Holley Sniper Help

[gkp200]

So I've had the car on the road for a little over 100 miles. I was hoping the sniper would have "learned" by now, but it is getting worse. It started as an off idle stumble, but once the RPM was over 1500-2000 it ran great. On a ride with my son today, it started breaking up at nearly any RPM or throttle position. The A/F ratio goes through the yellow into the red (14-30). I don't even know where to start troubleshooting. Any ideas?

The engine is a 351W/427 with TKO600, Holley sniper. The O2 sensor is in the passenger side pipe just after the 4 into 1.

I will call my engine builder on Tuesday, but any ideas you have to get started troubleshooting would be great. Thanks.

Gary

[Papa]

Can you provide a data log? The ONLY learning the Sniper does is build a learn fuel map. The rest needs intervention. If it was running good before, clear the learn map and start data logging where you are having issues. You may need to disable learning in some areas and leave it on in others.

[Papa]

Also, the Holley Sniper Forum is where you will find the most expertise.

[Norm B]

A little more information is required before offering anything but basic things to check. The issue might not be with the Sniper but, it could be responding to another problem. What ignition system are you using? Is your fuel pressure steady at 60 psi?

[gkp200]

Thanks for the input. I only have the small handheld screen with the SD card. I don't have a reader or software to display the data. The ignition is standard Ford coil and distributor not connected to the sniper. I have the Breeze fuel pump, fuel pressure regulator/filter with single fuel line to the sniper. I don't have a fuel pressure gauge, so I don't know the pressure.

[seagull81]

Why do you have a separate fuel regulator? My Sniper has it built in.

[Papa]

A couple of things:

1. The Sniper has a built-in regulator and you shouldn't be running a separate regulator.
2. The Sniper should have both feed and return lines, although I do believe I've seen where it can be configured with no return line.

The software is available as a free download from Holley and you can get a cheap USB card reader to allow you to read the data from the SD card. What is the flow rate of the Breeze pump? What size fuel line are you using?

https://www.holley.com/support/resources/#Fuel_Injection

https://www.amazon.com/UGREEN-Reader-Portable-Adapter-Windows/dp/B0779V61XB/ref=sr_1_2_sspa?crid=AZO2G9JUOBWC&dchild=1&keywords=usb+sd+card+reader+for+pc&qid=1599399239&sprefix=usb+sd+card+reader%2Caps%2C183&sr=8-2-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExQ0xQVTg5NVdES0FLJ mVuY3J5cHRlZElkPUEwNzc1MTg4VFhFMTlHMkZSRTc2JmVuY3J 5cHRlZEFkSWQ9QTAxMjEwMzg0SlIxQTg0TFRMM0Mmd2lkZ2V0T mFtZT1zcF9hdGYmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3R Mb2dDbGljaz10cnVl

Dave

[BradCraig]

Good info above. Start with the basics, does your TPS reading look right, IAC, etc? As Papa said, verify the fuel pressure with a gauge and that should be near 60PSI. A lot of guys use external regulators but you need to make sure the Holley "disc" is removed. You may also want to pull off your air filter to see if fuel is being delivered to all four bores. If not you may have a bad injector or one of the plugs has popped off the injector (known issue and you need to pull the cover off to verify). Also, these things are really sensitive to exhaust leaks and that will cause a false lean on the O2 sensor. Beyond that, it my just be a bad O2 sensor and that is easy enough to replace. I have never had to replace one but a lot of guys chew through those like candy. Scroll through the setup screens to make sure nothing inadvertently got changed too. Sorry for the stream of consciousness post... :-)

Are you doing Sniper timing control as well? This "sounds" like a fuel delivery issue.

[gkp200]

I liked the idea of only running 1 fuel line, so I went with the Breeze system. The pump is 255 size and the fuel line is big enough (I can't remember the size but it is set up for over 500 HP). I purchase the SD reader, so that will be here Tuesday. I will download the software shortly.

I'm not doing the sniper timing control. I will check on the injectors. I'll order another O2 sensor. I don't think I have an exhaust leak.

[Papa]

After a bit of reading, it looks like when using the Sniper in a returnless setup, an external regulator is used. So, let's assume that you are properly configured from what you described. We'll need to know what the fuel pressure is at the Sniper, so I'd also recommend getting a small fuel pressure gauge and installing it where your fuel line comes into the Sniper.

https://www.amazon.com/Earls-AT100199ERL-Ano-Tuff-Pressure-Adapter/dp/B006YH2JBG/ref=sr_1_6?crid=21JU99T75RU66&dchild=1&keywords=earls+fuel+pressure+gauge+adapter&qid=1599423008&sprefix=earl%27s+fuel+gauge%2Caps%2C177&sr=8-6

https://www.amazon.com/Marshall-Instruments-LS00100-Calibrador-combustible/dp/B01GQNVDDW/ref=sr_1_4?crid=2N8GVBXNC6WIF&dchild=1&keywords=liquid+filled+fuel+pressure+gauge+1%2F8+n pt&qid=1599423135&sprefix=liquid+filled+fuel+gauge%2Caps%2C190&sr=8-4

This thread has some useful information:

https://forums.holley.com/showthread.php?22153-Sniper-Plumbing

[gkp200]

Papa thanks. Fuel pressure gauge on order.

[Mark Reynolds]

The OEM style GM Filter/Regulator supplied is fixed at 58psi. The lines are all 06AN Braided Stainless Teflon Lined.