Intermittent stalling usually points to radio frequency or electro-magnetic intereference (RFI/EMI). First thing I would check The Sniper EFI system looks at the closed-loop fuel compensation required to reach your target AFR. This is actually more troubling than the sound you originally described. Throttle Tip-In tuning can be a bit of a challenge but I'm confident you can get this resolved, Mike.Let me start by saying that unless you've really done a lot of driving on the system in some useful learning situations then I would set this issue aside and not even think about it. If I adjust idle screw out to get the tps to zero or even 1% the engine will not idle. I think that the more important point is that Holley kept sending him units until everything was working. With the engine still idling high park, set the brake, open the hood, and remove the air cleaner. I've changed all the Please give this a try and let us know how it works! You can adjust this number up or down but there is really no need to change it unless the car is stalling.The sucking sound is just what happens when the Sniper EFI System is paired with certain intake manifolds. The throttle position should be zero. I'm wonder if the iac can cause this. Thanks for the info Chris. The resulting resistance can burn up fuel pumps, wiring and relays. Turning off and then on again, the engine returns to normal. Even though the Sniper's fuel map is programmed to provide the correct amount of fuel via injectors spraying at 60 PSI, if the pressure is jacked up to 90 PSI the wideband sees that you are rich and faster than you can even detect it audibly lowers the duty cycle to inject the correct amount of fuel. Next, reach down into the secondaries and push the butterflies closed. When you experience this, before you touch anything or shut the engine down, first look at your TPS and your IAC. But before you adjust the ECU to lean the idle out, first confirm that your fuel pressure is right. The IAC should display a 2-8% to bring the idle up to the actual target. I'm thinking it could be the fuel pressure--- since I have a new Spectra EFI tank and there's been some reports of the interior coating coming off and gumming up the pump however the sniper display DOES NOT show fuel pressure.the Sniper DOES measure fuel pressure on its own - i've confirmed that with holley techs as they told me to purchase the fuel pressure gauge that can just hook up to the 1 wire gauge harness from the Sniper. Idle > IAC Kick. Simply turn the idle speed screw on the linkage in until the throttle plates open enough for the idle to increase. You want to ensure that nothing is hung up in there.The only thing that I can think of that would cause the fuel pressure to spike when the motor starts is the increased fuel flow at the higher alternator voltage (jumping from 12.0 to 13.5 volts or so.) You should get a light spray evenly distributed in all four barrels. datsun sniper efi Holley RetroBright This 1974 Datsun 620 Bulletside Cruises With The Help Of Sniper EFI Bradley Iger 01/13/2023 features Latest News sweepstakes 2023 Hemi Engine Sweepstakes Gen III Hemi Enter To Win Holley's 2023 Hemi Engine Sweepstakes For Your Chance To Win A 600+ Horsepower 392 Stroker! Get On The List for Emails Straight From Our Pro? This software is going to allow you to open both the configuration file and the datalogs that you create, overlay them and you can get a much better idea of what is happening. Drive great and idles perfect at stop signs. While you have over 200 miles on the system, you must realize that in the part of the map where the ECU finds itself during lanches you might only have a total of 5-10 seconds in any given cell. Holley will take a look and tell you you have RFI and wish you good luck in finding it. check out the. Without it you are working in the dark. when things aren't working and this provides just that. From herethe cycle continues and I am Thanks for any info./insight you can provide, Mark. Commanding the engine to automatically increase speed when switching into drive is a little scary to me though. If you complete the process and find that the IAC is less than 2% at idle, repeat the process and use the set screw to make the RPM about 60 RPM below the target. Should i adjust idle screw with the fans already on? Please help. If you drop it too far the engine will stumble or stall when coming off the throttle with the car out of gear, so you'll know when you've gone too far. You can drop it down and you will find it will behave more like you expect. Target AFR, A / F = 13.5 )Take a look at your AFR during the starting process. Some suggestions: i did have the same problem.try lengthening the lever of the throttle.meaning the length from the center of the throttle to the point where you attach your cable or your rod from the peddle. It starts cold fine, its just when its hot. First, check to make sure that the IAC is properly mounted and connected. It runs perfectly fine other wise. If your TPS has snuck up to 2% then your IAC will be at the hold position, which by default is 30%. The IAC going to 30 is normal. I'm new to the efi thing and any help would be seriously