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Thread: Cuts Out When Adding Dome Pressure

  1. #1

    Default Cuts Out When Adding Dome Pressure

    Something new has started to happen with my new build, and I can not figure what it is. I believe I have it narrowed down to when I add pressure on the dome for more boost, the engine cuts out when it's reaching peak boost. I disabled/ignore the Safeties, thinking that it may be spiking and causing the ignition to cut out. 8 psi spring and I'm trying to add 6 psi to the spring/dome for 14 psi of boost. When I add even just 1 psi to the dome, it cuts out under high load near max boost. BUT when I'm running just on the spring, doesn't do it. It's a very significant cut out, almost certain it's ignition. Could it be the Target Rate Limiter (currently set to 100 psi/sec)? I have a datalog if that would help anyone. Any feedback or ideas are appreciated. Pulling my hair out on this.

  2. #2
    Join Date
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    May be as simple as you have too wide of a plug gap.
    Forced induction, we start around a gap of .020".
    When you start making 20 psi, we reduce it down to .018".
    At 30 psi, we put the plug gap at .014"~.015".
    You can post your datalog using Dropbox or File Dropper.
    -Scott
    Don't forget to check out progress on my Race Car:
    Project Blasphemy - 8.07 @ 171
    Low 8 Second Street Car

  3. #3

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    That make good sense, now that I think about it. I changed to a cooler BR7EF plug. I was told to use the factory .030" gap under 15 psi of boost. Datalog in Dropbox:
    https://dl.dropboxusercontent.com/u/...7/Cut%20Out.dl

  4. #4
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    Quote Originally Posted by gsxr04kid View Post
    I was told to use the factory .030" gap under 15 psi of boost.
    Well, there's your problem (it's common). Also, ensure your ignition system is powerful enough for forced induction.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, 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.

  5. #5
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    Quote Originally Posted by gsxr04kid View Post
    That make good sense, now that I think about it. I changed to a cooler BR7EF plug. I was told to use the factory .030" gap under 15 psi of boost.
    We don't even use a .030" gap on a naturally aspirated engine when racing. LOL. Gap them tight. You will be good to go. I'm on a BR7EFS, at 20 psi, gapped at .018"...no issues. 11.5:1 compression, C16. It's gonna be 30 psi here by the end of the year, once I have some time off. (It's warm where I live, we race all year round.)
    -Scott
    Don't forget to check out progress on my Race Car:
    Project Blasphemy - 8.07 @ 171
    Low 8 Second Street Car

  6. #6

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    I was really hoping it something that simple. Unfortunately still doing it, set the plugs to .020". To better explain the situation; from a slow roll if I lay into it, pulls hard making good power & building boost, and then it just falls on it's face like something has deliberately commanded it to. Doesn't seem to be RPM specific, but it does it near the 5,000 RPM range. If you try to get back into it, it doesn't want to accelerate until you get off the throttle completely, like there is a TPS minimum that must be reached, which makes me think it is in the ECU. It didn't do this before on the same setup. So it leads me to believe that either I made a change to the tune accidentally that is causing this, or I have something electronically malfunctioning/failing. Datalog from the incident: https://dl.dropboxusercontent.com/u/...7/Cut%20Out.dl

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