Holley sniper lean stumble. I'm new to Sniper.
Holley sniper lean stumble. Oct 3, 2018 · Here's a screenshot of a lean stumble from a datalog I created tonight. The other night on my drive home on the highway the engine began to stumble in the 1200-1800rpm range, no power, and the AFR went very lean. 9L. Not sure where to start to get a bigger Fuel was being delivered to the EFI but the fuel map suggested it wasn't getting enough fuel. I'm not an EFI master, but I've been learning about the Holley products (sniper specifically) for the last 2-3 years on my vette. I found that many people had similar issues and the pressure regulator in the Holley Sniper isn't great and can fail. Jul 12, 2023 · I can clearly see the leaning out of the a/f ratio when the stumble is happening. As mentioned by Danny, if the AE vs TPS Blanking is too low it will invoke Open Loop. The May 18, 2025 · Chasing a lean AFR spike and off-idle stumble/stalling on a BBC with Super Sniper and manual transmission. Not running timing control, and timing is set to 12°/33°. Exhaust checked, two header bolts were loose, but tightening them didn't Nov 7, 2023 · Hey everyone, I’m currently dealing with a lean tip-in issue. Whether you’re experiencing rough idling, stalling, or poor performance, this blog will provide practical solutions. You can see the RPM drop well below idle (due to the stumble), and the AFR jumps like crazy before being corrected. Ignition is all new MSD Pro Billet distributor, MSD Digital 6 CDI box, Blaster 2 coil, and new plug wires. 5-14. This is a new Holley 4150 Carburetor on a new SBC 400 crate engine. That said, I'd switch the accelerator pump discharge nozzle to a 35 after adjusting the pump lever. Jun 22, 2023 · My recent woes, that sounds the same at yours, was lean out due to apparent crud in the secondary metering. I have a couple datalogs created and will get those attached here. I had a very bad lean stumble when I hit the accelerator (at idle or under load). I did a bunch of research on the Holley forums. - Holley Performance Products Forums Home Forum Holley EFI Sniper EFI Jul 5, 2012 · Cure The Bog And Sluggish Response On Your Holley Four-Barrel Carburetor, By Properly Adjusting The Accelerator Pump Assembly. TPS shows noise and won’t always return to 0%, and I’m debating whether to tune it out, or revisit hardware like the progressive linkage. This is manual transmission, mild 350 SBC. But Sep 18, 2024 · Here's my issue: Between 2000 and 3700 RPM, under load, if I go to full throttle (WOT) my engine bogs/stumbles/misfires badly. He takes out the 65 primary jets and puts in 73 jets and left the secondary size at 68. Jun 29, 2025 · Hello. So I have a customers car that's a '66 Chevelle with a Chevrolet Performance Crate ZZ454/440 and a TKO600 5 speed. I also assume the majority of the rest of the lean spots in the datalog are also too lean in the Base Fuel Table. 031 out of box and the . After this starts, it also develops a problem idling, by surging and slowing until it stalls. The datalogs show a very LEAN condition after shifting, and when first starting out from a stop. I installed a couple months. If I back off the throttle to ~50%, it doesn't stumble or misfire. Even though it idles at around 13. May 13, 2014 · Cure the bog and sluggish response on your Holley four-barrel carburetor by properly adjusting the accelerator pump assembly. The stumble is smaller when I mash it because it's revving through there faster, and (I assume) road speed and carb air are faster, but it's still there. In this video, we explain the most common fixes for a off idle stumble on your Holley Carburetor. Understanding these tips can help you diagnose and fix common problems. I had to upgrade to a 340lph pump and the problem went away. It's a Ford 300 4. Apr 18, 2020 · Hi Everyone. Once above ~3700 it runs great all the way up to redline. '92 Ford Mustang GT: 385"/6. Have an annoying off idle stumble you cant seem to get rid of? Here are some tips on what to look for and how to work through the problem. 041 was just way to much but the guy said the off idle stumble was to lean and need it to be richer. Nov 1, 2018 · Did you buy the complete Sniper system with the fuel pump? I have the Terminator system and I know from experience they are sensitive to fuel pressure. 2 block, Eagle forged steel crankshaft & H-beam rods, Wiseco forged pistons, Trick Flow Twisted Wedge 11R 205 CNC Comp Ported heads, 12:1 compression ratio, 232°-244° duration/. 