Holley sniper issues

[Kris 90]

I installed a Holley sniper system on my car and I’ve been fighting it for 2 weeks now. It will crank and run great for 2-15 seconds then die. It will flood itself out and won’t start back, just crank and crank. I had the pink ecu signal wire connected to a bullet connector on the passenger side that has has a green wire with red stripe. At the bullet connector I get 12v on run and 10-12v while cranking. I though I had a timing or distributor issue but I disassembled it tonight and it’s perfect. I decided to connect the pink wire directly to the battery to test if this was the issue after doing hours of reading and research online and it fired right up and ran perfect for 2 minutes when I finally killed it. It also started back perfectly each time I tried it afterwards. So my question is where should I connect the pink signal wire to since the bullet connector doesn’t seem to work even though the voltage seems correct. It needs to be a 12v crank and 12v run and dead when the key is off.  

[aslanefe 320]

I have the pink wire and red with thin black wire connected to the bullet connector with green and red wire on voltage regulator; it has been working for over 2 years.

[aslanefe 320]

As far as I remember when engine dies, it should cut the pump and injectors off; if it is flooding, there must be an other problem.

[Kris 90]

The only thing I can think of or find is possibly interference coming through the log wiring that’s affecting it at the bullet connector. My voltage at that connector is fine and the sniper display never flickers at all. It will just start and die when connected to that connector. If yours is working with that there’s no reason mine shouldn’t. What think red and thin black wires are you talking about? If you have any pictures of how you have that hooked up too that would be great. I’m considering running another relay to power the switched 12v ecu power if I have to. I wanted to see what others with 69 mustangs have done with their sniper systems for this wire before I do that though. 

[Rich Ackermann 172]

21 hours ago, Kris said:

I installed a Holley sniper system on my car and I’ve been fighting it for 2 weeks now. It will crank and run great for 2-15 seconds then die. It will flood itself out and won’t start back, just crank and crank. I had the pink ECU signal wire connected to a bullet connector on the passenger side that has has a green wire with red stripe. At the bullet connector I get 12v on run and 10-12v while cranking. I though I had a timing or distributor issue but I disassembled it tonight and it’s perfect. I decided to connect the pink wire directly to the battery to test if this was the issue after doing hours of reading and research online and it fired right up and ran perfect for 2 minutes when I finally killed it. It also started back perfectly each time I tried it afterwards. So my question is where should I connect the pink signal wire to since the bullet connector doesn’t seem to work even though the voltage seems correct. It needs to be a 12v crank and 12v run and dead when the key is off.  

I believe the pink wire should be connected to the red/green striped #904 ignition start/run wire. This wire has power in both the start and run (on) positions. 

Other causes for the engine shutting down after a short time, might be....

What is your AFR (O2 sensor) reading at idle? If the AFR value is not fairly steady on your hand held display then you have an exhaust leak before, at, or right after the O2 Sensor. At idle any leak, even a pin hole leak, in these areas or at the exhaust manifold will cause ambient air to be drawn into the exhaust causing a erroneous lean condition reading in the Sniper's closed loop system. The Sniper ECU will try to compensate by adding in more fuel. This in turn, will make the AFR too rich, so the ECU then reduce the fuel to lean it up, and the Lean/Rich cycle begins again. All this will begin to foul your plugs and you will have high carbon (unburned fuel vapor) out your tailpipe(s). Check your plugs for black carbon build up. If so, then find that leak or leaks and stop them all. I weld the O2 sensor bung to the exhaust pipe. The O2 sensor bung, rubber gasket, and clamps just leaked too much. I had a friend put some sort of small smoke bomb in his tailpipe and hooked up his ShopVac to the tailpipe to force air and smoke into the pipe and blow smoke out any exhaust leak holes.

Higher RPMs usually will not cause this issue as the exhaust volume will force itself out of any leaks.

Second thing to check... The voltage reading on your hand held. The number should be fairly steady at 14+ amps, if not your alternator is not able to keep up with the your cars electrical demand, and/or your wiring from the alternator to the battery is large enough to carry enough current to and thru the battery, and make sure the wire to the ECU is not too thin or is damaged. Holley Sniper says 12 AWG minimum direct from the battery (and has a 15 amp fuse inline). Fluctuating and/or Low voltage will cause the ECU to shutdown if the voltage gets below 12v to protect itself and it may eventually cause the sniper ECU to electronically fail.

