Holley Sniper EFI systems - Troubleshooting help page

[kiwigtx]

I have started this thread to gain extra knowledge, but to also assist those with the knowledge I have gained.
Consider this thread a tutorial with legs.....hopefully others will chime in with their problems or fixes - and share experiences.

My own issues probably started nearly three years ago but was only discovered a few weeks ago. I had been having cold start issues and rich-running condition for a while now.
Before we get too deep, my vehicle is a 1968 Dodge A100, with a BluePrint Engines 408.

I'll start off by saying there is nothing wrong with the engine, and I am not complaining here.

I did however learn by accident that I had one injector on my Sniper unit not squirting fuel into the barrel. I didn't actually know that all four barrels shoot fuel at pretty much all times......it's the rate and flow at which is the point of control. So, it turns out that if one injector is not firing or a barrel is running 'dry', then the one opposite it will try and compensate by injecting even more fuel into the engine to try and make up the difference.

Trouble is, all that does is make for a richer mixture than the engine can handle, and start causing other problems like plug fouling, O2 sensor fouling, back-firing, hard starting, rough idle etc. Anyone who experiences any two of those mentioned previously should take note and do something about the problem before driving any further.

I did the right thing (in my mind) and contacted Holley via the website and sent a message to the Technical staff. I did get a reply surprisingly enough....but it was like nearly a week later. By the time I had received the reply I had already engorged my eyeballs with so many YouTube clips, that I felt a lot taller and able to solve the problem myself. There are some really good YouTubers out there....and some not-so-good as well. I don't consider myself an expert by any means.....I do my videos for fun.

Here is a video I shot before touching anything....and I did this after I saw the first YouTube clip of how to diagnose the problem. I couldn't believe what I was seeing......



Now I was alerted to the problem, I thought I could have a crack at fixing this myself. Not as easy as it looks on the vehicle.... especially mine - close quarters inside the cabin.
First thing I did was re-install the fuel pressure gauge that I had removed soon after the original installation. Afterall, I had the correct parts, so why not? The engine is getting a constant 60psi fuel pressure even though I have a different pump location and setup.....already addressed that with another order to Summit Racing. The mods to the tank will probably happen later in the year when I get a bit more free time.

Here are some pictures of the first temporary fix to get the engine running better....

The most common problem is that the soft rubber plug which powers the injectors simply rattles off its postion....rendering the injector useless. The simplest fix that is out there is to close up the terminals and re-attach the plug, then secure the plug with a 5-cent cable tie. This stops the latching hook from coming away from the plug body.

The better solution (which is what I will do in a week or so) is to buy new moulded plugs that are much more robust, and redo the loom as far back as can be done without damaging anything else. I guess this is the part that Holley wish to remain a mystery.

I can't imagine there is anything inside the front compartment that will be too much of a mystery once I've had a go at it. The worst that can happen is that I end up buying a new Sniper.....or Sniper 2.

Here is a video after I had carried out the temporary fix last week.....



And now cold starting is easy....just like a modern normal car.

Here's a cold start just a day afterwards.....



Now that I know what the biggest problem is, and I have the parts coming....I feel a lot better about things.

Please feel free to share your thoughts or experiences here.

 

[bearman]

Seen this type of thing on big truck electronics. Seems that the clip isn't the best and from heat etc they work loose. So the tie wrap deal has come to be standard practice even after replacing the plug. Just for safety purposes we do it to all sensor plugs oil, water etc. Alot times the check engine light comes on and tells you low voltage then you look at it and fine it has worked loose. Allusion rear tail sensor also has this issue. Glad to see you moving forward your truck is very nice.

 

[Nxcoupe]

I will chime in on questions as well. For those that don't know, I'm a Holley EFI dealer and tuner. I've gone to Holley dealer training and have tuned a bunch on my dyno. Most of the issues I see are from guys not following instructions and not grounding properly. The positive and negative leads must go directly to the battery, no ifs ands or buts. The engi e must have a dedicated ground going from it to the battery. I'll help as I can and to the OP, great catch and fix.

 

[BeepBeepRR]

Glad you got it figured out. Worst issues I have had with Holley Snipers were the O2 Sensors would just randomly crap out. And then the Sniper would add fuel thinking the engine was running a lean condition. The Sniper would then dump fuel to combat the lean condition. Replaced 2 O2 sensors 2 separate installs. Replaced one with a Holley OEM 02 and the second was with a bosch equivalent. No problems with either system since.