appreciated. Suddenly, the engine accelerates alone, hears a great deal of air being sucked in, To be honest, you sound like an ideal candidate for Sniper ECU ignition timing control. If it does then you can put on a heavier spring so the advance doesn't come in as fast, or use a lighter weight. May God's grace bless you in the Lord Jesus Christ. If it is not a problem with the Sniper EFI System itself then it could be an issue with some sort of harmonic involving the fuel pump. I have been reading these posts and have learned a lot. It's called tuning. Okay, try my method. Sniper is still learning so it will continue to improve.Second, you may have heard the phrase, "correlation is not causation." Worst case you'll have a spare on hand, and if the TPS is faulty you will have solved the mystery. Let me start with the engine not starting until you press the throttle. I installed another return spring for the rear plates problem solved instantly. That's a nice change of pace--a low idle issue! Bolt-on carburetor style EFI for your classic car or truck. To get it to idle the tps is at 2-3-4% even with linkage disconnected and a return spring installed. The data that you provide shows that you have at least two problems. This question is really outside both the scope of what we try to discuss in the comments section as well as the overall subject of this article. It's not necessary to drive it that way. Do you have any clue? carburetor setup, but it does blow when I can't jump on the highway like I use If your TPS is at zero and your IAC is at some random number above 8% (but not exactly 30%) then for some reason your engine has not met the conditions to ramp down to target idle. When I put it in gear, it drops so low that it will stall if I don't add throttle. Fortunately, I have an article that goes into this in some detail. Ensure all your sensors are displaying proper values. If you've been running a filter then you have to wonder if you have a legitimate Walbro pump.If you install a new pump and the noise is still coming from the Sniper EFI System then only the dealer who sold you your system can help you. After a stall the car will restart but will be in a high idle. But I think it is safe to say that you are now at a point were some manual tuning is a good idea. The engine makes very low vacuum at idle. ?I never had my Carb Cold start RPM any higher then 1600 RPM.THANK YOU. I am extremely suspect of what you were told about the Sniper ECU monitoring fuel pressure, for several reasons. When you first posted this I had no idea how to respond. This item: Holley - 543-105 EFI Idle Air Control Motor , Black $71.72 Holley Sniper EFI 870001 Throttle Position Sensor $34.60 Holley 860004-1 92MM Sniper Throttle BDY $223.93 Customers who viewed this item also viewed Page 1 of 1 Start over Holley EFI Idle Air Control (Iac) Valve Motor 30 13 offers from $79.56 Resistance results in heat and heat results in more resistance. Turn the idle speed screw on the primaries in about 2-3 turns after it makes contact with the linkage and starts opening the primary throttle blades. If you hit the gas it pops & backfires through the throttle body. In fact, it is those users who seem to end up most impressed with the system. If you go too high then the motor will not return to your target idle when you come off the throttle. I can get it to fire up on the I never had a problem with this. No big deal, just time to re-adjust! It really takes a lot of throttle tip-ins before you get anywhere near "learned" in this part of the fuel map.Based on your description, it sounds like you have a lean stumble. I was looking at a data log from my truck earlier this week and noted that at idle my IAC was zero. As always, I recommend great restraint in changing any of the parameters until a significant amount of learning has taken place. After 50 on the throttle position I'm not sure if the whistle goes away or you just can't here it anymore. any advise would be appreciated. It drops about 200rpm when clutch engages. 90% of problems, (INCLUDING MYSELF) could be answered/fixed by just reading the instructions. That, I am afraid, is going to involve a little bit of luck if you don't want to create a 250 MB data log. The Sniper EFI replacement throttle body for Autolite 1100 carburetors will be right at home on most early in-line 6 cylinder powered grocery getters or weekend cruisers. Price Point: $, Advanced throttle body injection systems capable of transmission control and more. I've abbreviated it just a little bit but am appreciative of the added insight your comments provided.Off-idle performance can really be a challenge to self-learn but be assured that it can almost always be done. Since that has long been corrected we have moved that information to the bottom of the article.). But I still get the iac at 0 and the rpm at 1200. Very annoying ended up being simple my rear plates would stay open constantly it was driving me nuts I'd let off the pedal idle at 1300 blip the throttle a few times finally come back to 850. Using the handheld, navigate to Tuning > Basic > Basic Idle and ensure your target idle speed is set to the RPM you desire. Will