350. After some fretting and removal of the throttle body, I discovered the kit supplied manifold gasket did not fit properly. The gasket allowed a vacuum leak between the manifold and front of the throttle body. I swapped the new gasket for the original and it total fixed the problem. Best wishes!
I solved similar issues through debugging. The key thing that helped me was disconnecting all throttle rods/cables and *then* setting IAC. By doing this I discovered that my throttle linkage was just not exactly correct - mine would run great when cold but then the idle would not settle after running a few minutes. I rejiggered my throttle linkage so that I was certain it was having no impact at idle and that sorted the issue.
Two other things I had to chase: (1) Vacuum leaks - my newly installed intake was too narrow for my stick spacer (Ford 289), (2) Must disable timing control (if you have it) when setting IAC (Holley has a video about this - "Setting Sniper Idle.")
I'm having the Exact same Issue! This is my second unit. First one crapped out after 200 miles or so. ECU went bad on that one.
Just a heads up to anyone following this, holley replace the ecu and the problem is solved
How/where do you get a new ecu?
@@geoff13man I read he wrote HOLLEY
I disagree. I'm having a similar issue. Purchased sniper in June of 2021.
Thanks for the video. I just installed my sniper a month ago and got several different "fixes" from Holley tech and still have the same issue as you
I have a Holley Sniper 2300 on a Falcon 6 and a Powerjection III with spark control on my Clevo and the Holley has been nothing but a pain in the ass by comparison
Select your idle speed on the tuner. Disable idle spark control. Start the engine adjust idle to match the selected value. Turn key off for 5 sec set your iac hold for 5 percent.
THANKS FOR SOME REAL WOLRD ADVICE
Basically after the idle is set this truck will ramp the idle up to 1300rpm and the iac % says 0 even though the iac is open to 75%-100%. I installed another sniper on a different truck and it operates with no flaws, actually just passed emmissions with the other one. When your engine is around operating temperature you want the iac to read near 10%. Always cycle the key between adjustments, that's when this system learns minimum throttle position. Let me know how it goes!
badchickenracing1
Mine the tps was not plugged in all the way, doing what yours is! With iac unplugged it was reading all over the place!
J Minnick I'll have to look into that. Pretty sure my tps is always reading
U have some nice bikes in the garage. The sniper is frustrating. Im on my 3rd day of having it and the random stalling is getting old as well as the random loss of power at wot. I thought it was plug and play and self learning. Did holley fix problem
Well my stalling was related to iac startup setting set at 85 all the way across and fires up nice. Very nice setup
i just installed this on a 67 firebird 326. the IAC is all over the place with poor idle up and down. random engine shut down, and very poor restart as if it is flooded. i am getting ready too call holley today. is yours working properly now?
I don’t know if anyone said it but the screw is go the IAC not an idle adjustment like a carb. At temp set the screw in to get a 0 IAC percent and back out in 1/4 turns to get a 5-8 then restart should work fine. Also best to use a return spring on the throttle.
Make sure your spark plug wires are away from the iac. Mine was doing this and I moved all the plug wires away from the back, "difficult with a chevy" and the problem went away. Brand new wires too but still affected the iac. Hope this helps.
Never heard anything like this before.
Always something new to learn.
I have had similar issues where idle would stick high found wire by iac and moved it around the back instead. However issue has progressed and now shuts ecu off hand held shows no data.
Had the same issue from the first day it was installed, along with some other issues that might have been set-up/adjustment related. Then one day it just stopped on me in my driveway (thank goodness) and wouldn't start back up. I got Holley tech on the phone, went through a few steps and it was determined that I have a defective ECU. Less than 150 miles and it & it took a dump. This is after 2 other "Out the box" parts were DOA and had to be swapped out just to get the car running. I'm not necessarily bad-mouthing Holley or their products but either their quality control needs to step up or I'm just one UNLUCKY SOB. Or both. By the way how long has it been since they swapped out your ECU? Have you had any other issues?
Thanx,
BONE
It's a customer's and he doesn't put a lot of miles on it. We have had another unit on a friend's suburban for years now that has worked great with no problems. He doesn't have many miles on it either but it passed emissons and hasn't had this issue in any way.
Ok, I'll look into that, I just got the unit back from holley a few days ago and the customer don't have many miles on it yet. They replaced the ecu and the lcd display. Not positive it's fixed yet. Thank you for the input,
just so you know if you set the desired idle to 700 and then manually adjust it above there the iac will be closed trying to get the desired idle trn the manual idle below 700 and the iac will take care of the rest
So the real problem was that randomly the iac % would drop to 0% on the display and the actually iac air passage was at %100. I was turning the idle up and down to influence the iac position
@@badchickenracing1 yup i have exact same issue holley is blaming rfi will be re arranging wires today. Scared to drive it since i had to tow it home
I believe you have to turn the manual idle up, it shouldn't stall when you cover the IAC hole.
Wiring looks pretty messy… follow instructions (exactly). EMI can damage things quite easily! Just a thought!
I just got my Sniper installed a month ago. I am now seeing the exact same thing. It will start fine, idle down just fine, but after a short time of driving, the idle jumps to ~1500, and will NOT come down until I turn the motor off, then restart, then everything is fine again. This seems to happen after the engine is fully warmed up. When this is happening, the TPS is 0%, and IAC is 0%, but just like you, I can put my finger over the rectangular hole and can feel the suction. I have started a support call with Holley but have not heard anything back yet
Ask for Josh Johnson at holley tech support. They replaced the ecu for this unit and so far it had been fine. Email him the link to this video. He'll remember
Also try unplugging the alternator while it's acting up. We replaced the one on this truck right after I got the sniper unit back from holley
Same problem holley says it rfi will look everywhere today.