Check you fuel pressure at the sniper inlet. If I recall correctly, Holley Sniper says 60lbs.

The PDF I have attached is a Motor Trend article about the effects of exhaust leaks on the O2 sensor and Air Fuel Ratio on a EFI System. I found it to be an eye opener.

Ask me how I know this... Good Luck!

How an Exhaust Leak Affects Wideband-O2 Sensor Readings.pdf

[aslanefe 320]

18 hours ago, Kris said:

What think red and thin black wires are you talking about? If you have any pictures of how you have that hooked up too that would be great.

It is one wire, red with thin black (or an other dark color) stripe on it. I connected a male bullet connector to the pink wire and the red with thin black wire and connected them to the female bullet on voltage regulator. Sorry I don't remember exactly where the red with black wire goes, might be a wire for Duraspark 2 ignition or the Prius EPS I installed;  encased all the wires in shields so I can not follow that wire without undoing all clean-up/hiding the wires in shield etc.

[Kris 90]

My bullet connector off the voltage regulator is green with a red stripe. That’s what I was using and the voltage seemed adequate but it would run then die. When I connect pink wire straight to the battery it runs good. The Holley only has a red wire that goes straight to the battery positive. Unless your using the additional connector for other inputs / outputs. If you have another wire it must be from a different device you have. 

[Rich Ackermann 172]

1 hour ago, Kris said:

My bullet connector off the voltage regulator is green with a red stripe. That’s what I was using and the voltage seemed adequate but it would run then die. When I connect pink wire straight to the battery it runs good. The Holley only has a red wire that goes straight to the battery positive. Unless your using the additional connector for other inputs / outputs. If you have another wire it must be from a different device you have. 

I can't explain why it been working for years, but the green/red wire (904 on the Ford wiring diagram)  is correct for constant voltage during the start and run ignition switch positions.

Assuming you have your factory ignition/ Prove-out wiring is intact, The correct wire to connect the Pink ECU wire to is one that provides constant 12v during start and run ignition switch positions. The red/blue striped wire (32 & 32A) on the Ford wiring diagram) does not, it only has power in the start position. The green/red stripe wire (904 on the Ford wiring diagram, not to be confused with the #16 red/green striped (or sometime called the pink #16A resistance) wire depending on which of the two wire diagrams you look at) has power when the key is in the start/prove-out and run ignition switch positions, and that's the one to connect the pink wire to. Also I suggest tapping this wire as close to the ignition switch plug and run it to a relay and have the relay tripped by the red/green wire and supply the 12v to the pink wire to the ECU. This will take the additional 12v current draw to the ECU and ignition box (if you have an MSD or Hyperspark ignition box) off the factory green/red wire  and ignition switch and insure that the pink wire is getting 12v directly from the battery.

Here are a few wire diagrams showing the Start/Prove out for a factory tach and non-tach car.

[Kris 90]

I went through my exhaust system and found the Holley o2 sensor flange to be the only thing leaking. It was leaking all the way around the gasket. I took my headers off and welded the plate directly to it. Went back through and found no leaks using the shop vac and soapy water method after I reinstalled the header. I didn’t get a chance to start it tonight as it was getting late and my battery was a little low from cranking. I’ll put it in the charger tomorrow and see how it works now that there isn’t an exhaust leak directly at the o2 sensor. I have a factory wiring harness. I’m running a msd box and msd pro billet distributor. Non of that is tied in with the pink Holley wire. 

[Rich Ackermann 172]

44 minutes ago, Kris said:

I went through my exhaust system and found the Holley o2 sensor flange to be the only thing leaking. It was leaking all the way around the gasket. I took my headers off and welded the plate directly to it. Went back through and found no leaks using the shop vac and soapy water method after I reinstalled the header. I didn’t get a chance to start it tonight as it was getting late and my battery was a little low from cranking. I’ll put it in the charger tomorrow and see how it works now that there isn’t an exhaust leak directly at the o2 sensor. I have a factory wiring harness. I’m running a msd box and msd pro billet distributor. Non of that is tied in with the pink Holley wire. 