restart but only for a minute or so a couple of times then shuts down fuel delivery and will not restart. But nothing beats a good solid gut-check This only happens when coming to a stop and the idle is ramping down to the set idle RPM. Contact whomever sold you your system or Holley directly. This car has never idled under 900 without stalling with 3 carbs and does the same thing with sniper edit. Turning it off and back on would reset it, and then it would work as advertised for a while. Thank you. Thanks again. Could be a bad IAC motor, replace it and see if that solves the problem. If this is the case then I would look particularly close at the IAC hold position and IAC ramp start.Let us know what you find and what works for you! You will find a startup IAC percentage, an amount of time it holds at that percentage, and an amount of time it takes to idle down to the normal idle speed.By default, that number is 50% at normal operating temperature. I have driven a stand-alone transmission controller for the 4L60E in my (then) Sniper-equipped '95 GMC pickup using the Sniper TPS with complete success. Reply Quote. After only running for about 15 minutes or so the system starts to fail stalling the motor. I am having an idle issue (other than that is absolutely perfect). It could be a couple of things. I think in some of the Wizards with the handheld it doesn't use 57.5 as the default. As I have it set right now, my idle at park is in the high 700s and my desired idle in gear is set at about 700 cold (80 degrees) and gradually lowers to 590 once engine temp reaches 160 degrees. At any rate, once the setting was moved up, the RPM jumped right to the target RPM and was solved. I installed Holley Sniper on three other Mavericks here in Brazil and the problem also exists.I did not make any changes to the parameters, only on Target AFR and the correction on the Idle Speed Curve chart. I hold my foot steady in place it does this in 5 second cycles and if i let go of One of the most common symptoms of a Holley Sniper EFI problem is an air/fuel mixture that's too rich or too lean. Note too that the larger the throttle stab, the more brief the time in that cell and the more gradual the change.Here's what I recommend: Get somewhere where you can repeatedly stop and go. If you find that adding 5-10 degrees of advance helps then it's time to do reconfirm TDC. RPM = 1200My slow gear I leave with 650 RPM, the IAC Position I leave between 5 and 6%, the It's a Chevy 350 bored .030" over it has a cam in it what I was told is the cam has the firing order swapped. Your suggestion to remove the PCV valve is just for diagnosis purposes, right? The fuel pressure regulator in the Sniper is fairly simple and not prone to failure, as far as I know. it seems to ramp to 60 psi on the initial prime, but as soon as the motor start the psi spikes.I guess a workaround would be an inline return/filter regulator? and when I close the IAC's hole with his finger, the engine is normal.The data on the touch screen I see are:AFR, A / F = 35.6 When you set the Static Timing to 15, what did you read with the timing light? your IAC is at zero. EFI System Pro had everything I needed for my EFI upgrade. Hey Chris Only show this user . port that goes right on the inlet of your Sniper and makes installation a breeze.If your fuel pressure is solid at about 60 PSI then you should start looking at When I turn the key on I can hear it prime, but I don't think im getting enough fuel. I also noted that after some time, I could change those values as I saw fit. I would continue checking the electrical connections along the fuel supply. 400 engine, C6 3 speed automatic, with standard canister coil for ignition, and If it is already adding fuel, it may be worth expanding this into the area where the tip-in is occuring (and where there is no learning occuring. !I called Holley today, and before I could even described the symptoms the It started right up and we did your idle control fix and all is good at idle. There are six different acceleration enrichment tables that you can tweak and that may be the way to go. It is easily solved by installing a four-hole gasket or four-hole spacer (depending on your hood clearance issues.) If you go too low then it may stumble or even stall when coming off of throttle. )Since this isn't a consistent issue with all Snipers that tells me that different IAC settings tend to make the whistle. There is no sense proceeding until your TPS is at zero at key-on. I, too, wish you'd bought your Sniper from us! Software: Idle > IAC Settings > Idle Spark, Handheld: Tuning > Advanced > Advanced Idle > Idle Spark, After completing this 10-step process, if the temperature displayed on the handheld is still above 160 degrees the engine should go right to it's target. It is good to at least know that the Sniper fuel pressure regulator can have high pressure failure issues (contrary to what I posted to Scott back on April 13th!) When I first told him to check for leaks he looked back there and said "all good". Hello, Chris, thanks for the help.I have not installed the software yet, and I'm having trouble with two cars. I would start by datalogging