Holley EFI Leaning Out / Drivability Issues

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Just wanted to check in and see if someone can provide some insight into the Holley Sniper system here --

Over the last two mornings, I've had severe drivability issues with my Sniper EFI system. It starts with dying at idle coming off deceleration in gear, and eventually evolves into failing to maintain an idle due to excessively lean fuel trims (A/F ratio value on the handheld unit is ready 20-35%+, worse under load).

I figured I'd just throw a fuel filter at it while it was in the shop. 5 minutes in and out, and she was running good.
Got home, parked it, and woke up the next morning -- same thing. Choking / sputtering / dying. A/F values near 20-30% again.

I don't have the EFI dongle, so I can't do any of the techno-wizardry recommended online, but if someone could tell me if I'm on the right track here:
If I disable closed-loop fuel control via the hand-held display (assuming my best mixture / fuel map hasn't been corrupted by the above), would that isolate the wide-band HO2S as being at fault if the EFI system were then to run as normal?

I'm a bit leery of the sensor primarily due to the astronomical fuel trims, and the fact that the past few mornings have been colder than normal. So I'm suspecting possible thermal shock at cold-start may have wiped it out, but don't yet have the tools to verify it and condemn the sensor (EFI dongle is in the mail).
Appreciate any advice.
 
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Got back to the house. Tried firing it up - fuel is stuck at 35.6% at all times... seems like a hard fuel fault rather than input sensor issue?

Disabled Closed Loop operation, no change... tells me the wideband HO2S is probably not to blame -

Inspected the barrels of the EFI unit and found the passenger-side was not receiving fuel during key-on cranking.
Removed the front cover of the Sniper EFI unit and found the passenger-side injector connector partially unseated. Unfortunately Holley seems to have found the cheapest zero-retention connectors for these... so zip ties had to do the job. NOT thrilled about seeing poor build quality like this.
EFI3.jpg

EFI6.jpg


Fired it up and still zero fuel from passenger side injector.

Seeing as how I can't get a noid light set in here to verify injector pulse / signal, how does one go about diagnosing this? Just measure the resistance of the injectors? Swap injectors to see if the issue follows the injector? Disconnect fuel pump source voltage wire and crank to check injector pulse? Or is the Holley software smart enough to shut down injector pulse if it doesn't see fuel pressure?

Interested in seeing if I can source any aftermarket injectors or higher-quality connectors for these as well.
 
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cruisermatt

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what are the odds your fuel system is garbage ?
 
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what are the odds your fuel system is garbage ?
I would hope very slim. I've got new hard and soft lines from the tank to the EFI unit. I'm using two brand-new Wix 33003 filters before and after the pump, and have verified good fuel pressure (59psi on my OTC gauge). No excessive resistance between fuel pump B+ to battery and ground post to negative terminal.
 

cruisermatt

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Guessing you actually meant 33033 as a 33003 is a lawnmower filter... either way 33033 is only a 20 micron filter so not really rated for EFI. (Holley states a minimum of 10 micron rating for EFI fuel filters).

I would swap the injectors and see if the issue follows. I would bet you have a bad/clogged injector
 
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Definitely meant 33033 - I swear I'm not dyslexic. As for not meeting Holley's ratings, I just matched the part number that came in their kit - I'll double check and make sure I'm not mistaken.

Both injectors tested good, at 12.0ohms. Swapped the injectors, problem didn't move.
Took the fuel pump relay out to disable fuel and cranked it over, and there was no pulse at the injector connector...
Found out that the cheap connectors they use on the Snipers have 0 retention between the wire and terminal, so it just backed itself out and was making intermittent contact. Ran to the parts store to get an EV6 connector, spliced it in, and we're firing on all cylinders now.

S824 is the part number if anyone else ends up running into the same issue.
Appreciate the help.

Connector.jpg
 

cruisermatt

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Glad you were able to fix it.

As for the filters, double check the Holley instructions, the one you have is what they recommend for the pre-pump filter only.
 

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