Holley Sniper 2GC to 2F Install using Mosley Motors adapter

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derail said:
One more thing I would suggest. Look down the throat while it's running and make sure that both injectors appear to be firing evenly. It should be apparent. Especially try to do this while it's running rough and going lean. Each time you do something significant, (like making sure the injectors are 100 percent secure) start over with a new configuration. Act like you just pulled it out of the box. Although a lot of your videos show it not up to operating temp, it has still learned some bad habits from trying to keep it running during the troubleshooting process. Those bad habits bleed over and will make it not run correctly even if you've corrected the problem. Also, stick with it. You'll get it. And it can/will be rewarding. I had a lot of problems in the first year. It was a completely new platform that I had no experience with. I basically daily drive mine and haven't touched a thing in almost 3 years after finding the "sweet spot."
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Here is some video of the throttle body. The first running properly, the second 2 is when it acts up. When acting up, the fuel flow seems to pulsate.

But what is causing this sudden occurrence with all adjustments are the same? You can later go back to the truck restart, drive and all is good…..until it isn’t.



Running poorly



Running Bad 2 - https://youtube.com/shorts/JCHBXdNzRpo?si=03IOXz8RWrHYUSYL
 
Damn, you’ve been thru a mess of testing and reviewing…I’d give Holley Tech a call and just get some possible inside data they may have about the very few Snipers that act this way.

Who knows…they may say “ Oh? We have had this happen ..you need to …XXX.. and it will solve your issue”. DAMN you’ve done almost everything else at this point
 
FORGOT TO ADD;
Holley tech is busy all day long and an average call has a 30-40 minute call time…they HAVE the worst music on hold you could possibly ask for. It is the same repeating 8 bars of s#!t I’ve ever heard. The message also counts down…” you are caller 16”. Then it starts all over

I suggest have something your working on near the phone, put it on speaker and do what you are doing. As it gets down to “ you are caller 2”, get your stuff ready. If your tech seems like it’s not getting the point across, ask for another more familiar with the 2300.

I’ve been thru that about 8-9 times initially with my IAC adjustments… a tech named RON helped me the most..FWIW
 
This seems wonky for sure.

Also, I still haven’t seen a video where the adjustment procedure was fully completed, or there were helpful videos but wrong sniper screen was showing. There always seems to be at least one red flag that keeps me from calling Holley

There are lots of posts (if you start googling IAC) that show you how to set the idle speed by blocking the IAC intake.

I would recommend doing this, and as soon as it is set, unplug the IAC

Then show us what happens. If the IAC is the problem it should mysteriously clear up (according to internet)

Then call Holley
 
High five for not putting it up for sale yet!
 
FJ60Cam said:
High five for not putting it up for sale yet!
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Well, unfortunately it is hard to sell it with this issue and I can’t fix it, so I am kind of stuck at the moment!

Here is a recap of the week’s efforts:

Checked for vacuum leaks.
Rerouted some of the harness to keep from other wire.
Checked timing.
Installed original IAC motor.
Retired the tach input.
Downloaded the newest Sniper tune from the Holley Tech line.
Installed new Fuel Pump and post pump Filter/Regulator, the pre filter was changed during the beginning of this process.
Reran Positive and Negative Sniper Harness wires to assure clean power.
Was on the phone with Holley for over an hour further tuning the IAC when it acted up, now waiting to try it again and call back.

Each one of these resulted in the same outcome, runs great………until it doesn’t!
 
desmocruiser said:
Well, unfortunately it is hard to sell it with this issue and I can’t fix it, so I am kind of stuck at the moment!

Here is a recap of the week’s efforts:

Checked for vacuum leaks.
Rerouted some of the harness to keep from other wire.
Checked timing.
Installed original IAC motor.
Retired the tach input.
Downloaded the newest Sniper tune from the Holley Tech line.
Installed new Fuel Pump and post pump Filter/Regulator, the pre filter was changed during the beginning of this process.
Reran Positive and Negative Sniper Harness wires to assure clean power.
Was on the phone with Holley for over an hour further tuning the IAC when it acted up, now waiting to try it again and call back.

Each one of these resulted in the same outcome, runs great………until it doesn’t!
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Does your battery/alt/coil pass testing?
 
Jdc1 said:
Does your battery/alt/coil pass testing?
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Battery is good, alternator is new, both show a charge after idle in the handheld of 13-14.5 volts.

Have a new Dist Cap, Rotor, and coil on the way from DUI, just to be thorough.
 
Spent a couple of hours (not including on hold time) on the phone with Holley the past couple of days:

I updated the profile on the SD Card to the newest, reran a few wires to make certain of clean power and no RFI, changed the fuel pump and forward filter/regulator, confirmed no vacuum leaks by covering up the IAC and getting the idle below 200 before it died, more time setting the IAC (which they feel isn’t responding correctly and recommended a new IACValve/motor. When I let them know I already had replaced it and have the same outcome with both the original and the new one, they were out of suggestions, other than to try a new Coil, Dist Cap, Rotor to rule out an issue with the DUI that occurs at temperature and corrects itself after 2-10 minutes.

They emailed me a the information to box it up and send it back for testing, which only takes 3-4 weeks.

Open to any additional suggestions to try, not a fan of waiting a month or so.

Thanks again for all the help and hanging in on this thread I have managed to Hijack!
 
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Just because a part is new doesn’t mean that’s it’s good. When it’s acting up- what does your multimeter say is happening at the battery and the alternator. Ignore the Sniper, confirm that this is a healthy engine.

Also:

IMG_0490.webp
 
desmocruiser said:
Battery is good, alternator is new, both show a charge after idle in the handheld of 13-14.5 volts.

Have a new Dist Cap, Rotor, and coil on the way from DUI, just to be thorough.
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I just had a weird issue on a 2F/Sniper conversion. Engine was running nicely but idle was a little
rough. Power was good through the middle of 3rd gear but at the top of 3rd and into 4th was cutting out.

It turned out to be a combination of 2 things- 1 -brake booster pushrod was adjusted too long and rear brakes were dragging after a few miles and 2- DUI HEI cap was bad.
IMG_0469.webp
IMG_0470.webp
 
Jdc1 said:
Just because a part is new doesn’t mean that’s it’s good. When it’s acting up- what does your multimeter say is happening at the battery and the alternator.

Also:

View attachment 4119502
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The voltage never changes other than the increase with RPM.

There’s always a possibility the DUI/HEI coil/cap/rotor could be going bad, just have never seen one work fine and fail and correct itself so consistently. My experience has been a high temperature failure remains failed until cooled significantly.

In this case, the cause typically resets itself after 2-10 minutes and you are able to drive until it fails again, maybe minutes, could be miles, could take possibly a few drives over a couple of days.

Thanks for sharing, please keep up the suggestions!

Signed-Perplexed!
 
Jdc1 said:
I just had a weird issue on a 2F/Sniper conversion. Engine was running nicely but idle was a little
rough. Power was good through the middle of 3rd gear but at the top of 3rd and into 4th was cutting out.

It turned out to be a combination of 2 things- 1 -brake booster pushrod was adjusted too long and rear brakes were dragging after a few miles and 2- DUI HEI cap was bad. View attachment 4119508View attachment 4119509
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I continue to be optimistic in the end it is not a Sniper failure, I have endured plenty of grief being the biggest fan and supporter in the local group!

Hope the ignition components arrive tomorrow and we will see!
 
I did establish one thing after a long week battling my 40!

It’s Miller Time!
 
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I assume you’re changing the DUI module as well?
 
IMG_6988.webp
 
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