 

[pnora]

One would think that the driver module losing contact with an injector would generate a fault code. I am not familiar with these systems compared to OEM EFI applications. Do these have any sort of diagnostics and fault code system?

 

[69ChargerR/TSE]

One would think that the driver module losing contact with an injector would generate a fault code. I am not familiar with these systems compared to OEM EFI applications. Do these have any sort of diagnostics and fault code system?

Unfortunately they don't, wish they did.
I had an a similar issue with an injector plug. I checked them all, and zip tied them all.

 

[69ChargerR/TSE]

I will chime in on questions as well. For those that don't know, I'm a Holley EFI dealer and tuner. I've gone to Holley dealer training and have tuned a bunch on my dyno. Most of the issues I see are from guys not following instructions and not grounding properly. The positive and negative leads must go directly to the battery, no ifs ands or buts. The engi e must have a dedicated ground going from it to the battery. I'll help as I can and to the OP, great catch and fix.

I'd like to check my tune, can you help?

 

[beanhead]

"NxCoupe" mentioned not following the instructions resulting in improper/poor installations, this is the absolute #1 cause of most of the problems with these units. However, even with a nice clean or even OCD-level install, problems can still pop up.

Some issues I have experienced with Sniper installs:
1... Weak (physically) injector connection, like Roger/Kiwi posted about. Injector wiring worked itself loose during operation. CL Compensation (fuel) showed abnormally high readings on the datalog as the computer was trying it's best to keep the A/F in line with only 3 injectors.
2... Bad RFI on old-school SBF engines specifically...but they can pop up on others as well. The symptoms were we couldn't get it to start and idle, and if it did is was short-lived and very erratic. Popping and farting like the distributor was misaligned. In the datalogs this presented itself as the ECU shutting down and restarting. In every case of the SBF problems, it was the distributor being so close to the ECU. A temporary test of some foil tucked over the cap confirmed the source. My one buddy fabbed up a small aluminum shield to mount in front of the throttle body on his. Sucked to have to do that, but it runs perfectly and he made it look pretty good anyway.

The good news is, Holley has rectified these and some other types of issues (FINALLY!) with the release of "Sniper 2".

My lowly advice to get started is, download the software for your particular kit and 'get learnded' on how to read and interpret those datalogs. It can be the difference between chasing your tail, and quickly diagnosing and fixing any potential problems.

The Holley EFI forum also has some sharp guys on there that know this stuff and like to help (Andy F can be found over there these days.)

 

[threewood]

Great thread. I'm glad you solved the issue without having to throw parts at it. Simple fix too.

My Sniper has been pretty trouble free since early 2021. The only issue I have had (after my car was out of my hands and in the hands of a car hauler) was the a/c pulloff was activated which bumped my idle up randomly. I reset it to 0 and no problems since.

Here is my Sniper thread...
Sniper Install

 

[69ChargerR/TSE]

Here is mine, I’m in the process of making OE looking stainless steel fuel line, I’m mocking it with plain steel

 

[kiwigtx]

Most of the issues I see are from guys not following instructions and not grounding properly.

^^^^Exactly this. I spent a couple of weeks reading the book before starting. It really is a new experience if you've never done one before.

Thanks @Nxcoupe ....I look forward to your support.

 

[kiwigtx]

"NxCoupe" mentioned not following the instructions resulting in improper/poor installations, this is the absolute #1 cause of most of the problems with these units. However, even with a nice clean or even OCD-level install, problems can still pop up.

Some issues I have experienced with Sniper installs:
1... Weak (physically) injector connection, like Roger/Kiwi posted about. Injector wiring worked itself loose during operation. CL Compensation (fuel) showed abnormally high readings on the datalog as the computer was trying it's best to keep the A/F in line with only 3 injectors.
2... Bad RFI on old-school SBF engines specifically...but they can pop up on others as well. The symptoms were we couldn't get it to start and idle, and if it did is was short-lived and very erratic. Popping and farting like the distributor was misaligned. In the datalogs this presented itself as the ECU shutting down and restarting. In every case of the SBF problems, it was the distributor being so close to the ECU. A temporary test of some foil tucked over the cap confirmed the source. My one buddy fabbed up a small aluminum shield to mount in front of the throttle body on his. Sucked to have to do that, but it runs perfectly and he made it look pretty good anyway.