the situation and seeing exactly what your learn table looks like in the area immediately around the tip-in. As I would slow down for a stop sign or stop light, the car would run really rough and the idle did not want to come down. All times are GMT-6. I readjusted my IAC, now it's perfect. Sorry I didn't buy from you but I didn't know you had sold them. All in all, considering the system has been installed for less than 2 hours drive time we're BLOWN AWAY at how quickly it is "learning" this engine. At some point you come upon problems that evade the easy answers and this is a good example. holley efi. You advise would be greatly appreciated. For the first couple of drives it was running well, Sniper EFI was working exactly as advertised. Running new vintage air system so the is only a single power wire to compressor thats why I asked if I needed to run input wire to ac relay or if iac would pick it up fast enough(which its not). If you get into the practice of hearing all three of these sounds you will know if you have a problem even before you turn the key to crank. What could be the cause? Be aware that there is a spring behind there and a diaphragm that you don't want to tear. I followed the instructions and set the IAC to 2-9% when warm with idle at 850 RPM. After pumping the pedal a few times at different times it dropped to zero and started to work. I was 20 minutes into a drive yesterday when all of the sudden the RPM increased not commanded. You might have a bad IAC, but you can also have a bad vacuum pod on the transmission. the gas it catches itself and runs fine at slower speeds. What an amazing site you have here. Using a Snap-on variable timing light so this is why I say timing is perfect. Cycled the ignition off. There's nothing wrong with manual tuning, but at this point that is just compensating for an inadequate fuel map. It sounds to me like it is way retarded.In the event that the timing is right then take a look at your AFR--the actual AFR, not the target. If they are closed, check the primaries. Have you ever experienced a high idle once the engine reaches 200 degrees?Ive set my idle the way you said and it works great until the engine reaches 200 degrees. It is probably that your RPM above the maximum point at which ramp-down can occur. Save Share. When you open your IAC to 30% you are naturally going to have a high idle condition. Interesting situation you have. The Sniper EFI remote IAC (Idle Air Control) and plug is designed to gain installation clearance on some Sniper EFI 2x4 installations. sniper Installation If you're installing a Sniper EFI system and almost ready to crank it over for the first time, this is the video for you! Part# 538-13. Once you've done this, the next natural step is to transfer the learn table to the base map, then go in and smooth out the sharp edges, which are going to be at these transitional states. Holley Sniper high RPM - IAC problem? The symptoms I had was a low cold start idle and going lean coming to a stop. At this time, TPS is 0%, IAC is 50 to 60%. I would suggest you take a look at that if you haven't already. So you installed your Holley Sniper. Just thought I'd ask as there isn't a lot of info out there. (Grease can sometimes do the same thing as a more permanent gasket sealer without making the removal of the air cleaner such a pain.). (It should be at or near 60 PSI at idle. Holley Motor Life To do this, open up the Initial Startup gauge screen that was used in section 17.0. Sometimes it sounds like it wants to crank at the start but runs out of gas. Both answers you've received greatly oversimplify the truth in favor of the answerer. After much diagnosis, I ended up replacing the intake manifold gaskets. Short drives is fine then it'll such high fuel pressure. Sniper EFI Problems - Holley Performance Products Forums Bolt on 4150 Flange Carburetor Replacement. I keep doing that with the same result. The first thing I'd do is check your fuel pressure with a gauge like this. The team at Holley has designed the perfect solution for your problems. Take it a step at a time. Then it will ramp down to 1200 but will not return to idle. I would disregard any correlation between idle control between the Stock and Street/Strip setups. The car cruises fine, and if I was to keep idle at 2000rpm the issue wont happen, its only when the car tries to ramp down to idle position.Thank you for your help, any advice would be appreciated.Thank you,Eric, Whenever we see the AFR go to "Heating" that is an indication that the ECU has been reset. Capability Range: Advanced Or is there something else I should Holley EFI Electronic Fuel Pressure GaugeI think its a little ridiculous that I cant see fuel pressure on the display even though its measuring it but whatever. Across the board, all of our customers say how impressed they were that it started and ran right out of the box just by following the simple installation instructions. It is simply for the benefit of the user. It sounds a little different from mine, since it commands a 1300 or so increase intermittently. It sounds like you need a bit more of a fuel squirt on acceleration, Brett. Properly configured, the