Holley Sniper

Green411 · #1 (**permalink**) 05-06-25, 10:10 AM

David, thanks the update.
I hope it works out for you as well as it has done for me. Mine isn't perfect, I occasionally get a stall when pulling away from stop during warm-up if I open the throttle quickly, but that's about it. I've left the programming completely alone ie it's all self-learnt. Maybe a few goes at more throttle from standstill while it warms up will nudge it to learn more in that particular TPS/MAP/CTS/oxygen sensor combination? Or maybe I've got an air or exhaust leak somewhere? Must admit I've never bothered with any data-logging with it.
Also my (Holley in-tank) fuel pump is noisy, even with a full tank. But at least I know it's working!

David C · #2 (**permalink**) 05-06-25, 03:31 PM

I think your pulling away issue has been fixed on the Mk 2. As both butterflies open together rather than one after the other with the carburettor I have to be quite gentle on take off or I get thrown back in my seat with quite a jolt. I haven't noticed huge pump noise but it may be due to all the other noises. There is quite a loud injector tick and I think noise from pulsing in the fuel filter mounted on the inner wing. More fettling and investigation required but it's a very promising start.
I will try to get up to one of the East Anglia meetings so that we can compare notes.

Green411 · #3 (**permalink**) 10-11-25, 02:57 PM

Update:
I mentioned that I occasionally got a pulling-away stall when the engine was cold. This developed into frequent cold stalling, including on the over-run when slowing for a stop, plus increasingly hard cold starting and occasionally dodgy hot starting.
I had a dig around on the Holley Sniper forum and it seems I'm not the only one with this type of problem. Suggestions were to check the Coolant Temperature Sensor reading vs the Manifold Air Temperature via the supplied HandHeld screen, as the OEM CTS have, in some cases, been shown to read high on a cold engine and low on a hot engine. On a cold engine the IAT read 55*f but the CTS read 71*f.....too much of a discrepancy. It's a common sensor type (Standard Motor Products TX3 or equivalent) and I had a spare which was known to be good. I swapped them over and all was good, with now only a 1*f difference.