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Thread: Boost Spikes

  1. #1

    Default Boost Spikes

    Just recently I started getting boost spikes. I’ve checked my wastegate diaphragm & hoses, all OK. Also replaced the dome pressure sensor. I’ve noticed on my datalogs that the vent & fill solenoids as well as dome pressure tend to vary quite a bit rather than be stable. I didn’t want to mess with PIDs because it ran great before, just one day it decided to boost to 25 psi where I have my ignition cut for it. Any ideas where to check would be great.

  2. #2

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    You need to tune the PIDs. The dome pressure should follow "Target Boost" very well. Bring them both up on the datalog and scale them the same.

    Keep in mind if you tune them with the car off you need to uncheck "TPS Modulation". Also when you are done, take each value and reduce them by 25%. They will behave differently at the track.

  3. #3

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    What solenoids are you using, and what are your PID values?

  4. #4

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    @allan5oh: OK I'll give it a try. But is it common to have to mess with them once they've been set?

  5. #5

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    Holley solenoids, I’ll have to double check, but I believe it was P-20, I-10, D-0

  6. #6

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    @nvmyss: Not usually no. But anything can affect them. Regulator pressure, voltage, etc.

  7. #7
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    Default

    Quote Originally Posted by nvmyss View Post
    Holley Boost Solenoids, I’ll have to double check, but I believe it was P-20, I-10, D-0
    Read pages 1 & 2: https://documents.holley.com/techlib...reoverview.pdf (Holley EFI - Specific V5 Build 110 Updates)
    https://www.youtube.com/watch?v=HWj3...7&index=2&t=0s (Holley EFI - Boost Builder How To)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS T/W 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 12:1 C/R, TFS R-Series FTI ported intake, BBK 80mm T/B, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 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, -6AN fuel system plumbing, Walbro 255 LPH pump, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, FPP aluminum driveshaft, FPP 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 M/T Street Comp tires.

  8. #8

    Default

    Quote Originally Posted by lazaris View Post
    What solenoids are you using, and what are your PID values?
    Quote Originally Posted by Danny Cabral View Post
    Read pages 1 & 2: https://documents.holley.com/techlib...reoverview.pdf (Holley EFI - Specific V5 Build 110 Updates)
    Sorry, I was wrong:
    P Term = 15
    I Term = 20
    D Term = 0

  9. #9

    Default

    @nvmyss: Are they the Holley high flow or the dual MAC valves?

    I'd try what Allan said about reducing the values. They absolutely react different at the track. I'd get one run with barely any erratic spikes then some spiking on another. Let us know what happens.

  10. #10

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    They're the (MAC) Holley rebrands, not their newest versions. Just got back from a trip, so I'll work on it tonight and leave some feedback.

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