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

  1. #1
    Join Date
    May 2019
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    Vancouver, BC, Canada
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    Default New engine starts, but runs terrible within a few seconds.

    I’m building a Factory Five 33 Hot Rod. The engine is a newly built Ford 347 with Sniper and HyperSpark distributor, coil & ignition box. Holley recommends that you get the Sniper running properly first before getting it to control the timing, but I didn’t have any regular ignition components laying around to do that with so I’m using the full kit from the get go.

    So the engine starts BUT after a few seconds it starts “popping” like crazy and I shut it down in the fear of damaging something. What do I mean by popping? Here’s a video so you can hear for yourself: https://www.youtube.com/watch?v=KiODs1YmitA

    I’ve read a few threads here and have eliminated a couple of things. All injectors are working and I’ve reverified engine TDC and distributor sync. I’ve also moved the Sniper and associated wires away from ignition stuff as much as possible, but let’s face it, it's an engine and they have to live in the same space – no parallel runs at least.

    Only thing Holley Tech suggested so far was to uncoil the handheld cable so it doesn’t pick up EMI. But that didn’t change a darn thing. At the moment, I’m suspecting the cable from the distributor to the Sniper and have some copper tape to try shielding it. This is quite frustrating and it seems that EMI is a huge weakness for the Sniper system. I'm also wondering if there is something the Sniper does (a change of state of some kind) a few seconds after start that might be a clue as to what's going on.

    Anyway, here is a datalog file that I took. Note it's not the same run as that shown in the video: https://www.dropbox.com/sh/tfc2003ui...Gkg5yJUha?dl=0. Would love to hear what you guys think and start to learn how to interpret these datalog files and what to look for, etc. Your help is much appreciated. Steve

  2. #2

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    You're pouring a ton of fuel into that engine and you're not in Closed Loop. First thing I'd do is figure out why it isn't in Closed Loop. Once you get it into Closed Loop the Sniper will have a fighting chance to lean itself out, but I'm afraid your tables are all setup way too rich for that engine. Did you build the tune or get it from someone? If you built the tune, maybe you checked the box for race cam?

  3. #3
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    Default

    Thanks for the reply. All I've done is follow the instructions, ran the Wizard, answered the questions. For the cam question, I've actually tried answering with both stock and street/strip with the same result. I haven't gone in and played with any tables or anything else, I have no idea how. I actually thought the AFR readings looked high, so it might actually be in a lean condition, but I'm just starting this journey of how to interpret this stuff. As for Closed Loop, doesn't it have to warm up first? I've not run it past 15 or 20 seconds at a time yet.
    Last edited by FF33ROD; 05-17-2019 at 05:38 PM.

  4. #4
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    Default

    You don't have a lot of vacuum, how big is your cam? Did you double check your firing order?

  5. #5
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    Yup, checked with Trick Flow on the order required, and quadruple checked the wiring. Also, confirmed distributor rotation is CCW. The cam isn't anything radical, hydraulic roller Stage 2 from Trick Flow 224°/236°: https://www.trickflow.com/parts/tfs-51403002. Heads are AFR Renegade 195cc. Compression is about 10.5:1. Why do you say there isn't much vacuum? I see about 66 kPa, when compared to 99 kPa before start is about 10 in Hg, no?
    Last edited by FF33ROD; 05-17-2019 at 06:33 PM.

  6. #6
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    Quote Originally Posted by FF33ROD View Post
    Why do you say there isn't much vacuum? I see about 66 kPa, when compared to 99 kPa before start is about 10 in Hg, no?
    Because a 224° duration @ .050" camshaft should idle a lot lower than 66 kPa MAP, which means the engine isn't idling well.

    As for Closed Loop, doesn't it have to warm up first?
    No! That's Learning. Closed Loop is active as soon as the WBO2 sensor completes the initial heating cycle. Check your Closed Loop/Learn parameters. "Enable Closed Loop" and "Base Fuel Learn Enabled" are the only parameters that need to be check marked.
    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. #7

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    Engine might have a vacuum leak.

  8. #8
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    Or he's in Open Loop with a poorly tuned Base Fuel Table. In fact, you already revealed the problem in the first sentence of post #2.
    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.

  9. #9
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    When your RPM comes down to about 1100, your MAP is at around 80 kPa. Look how spikey (is that even a word) your AFR trace is. My first thought is you have a misfire. Always save and post your Config File with any datalogs you post. That way we don't have to guess at your settings.

  10. #10
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    Originally Posted by Danny Cabral
    For further assistance, post your Config File and a short datalog of this occurrence for us to analyze.
    Also, review the datalog and inform us of exactly where in the datalog (time/seconds) the problem occurs.
    Datalog & Global Files can be linked to a document hosting website. I use Dropbox.com.
    Files can also be "zipped" (compressed zipped folder) & attached directly to a forum post ("Go Advanced" & "Attachments").
    Your Config File is in the "Documents", "Holley" folder, "Sniper" folder, "Config Files" folder (.hefi file).
    Your Datalogs are in the "Documents", "Holley" folder, "Sniper" folder, "Data Log" folder (.dl file).
    Someone will analyze/troubleshoot the problem & offer advice.
    https://www.youtube.com/watch?v=iqHOtDNiTNA (How To Record & Email A Datalog)
    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.

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