Holley sniper problems (1 Viewer)

[Advrider639]

My 40 has been sitting for some time…. Just took it for a spin and when idle the AFR reads 9.6, then will spike to 35.6 every 30 seconds or so then catch its self with extra rpm to keep running. IAC at 4% but drifts as well…

When on the road it bogs down bad on acceleration.

She ain’t happy!

 

[Catching Neutral]

No idea but I hope you don’t mind me jumping in on this thread.
I have had my sniper for almost 2 years without problems. It started running rough especially under throttle two days ago. New O2 sensor ordered. Here are the numbers.

 

[Advrider639]

I had mine stick at high AFR once, new O2 sensor cleared it right up.

Maybe mine needs a new one again….

 

[Catching Neutral]

I am changing fuel filters tomorrow. The sensor is now scheduled for delivery Monday.

 

[Steamer]

Try disabling the "Closed Loop". I believe it takes the O2 sensor out of the circuit and runs on the last settings. If it runs better, then it's probably a faulty O2 sensor and it can get you by till it's replaced.

 

[jembourbe]

Could your idle RPMs be dropping low enough that the system thinks it's in crank mode (where it opens the iac)?

Does sniper let you look at those settings?

 

[Advrider639]

Disabling closed loop made all of the difference.

This will be o2 sensor #3…. I’ve got headers 3 into one with a Y pipe around the oil pan area. Sensor is placed just downstream. Could it be too far away from combustion?

 

[A10Driver]

Check for a vacuum leak, any leak will create issues in the system.

 

[Advrider639]

Vacuum is on the low side 17”, but steady.

Looks like I have an exhaust leak at the y pipe. I’ll put some dope on it to see about a better seal.

 

[Steamer]

Could it be too far away from combustion?

Looks like I have an exhaust leak at the y pipe

Exhaust leaks upstream of the sensor is bad.
I think being too close can be an issue but not too far away. I’ve gone through quite a few sensors. I moved mine further downstream believing it was getting too hot. I used a 45 deg bung and added a bung extender. All my faulty ones were sooted up bad and I had poor luck in cleaning them. However, since the head was rebuilt, it’s been running great on the only one sensor I was able to clean. I do keep a spare sensor on board along with the wrench.

 

[Catching Neutral]

I started it this morning. Idles good. Solid, steady vacuum @18. Disabled Closed Loop and took it for a short drive. AFR remains around 30 and the IAC which normally sits at 3 or 4 is 11 to 14. Drives fine with no stumbling but I can definitely smell the unburned fuel. The soft top creates a Venturi which brings all the fumes into the cab.
(hence the catalytic converter in my future). We’ll see Monday evening when the new sensor arrives if that is the problem.
RE the post below. I did take the air cleaner off and noticed a nice even mist of fuel spraying in both barrels of the throttle body.

 

[POTATO LAUNCHER]

I encountered similar issues with a customers 40 I installed a Sniper on couple of years ago that recently reared it's ugly head. Fuel tank has Aeromoter pump with custom sump. It had decent idle but lacked power unless feathered, like it was starving for fuel. Found the vacuum advance diaphram had failed and though it was the culprit. Replaced the distributor and set proper timing. Fired right up but had the exact symptoms. After hours of troubleshooting, resetting parameters on the touch screen there was no effect. So I went back to basics. Fuel, Spark and Air. All these were present but something was amiss. Looking down the throttle body I realized the right / inbord ventury had very little fuel spraying, burping the throttle had little to no affect. The left / outboard ventury was spraying a consistent mist of fuel the circumference of the bore. This is a little troubeling considering Holly's customer service and 3-4 week turnaround on warranty work I dind'nt have the luxury of time.

So I removed the front of the fuel injector cover and tested the connections to the fuel injectors which had good voltage. Next suspect was the injector istelf. I removed it and tested it with 12v power and it clicked / opened every time without fail. I assumed it was clogged so I went to search for a suitable replacement from off the shelf. They are available from Holly and several specialty shops but nothing fast like same day. I cleaned the injector in my ultrisonic heated cleaner using water based cleaner. After the cleaning I dried it off and tested again with 12v power, it was still working correctly and I blew it out with compressed air and injector cleaner. I did the same on the throttle body where the injector seats in the base. It had a good spray pattern in the ventury the full circumference of the bore now.

Granted this is a unit that I installed several years ago but the first with this type of problem. It makes perfect sense now with the fuel delivery problem. If your Sniper is under the warranty period proceed with caution. There isn't really anything you can damage or screw up irreversivbly.

Reassembeled everything back being careful to lube the O-Rings with light oil. Turned the ignition on to get the fuel flowing without starting to assure no leaks.
Turned the key and it fired right up, idled like a dream and had no hesitation under a load.
Long story short here, if i have another issue with a Sniper the injectors will be my primary trouble shooting technique. Without the fuel system working properly as a key component on internal combustion engine, everything gets out of sink. The Sniper computer was over fueling through one barrel no matter what resetting the touch screen setup did. The one area that really helped in this instance after injector replacement was setting the accl fuel inrichment to around 15#. The is very little raw fuel smell while sitting at idle or heavy footed acceleration.

This may not be the answer to all Holly Sniper issues but it was a success for me. My advice is look into your throttle body while running for a consistant mist of fuel in the ventury. I hope this helps some folks with similar issues in the future. It takes little effort to verify smooth equal fuel flow in both throttlebody ventury bores.

