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Thread: New engine starts, but runs terrible within a few seconds.

  1. #11
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    May 2019
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    Vancouver, BC, Canada
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    Thanks for the help so far gents. I looked at the Config File and both Closed Loop & Learn are enabled. I've added the Config File to the Dropbox link above.

  2. #12

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    That engine sounds like it has a bad miss right from the get go. Are all exhaust tubes getting hot?

  3. #13

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    Probably the wrong firing order. I know you said you double checked it, but it could still be wrong. Pull the valve covers and double check it by watching the intake valve and the distributor rotor. Maybe someone sent you the wrong camshaft by mistake so you don't have the firing order that you think you do.

  4. #14

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    I’m going to suggest a valve adjustment or valvetrain interference issue. As soon as some heat gets generated, things head south. You may be hanging valves open. I'd double check your head/lifter/pushrod/rocker combination. You could have pushrods that are a little long for your combo or too much preload. This would also explain fluctuating AFR and low manifold pressure. Yes, it’s running fat, but it sounds to me like you’re getting combustion outside of the chamber.
    Last edited by Flatlander; 05-18-2019 at 06:06 PM.

  5. #15
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    May 2019
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    Today I took the valve covers off and redid the hydraulic lifter adjustment. I also pulled the spark plugs and replaced the ignition wires. Interesting find on the spark plugs - cylinders 2, 3, 5 & 8 are all running super rich. This corresponds to the lower plane of the Edelbrock Performer RPM Air-Gap dual-plane intake manifold. I regapped the plugs and put it all back together. The results wasn't much different than previously. Lots of popping after a few seconds. Here's a new datalog (Config File is in the drop box link at the beginning of this thread.) Sniper_0006.zip
    Click image for larger version. 

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    Can't help but think that at least part of the problem is the HyperSpark ignition, noise on the connection from the distributor to the Sniper? What about these crazy abrupt transitions from 15° BTDC & 35°? Also, why does the Sniper actually back off to less than 15°?
    Last edited by FF33ROD; 05-19-2019 at 11:39 PM.

  6. #16
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    Dec 2009
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    Connecticut
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    Quote Originally Posted by FF33ROD View Post
    What about these crazy abrupt transitions from 15° BTDC & 35°? Also, why does the Sniper actually back off to less than 15°?
    Originally Posted by Danny Cabral
    The Target Air/Fuel Ratio Table & Base Fuel/Timing Table (and MAP kPa & RPM axes/scales) should be configured using the Sniper EFI software:
    In the Sniper EFI software (LINK), Target Air/Fuel Ratio Table (Fuel ICF) & Base Timing Table (Spark ICF), select "2D Table" Type (not "Simple").
    The Target Air/Fuel Ratio Table & Base Timing Table can then be properly configured & tuned for any engine.
    https://www.holley.com/support/resou...Fuel_Injection (Sniper EFI Software & Holley 558-443 CAN/USB Dongle)
    https://forums.holley.com/showthread...679#post100679 (Sniper EFI Optional Comm/Data Cable Accessories)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2700 RPM converter, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  7. #17
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    May 2019
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    Vancouver, BC, Canada
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    Thanks Danny. Yes, I'm aware that the software can be used to tune all sorts of things, but I would have no clue as to where to start. This system is pretty much sold as plug & play; launch the Wizard and the rest pretty much sorts itself out as it runs (Learning). Thought the software was only needed if you wanted to "fine tune", as in get the last bit of performance out of the engine. Any suggestions as to where to go from here? It's not valves, it's not firing order, not ignition wires.

  8. #18
    Join Date
    Nov 2014
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    Ont. Canada
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    Did you look down the TB when it is running to verify all injectors are firing? Did you verify your commanded timing from the ECU matches what you're seeing at the crank with a timing light?

  9. #19
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    Quote Originally Posted by FF33ROD View Post
    Thanks Danny. Yes, I'm aware that the software can be used to tune all sorts of things, but I would have no clue as to where to start.
    I simply answered the question in post #16. If you don't know to use the 2D Table, you'll need someone to help you.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2700 RPM converter, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  10. #20

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    Well those plugs are a big clue. Maybe only one side of the Sniper is working?

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