You might want to pull a plug as see if there is any carbon build up. If there is, better off taking time to clean them all. If you have not done so, I would strongly recommend installing a relay connect it to pink wire and to the battery for 12v and use your red/green ignition wire to trip it. That wire was not meant to carry a lot  of current and its not a clean power source to be used with the ECU. You will know if you have a power issue by looking at the voltage number fluctuation on the hand held. below 12v even for a moment is bad for the ECU electronics. Good Luck

[Kris 90]

I pulled all the plugs already and cleaned them yesterday. There were all black with carbon buildup. I’m pretty sure I’m going to install a relay so the voltage will have less chance of fluctuating. When I metered the green/red wire with a fully charged battery, it still has fluctuation when cranking. It was still within the Holley suggested range but it’s more of a drop than straight off the battery so a relay should help with that. 

[Kris 90]

I spent 2 hrs on the phone with Holley tech support for a second time and they determined my idle air controller is bad. They’re shipping me another one so hopefully this will fix my problem. 

[aslanefe 320]

35 minutes ago, Kris said:

I spent 2 hrs on the phone with Holley tech support for a second time and they determined my idle air controller is bad. They’re shipping me another one so hopefully this will fix my problem. 

That is a common failure, I had mine replaced too. Also, the temp sensor that comes with the kit is an other problem part; mine was not reading correct (compared to infrared measurement), had to buy an other brand (was AC Delco I think) which reads within a few degrees of infrared measurement.

[Kris 90]

My tps sensor was bad and wouldn’t zero. They replaced that and still had issues. The guy today had me to quite a bit more tests and he was a little stumped too. He finally had me turn the idle screw in and uncap the vacuum port on the back so it could get more air. Did that and checked my idle air reading and noticed it wasn’t working properly. Hopefully this will fix my issue. He was going to send me a whole new unit but they are on back order until end of august- September. He said due to supply shortage they can’t get the parts to make any new ecu’s. 

[Kris 90]

My new idle air controller came in today. Put it on and still have the same problems. They only way it will stay running is if the idle air screw is bottomed out. Once it’s running if you adjust it more than a 1/4 turn out it falls on its face and dies. Talked to Holley tech support for another couple hours and they think something internal is defective. They’re sending me a shipping label so I can send it back for them to go through and determine the issue. Hopefully it’s something they can fix as they don’t have any replacement units to send me. They are on back order till the end of August. 

[Kris 90]

What spark plugs are you guys running with your sniper setups? I currently have Autolite 45 copper plugs. They are resister plugs like they are supposed to be and I have MSD super conductor wires. I finally got it to run and idle by running it in closed loop but it still runs rich. The tech guy I spoke to at holly thinks I need to run a different plug. 

[Rich Ackermann 172]

On 7/16/2022 at 4:33 PM, Kris said:

What spark plugs are you guys running with your sniper setups? I currently have Autolite 45 copper plugs. They are resister plugs like they are supposed to be and I have MSD super conductor wires. I finally got it to run and idle by running it in closed loop but it still runs rich. The tech guy I spoke to at holly thinks I need to run a different plug. 

Kris, sorry for the delayed response.

I have Motorcraft ACF 42CA Plugs and Moroso Ultra 40 Race Wire sleeved 8.65mm 40 ohms.

Rich

[Kris 90]

Thanks. That’s basically what I’m running. I have the Autolite equivalent of the Motorcraft plugs your using. I’m using msd super conductor plug wires that are supposed to be great at reducing emi. I think my O2 sensor is part of my problem along with it running rich overall. The car will idle in closed look but will eventually start to run rough when the plugs foul due to running rich. When I’m open loop it will only run for 30 seconds or so and then die. I’ve fully checked the exhaust and intake systems for leaks and have corrected them all. I used the shop vac with soapy water method and also used a smoke machine to pump smoke into the exhaust and intake and have no leaks. I’m going to talk to Holley again today and see what hey say. I have a 302 that is bored over but I’ve been keying it in as a 302 on the handheld. The tech at Holley said that’s fine. To me if that was the issue it would be running lean not rich. 

[det0326 172]

A bad O2 sensor will cause the issues you are describing, I have seen O2 bad right out of the box especially China ones.   They are some test procedures on line to check O2 sensors but I don't know how reliable they are.

[aslanefe 320]

Does your Sniper temp sensor work correctly? Have you watched the coolant temp on Sniper display? Wonder if temp sensor is registering low and keeping the Sniper at choke setting?

[Kris 90]

The temp sensor from what I can tell works. Not sure how accurate it is though. I will take a look at it and verify. Thanks