 

[cruisermatt]

I encountered similar issues with a customers 40 I installed a Sniper on couple of years ago recently reared it's ugly head. Fuel tank has Aeromoter pump with custom sump. It had decent idle but lacked power unless feathered, like it was starving for fuel. Found the vacuum advance diaphram had failed and though it was the culprit. Replaced the distributor and set proper timing. Fired right up but had the exact symptoms. After hours of troubleshooting, resetting parameters on the touch screen there was no effect. So I went back to basics. Fuel, Spark and Air. All these were present but something was amiss. Looking down the throttle body I realized the right / inbord ventury had very little fuel spraying, burping the throttle had little to no affect. The right / outboard ventury was spraying a consistent mist of fuel the circumference of the bore. This is a little troubeling considering Holly's customer service and 3-4 week turnaround on warranty work I dind'nt have the luxury of time.

So I removed the front of the fuel injector cover and tested the connections to the fuel injectors which had good voltage. Next suspect was the injector istelf. I removed it and tested it with 12v power and it clicked / opened every time without fail. I assumed it was clogged so I went to search for a suitable replacement from off the shelf. They are available from Holly and several specialty shops but nothing fast like same day. I cleaned the injector in my ultrisonic heated cleaner using water based cleaner. After the cleaning I dried it off and tested again with 12v power, it was still working correctly and I blew it out with compressed air and injector cleaner. I did the same on the throttle body where the injector seats in the base. It had a good spray pattern in the ventury the full circumference of the bore now.

Granted this is a unit that I installed several years ago but the first with this type of problem. It makes perfect sense now with the fuel delivery problem. If your Sniper is under the warranty period proceed with caution. There isn't really anything you can damage or screw up irreversivbly.

Reassembeled everything back being careful to lube the O-Rings with light oil. Turned the ignition on to get the fuel flowing without starting to assure no leaks.
Turned the key and it fired right up, idled like a dream and had no hesitation under a load.
Long story short here, if i have another issue with a Sniper the injectors will be my primary trouble shooting technique. Without the fuel system working properly as a key component on internal combustion engine, everything gets out of sink. The Sniper computer was over fueling through one barrel no matter what resetting the touch screen setup did. The one area that really helped in this instance after injector replacement was setting the accl fuel inrichment to around 15#. The is very little raw fuel smell while sitting at idle or heavy footed acceleration.

This may not be the answer to all Holly Sniper issues but it was a success for me. My advice is look into your throttle body while running for a consistant mist of fuel in the ventury. I hope this helps some folks with similar issues in the future. It takes little effort to verify smooth equal fuel flow in both throttlebody ventury bores.

I have a brand new Sniper here leaking fuel out of the injector body externally, and in the same boat.
I think their QC on injectors is not great.
I think all the sniper injectors are the same 100lb/hr, (which is bigger then any OEM gasoline injector) and have a LS3/LS9/LSA-architecture.

What I came with for a quick test. LSA injector, 60lb/hr. Should drop-in.
Will have 160lb/hr vs 200lb/hr total injector but that should be plenty for a F145, going to try it and see how it goes. Thr injector data in the tune will be off but closed loop should compensate enough. Will know in the next day or so.

Bosch 62659 available pretty quickly thru Rock Auto or Amazon for about $60

 

[POTATO LAUNCHER]

I have a brand new Sniper here leaking fuel out of the injector body externally, and in the same boat.
I think their QC on injectors is not great.
I think all the sniper injectors are the same 100lb/hr, (which is bigger then any OEM gasoline injector) and have a LS3/LS9/LSA-architecture.

What I came with for a quick test. LSA injector, 60lb/hr. Should drop-in.
Will have 160lb/hr vs 200lb/hr total injector but that should be plenty for a F145, going to try it and see how it goes. Thr injector data in the tune will be off but closed loop should compensate enough. Will know in the next day or so.

Bosch 62659 available pretty quickly thru Rock Auto or Amazon for about $60

View attachment 3461522

Good find Matt. Online sluthing found similar results for me. The only difference I can see is the O-Ring differences. Maybe carefully transfer the Holly O-rings to the replacement will resolve this?
It would be great to find an easy off the parts store shelf part that will be readily available for those of us that regularly do long haul trips in these old trucks. Please post up with your results.

 

[Firemedic831]

Summit has the injectors. But normally the injectors are fine it’s the connector that comes loose. They redesigned all of this on the sniper 2 . Now I wonder. If you could use the new sniper 2 injector and cut the old connector off and add the new style hmm

 

[cruisermatt]

You can do whatever you want if you put the right injector data into your tune.

 

[Firemedic831]

Also make sure you check the fuel pressure . The regulator has a little screen and can get clogged very easy . And if you are running at 30 That is extremely lean Not rich Lower the number the richer you are

 

[cruisermatt]

The problem with using two 100lb/hr fuel injectors instead of, say, six 15-20lb/hr injectors which is what a F or 2F would have it if it was port-injected, is that those two big injectors are running at only 5-10% of capacity during normal driving which means they'll have pretty poor resolution when compared to a regular injector.

This is a big reason why port injection is inherently better then TBI.

I would not be surprised at all if replacing both sniper injectors with smaller lb/hr and correcting the data in the software would net smoother idle and low RPM drivability.

 

[POTATO LAUNCHER]

Exactly right Matt. These old motors don't have huge fuel demands so a comparable injector with the correct body size to fit under the fuel rail / cover is paramount. Holly uses a pseudo proprietary in house formula for their products. That doesn't mean there isn't a similar product that doesn't fit or perform the correct function that the engine is requiring. One thing that could limit compatibility is the plug design, but that can be upgraded to adapt to a suitable alternative.
All this can be useful for future Sniper issues. After all IH8Mud is famous for finding and sharing solutions to common problems.

 

[cruisermatt]

There are tons of options out there for the LS3 injector dimensions