5 a/f, it seems crazy rich just from the smell and the eyes burning. Learn Table is down to just dialing it in. Ive connected the laptop and tried the ae vs tps. Sep 5, 2022 · Used the million posts of great advice and info on this forum to get my Sniper as far as it is, chasing away the gremlins. Jan 6, 2023 · There is a wealth of knowledge both on this forum, and the web (including EFIsystemspro) on the sniper. I find the most helpful datalog function, is overlaying the datalog on your Config File. I cant get in and out of my garage without stalling it up to about 1800rpm and traffic is a nightmare. Dive in to keep your Feb 22, 2014 · I have an 87 FJ60, 260,000 miles, de-smogged, DUI HEI & Holley Sniper that I would call my daily driver. So that's the setup and it runs great when it's warmed up. I'm new to Sniper. I'm not sure where to get the Config File from! If it helps, I chose the Street/Strip config. First time posting here, but I've definitely used this forum as my primary troubleshooting source. Closed Loop is working, but driveability off idle is rough, especially from a stop. I had a 200lph pump that could not keep up with the demand and every time I laid in to the throttle i would get a stumble and a lean spike on the AFR gauge. There have been ECU firmware updates since then, and consequently the Sniper EFI AE vs TPS RoC Blanking threshold value has been decreased to "7" (before Closed Loop idle problems occur). I took it out today for the first time in about 4 days and I noticed the car had an intermittent stumble where it would seem to cut out about every 30 seconds or so and this would Sniper EFI Tuning & TechMay God's grace bless you in the Lord Jesus Christ. So far I checked spark plugs and they look OK. If your car or truck is equipped with a Holley four barrel carburetor and stumbles upon acceleration, more than likely the carburetor needs an adjustment to the accelerator pump assembly. 3L SBF, Dart SHP 8. I have a stumble when starting from stop sign. We aim to make troubleshooting straightforward and stress-free. I figured I'd post a datalog and my current GCF tune on here to see if anyone can take a look when they get a chance and give me some pointers on how to correct this issue. Running the basic Sniper EFI system. Your datalog shows that the engine is getting a pretty big shot of fuel when you hit the throttle and then recovers on the rich side. Sniper 2 manual trans driveability issues, ocassional clutch-in stalls, erratic IAC. Oct 19, 2022 · When they don't make contact you'll lose fuel from that injector and the system will go lean while the Sniper attempts to compensate for the loss in fuel. Jul 10, 2017 · That is stock out of the box specs from holley but the shooter size is . You said it was running Feb 28, 2025 · Wanted to share a solved problem on a 1968 Camaro. If I take a ten mile Oct 21, 2022 · Remember that a rich stumble will appear as a lean spike at the WBO2 sensor. 623" lift/114° LSA H/R camshaft, TFS R-Series FTI Comp Ported intake, BBK 80mm throttle Off idle lean stumble, sputters when holding steady off idle pedal. It was running fine with the stock distributor, but I wanted to utilize the potential of my Sniper by Apr 20, 2020 · The major lean spots when you slip the clutch to get it moving without moving the TPS, the RPM drops into the spots on the map that are way too lean. Aug 19, 2024 · This problem started about a week ago, the engine goes lean and stutters when accelerating at low RPM. In this guide, we’ll explore troubleshooting tips for Holley Sniper EFI. Have an issue where if I try to hold the throttle just off idle (not stabbing the throttle just slowly holding) the A/F ratio goes lean, I get some backfiring and won't hold a constant RPM. Open it up a little more and it will hold steady at 2000 RPM. In the last year I have been struggling to fix a consistent hesitation I get under acceleration after it warms up. Jun 19, 2019 · Using the Holley Sniper EFI software (LINK), look at where the live cursor moves to during this occurrence, and manually tune that area of the Base Fuel Table (enrich or lean) & Base Timing Table (optimize ignition timing). Aug 8, 2022 · PY Online Forums - Bringing the Pontiac Hobby Together > General Classic PONTIAC TECH > EFI Tech > WOT from a dig og just off idle stumble May 11, 2025 · But, like any system, issues can arise. I have a Super Sniper 550-519, and I'm having some issues with it since installing timing control. I’ve been running the Sniper for several years now and it’s been pretty flawless. So driving more normally and rolling on the throttle it's not present. Plug wires seem OK and timing light flickers on all of them. May 1, 2020 · Ive been running a Holley Sniper for a about four years now. Jun 28, 2022 · Sniper EFI Tuning & TechOriginally Posted by Danny Cabral Formerly, "15" was the suggested value for both AE vs TPS & MAP RoC Blanking, per Holley Tech and the Sniper EFI instruction manual. Dec 19, 2022 · C3 Tech/Performance - Holley Sniper stumbles - I have a Holley Sniper system on my 1968 with a 383 Stroker and it has been running good. Review this recent thread and when it's running rough pull the air cleaner and see if you're getting fuel from each injector. One guy had an issue with his regular that made it fail intermittently. It’s happening with very slight throttle input coming off idle from a stop or slow roll. Nov 24, 2024 · There's also a small stumble when mashing the loud button through that range. Everyone here will generally help if they can. I tried several things including replacing the original Primary 31 Nozzle with a 35 nozzle Feb 11, 2019 · So having a problem with my sniper, its almost to the point im about to pull it off and go back to carb because its totally horrible to drive. gxvfhz4 wujq0r mwuew sx1po gy5dxqm zlbd u9mw j7x 2vza5cl9 th