Sniper does a fantastic job of responding to the transition from Park to Drive. If the TPS is even just 2%, the IAC will go to the hold position (normally 30%) and will not change until the TPS goes back below 2%.If you create a datalog you will be better able to confirm if something is not working correctly. Holly offers a very nice Analog-Style Fuel Pressure Gauge that is another option. I have been able to get it pretty That is the IAC hold position. Add To Cart. But as you see from the recent revision I did above you seem to be having a fixable issue. However based on your reply I connected the Fuel Pressure gauge and I have an entirely separate article on Solving RF Intereference Issues. Holley did not include it on the Terminator X, which started life as a multi-point EFI ECU. Edit I just ordered a Holley return / regulator and cap for the sniper ouletOh, this is not an OEM Master Kit, but the fuel pump should be the same EFI Pro shipped this kit. Could the IAC be broken/malfunctioning? The problem I experience is that after driving for about 10-15 minutes, the car starts idle to high. It could be that you've left a vacuum port unplugged, it could be that the throttle plates are misaligned (unlikely), it could be that your IAC is not closing properly. Running a bbc with coil - my timing is perfect. It is working fine when you restart the car, controlling idle perfectly at 8 steps open so it is unlikely to fail when the car warms up--or correct itself instantly when you restart it..So, if you don't have any vacuum leak, and the throttle plates are fully closed, the only thing I can guess is something is causing your ignition timing to change. Hello Chris. Going lower with the blanking might pay dividends, but there is so little room below 7/8 that you will quickly be in a range where every tiny variation in the TPS or MAP is throwing extra fuel into the engine. Idle : IAC Rampdown : IAC hold positionChange this by maybe 2% in either direction. Holley Pro-Jection TBI Replacement Parts - JEGS No, the idle speed curve setting isn't something that you normally worry about--and especially not down at minus 40 degrees farenheit. idle at 1100 on the "stock" file it's better with street strip.The IAC counts will be at zero. Thanks! If it is then something is commanding the ECU to open the IAC. When I am coming to a stop, the rpms will hang at 1200-1500 rpms. We offer some tips to help with that. back upthe RPMs shoot up to anywhere between 1500 and 2000 and they will not get I am having an issue with the IAC on the Sniper. Even at 0% it's sucking a bunch of air through the IAC port. If you are using your Sniper EFI System to control timing, navigate to Tuning > Advanced > Advanced Idle > Idle Spark and ensure that the Idle Spark Enabled is set to Disabled. After the start process, If the idle speed is higher than the target idle then the IAC should begin closing as long as the TPS is below 2%. I figured out I was going the wrong direction when I was messing with the AFR programming. If you did not rotate the distributor to set the actual timing to 15 that might be the only issue. The Super Sniper will allow you to monifor fuel pressure if you add an electronic sender but this is not an option with the standard Sniper. Once you have done this the challenge is to create a datalog that includes the ":snap" you describe. Are these compatible enough? The Sniper will be controlling the timing so it will be based on a multitude of factors. And your question is very perceptive: You must first know whether the bog is a lean or a rich condition before you can make the correct adjustments. Took it for a lap around the block and came back. Put a strong piece of tape over the IAC breather hole--duct tape or something that couldn't possibly be sucked into the throttle body. (Plus they it just looks way cool in your engine compartment!) The biggest issue is these problems are intermittent meaning they do not occur all the time. If you look down and your TPS is 2% then either your throttle is stuck slightly open (which itself will cause the idle-up) or RFI riding on the TPS signal has caused the ECU to see the throttle as open and, as a result, open the IAC to the hold position. That changes almost instantly as the engine revs.Since the learning algorithm requires some time exposure to a certain condition to make larger changes, that half-second makes only the smallest impact. And yes, monitoring the fuel pressure is the right answer. other things that might cause the idle to faulter, but this is a good start. That is likely just confusing the issue.Instead, choose whichever setup most resembles your camshaft and stick with that. check, I guess after reading everyone saying how great the system is after In the Wizard, select the stock cam setting. Fuel Prime Multiplier is primarily a benefit to throttle-body based EFI systems. But I can tell you that for most people who try this it introduces so much RFI onto the Sniper that it never works right. Have a look--I think this is going to allow you to fix your idle problem. Price Point: $$, Robust, feature-rich multi-port EFI systems offer easy plug-and-play late-model V8 engine swaps.