The good news is, Holley has rectified these and some other types of issues (FINALLY!) with the release of "Sniper 2".

My lowly advice to get started is, download the software for your particular kit and 'get learnded' on how to read and interpret those datalogs. It can be the difference between chasing your tail, and quickly diagnosing and fixing any potential problems.

The Holley EFI forum also has some sharp guys on there that know this stuff and like to help (Andy F can be found over there these days.)

Thanks for the reminder on the other issues I have seen on different videos.

I still have some work to do to identify any other potential problems.
While my engine is running ten times better now, I'm sure there is room for improvement.

I did see one guy solve the RFI problem by using small electronic type ferrites around certain power cables - they reduce interference and noise significantly just like the do with household appliances like TV's. And they are cheap enough to buy and easy to install.

 

[threewood]

Well, you had me paranoid enough to look....all 4 of my injectors are firing.

 

[64fury74charger]

Timing is everything, lol…I have been studying the Holley Sniper forums as well after some interesting issues with my sniper. Today I took the air cleaner off and the answer was obvious.

Pulled the cover on one side and I chose option number 2 and the new unit and regulator should be here by Thursday according to Summit. I don’t know how well the pictures will show the difference, but my wife pointed it out almost immediately and she was there to turn the key on/off if needed but never got that far.

I could try to repair or bandaid this one but my time is worth something too and I have already done so much wiring on this car that has really made a huge difference I am not going to mess with it.

 

[kiwigtx]

Timing is everything, lol…I have been studying the Holley Sniper forums as well after some interesting issues with my sniper. Today I took the air cleaner off and the answer was obvious.

Pulled the cover on one side and I chose option number 2 and the new unit and regulator should be here by Thursday according to Summit. I don’t know how well the pictures will show the difference, but my wife pointed it out almost immediately and she was there to turn the key on/off if needed but never got that far.

I could try to repair or bandaid this one but my time is worth something too and I have already done so much wiring on this car that has really made a huge difference I am not going to mess with it.

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Nice installation....and you have a bit more space to play with.

So was it loose connectors only....or a bad injector?

It is easy to test each injector by using a pair of small jumper leads and a 12 Volt supply.

 

[64fury74charger]

Nice installation....and you have a bit more space to play with.

So was it loose connectors only....or a bad injector?

It is easy to test each injector by using a pair of small jumper leads and a 12 Volt supply.

I was initially prepared to test the injectors and look at the rest but my decision was to go with the upgrade and when I put the new unit on I am going to clean up some more wiring and separate and insulate pretty much everything I can.

This also explains my average mileage being around 10 overall instead of 14 to 15 mpg. I have worked very hard to sort out and separate all the wiring and I have a dedicated relay for a clean 12 volts to the magic pink wire. New wires, trying out the NGK plugs as well. I have the hyper spark system ready to go and now maybe I can get that in as well.

I try to make my upgrades clean and easy to access or service when needed and dependable. Takes less time to do it right the first time and know what you’re running on.

 

[kiwigtx]

Plugging in today when I get sorted out a bit more.

 

[kiwigtx]

Finally had a chance to play a bit more.....downloaded the Firmware update and was able to get online with the Sniper in my truck.
I shot a bit of video to give an overview of some of the stuff unlocked by plugging in with a computer. Looks like I have a lot of stuff to play with and adjust here.

 

[64fury74charger]

Looks like you’re going to discover some new ways to wake up the Sniper. I just got home from work and my Sniper 2 is now in my hands. I would like to hook a laptop to mine, but I don’t currently have a functioning laptop.

I am looking forward to this weekend and changing out the Sniper and I also got a nice fuel pressure regulator. Aeromotive seems to have decent parts and that’s where I got the gas tank with the pump. Keep us posted on your laptop adventures.

 

[threewood]

How did you do your firmware update? I just did mine but it took me forever to figure out, even after watching the video. And it took me a few tries at saving a configuration to the SD card and finding it on the handheld. This stuff needs to be more user friendly.