Good information. Thanks for posting this!
Did you find a fix? I believe if your run a dual plane w split left and right side plenum, u need to run a spacer or mill down the desperation in the plenum so the iac can get a proper reading
Its cause your using the round door key not the square one
Are you still running the sniper efi? Thinking of installing efi in my k5.
I don't have that system I have an original edelbrock pro flow. What I'd suggest is you familiarise yourself with how the system works there's a reason the IAC is not being commanded properly your looking past the actual issue.
Retrogamer1010 holley replaced the ecu. That fixed it
Why would we bring everything we hate about modern cars into our old cars. There's nothing better than a Well tuned holley. Even a Dyno tester will prove that
I AGREE 100% !!!!! TOO MUCH TIME SPEN FUKING AROUND WITH THESE SNIPERS !!!! WAY WAY WAY TOO MUCH TIME !!!!!
Fish, the O2 sensors are junk that they send out in this package, so buy a VW one since they're rated for a hundred thousand miles, second, replace that IAC that I believe is a Chrysler one with a better aftermarket IAC. Look up Holley Sniper issues on UA-cam and you'll find a video that explains what I've just stated. Good luck gentlemen. Hope this helps.
which part number was ur vw o2 sensor? Ive already replaced once and it was special order and expensive af
@1broncos7, do you know which make model and year VW 02 sensor to get and also the IAC , I have the sniper unit on order and rather just get it before I install
With the engine at 160 degrees, plug the iac port with tape, disconnect your timing advance line, get a vacuum gauge and physically adjust your timing until you get the highest vacuum reading. Now start aiming for your for fast idle with the goal of being 5 percent below the rpm setting you actually want. All the while adjusting your distributor and the idle mixture screw to maintain that maximum vacuum reading. Once you are in the ball park shut it down, unplug your iac and attach your timing adv line again. Start it up and see where your iac reads. Fine tune the idle mixture screw to get between 2 and 10 percent.
So...even though my timing was spot on before I installed the EFI...I should readjust it again? My IAC stays at zero whether it is plugged or not until you press the accelerator....Then it goes straight to 20 and stays there with no variation. It reads zero-no gas pedal or 20-gas pedal.
Probably be hard pressed to find an idle mixture screw on this setup.
IAC is picking up high intensity stray signal from your distributor
did the ecm swap stop the hand held monitor flicker when you turn the key on?
I wish I could post pictures my IAC says 75% and doesn't change when it idles it just says 75% in a red square
Is it a vacuum leak?
The car idled great when it was carborated but I just switched over to the sniper and now I can't get it to idle although it starts great. Do you think my injectors could not be working after the initial fuel prime
treyton wood do you have a base gfc loaded in it*
treyton wood after it starts can you rev it?
What is a base gfc? And I can get like one rev then it dies
Could be too much fuel or vac leak or even exhaust leak. Mine runs much better than carb.
this guy had a similiar issue and used a piece to tape to cover the IAC valve. Then adjusted it manually. Took the tape off and let the valve, take over. that seemed, to fix his issue. starts 0.23 second point.
ua-cam.com/video/2tqJ_TCHXec/v-deo.html
I got so frustrated with mine I removed it and went back to carb ! I seriously want to beat it to death with a baseball bat. Running a 600 Quadrajet my cars runs perfect.... go figure.
So after reading comments. I'm super sketched about getting a sniper. What a nightmare, it appears to be!!!! I would rather just buy and stay with a stock set up, I'm thinking.
So is this sniper system a piece of shit junk or what!?!
Dude i got one a year ago im still having annoying little issues like this with it, it pisses me off
no one mentions, ZERO MPG benefits only HP.. and I've never liked how my sniper runs, def not a fan
Any cure found for this?
I sent the unit to holley and they replaced the ecu. Email their tech support
Thank YOu
Save your money leave your carb.on
I cant believe all the problems with this cheap Holley system. Should've saved up for a better system.
Have the exact same issue with mine, any conclusion to this issue? It's very annoying.
Patrick Haire holley replaced the ecu. Email there tech support and ask for Josh johnson.
badchickenracing1 that fixed the issue for good?
Patrick Haire yeah it wouldn't go more than a day before it would act up, now it has been fine for weeks
Mine is doing same thing! I got it a week ago!
rednkchris let me know what they say if/when u call Holley.. i havent had time to mess with mine yet.
my car idles for about 3 seconds then stalls i have messed with the idle screw and tried it all over any ideas? and my IAC is at 75%
treyton wood if your iac is at 75 you need to turn the idle set screw in about a full turn and try again.
What intake manifold and engine?
I have a built 351w with a edlebrock rpm intake I believe and I have moved the idle screw all the way from the bottom to the top.
treyton wood make a video and post it. So does the engine run well under load? Cruise? Has it ever idled well?
Treyton, the way to adjust the iac down is like this. With car off, place a piece of tape over the iac hole. Start the car and then adjust the idle screw out. Start with dropping the rpm 150-200 rpm (ie, if idle on handheld is set to 1000 rpm drop to 850 rpm) and then shut the car off completely, remove the tape and cycle the key to on so the ecu can save the changes. Start the car and check the iac settings in gear. If it is still not low enough, repeat until it is below 10%.
Did you get this Figured out?
Not yet. Still working through it. Do you have a similar problem? Already warranted the throttle body assembley, lcd unit, and the 02s and it's still having this problem intermittently. I will keep the results posted. Getting back with holley this week
Just got mine on last night haven't got to set Idle yet.
Read my other comment. I posted in the wrong spot
Probably because your idle was set to 900+ rpm