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Flat Spot 4-6000Rpm

Pope

By Pope,
in Engines & Forced Induction

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Pope Apprentice

Pope

Posted
Posted

Hi,

I have recently fitted a Turboetech Boost controller to my car, and after winding the boost up to 9 PSI, the car now has a bad flatspot on acceleration between 4000 and 6000RPM, after 6000 it Revs past it, and seems to be fine. Between 4-6, its not like its missing, but just generally lacking power, like it can't breathe or something - but will rev past it in all gears.

Initally when I installed it, the car started missing badly, so I gapped the plugs to 0.8MM, and siliconed up the coils. The missing got a lot better, but I thought the flatspot was the same problem. I ordered and fitted spkitfire coils today, but the car still has the flatspot. It seems to mainly be when the car makes full boost - after 6000RPM it tapers off to about 8.5PSI and the fault seems to clear and car accelerates better - can feel the shove after 6000 - not sure if boost tapering is just a coincidence....

I have also tried an ECU reset, and have driven the car while watching readouts in OBD Scantech, nothing really stoodout as being massively wrong. There were no faults logged either. Also had quick check for boost leaks, none visible.

A couple of things I have seen on forums is checking ignition timing, or possible turbo breathing issues. I would have thought at this boost turbo would not be an issue. As for ignition timing - what should it be? Can probably check timing tomorrow arvo.

Anyone have any suggestions, or similar issues that have been resolved? Let me know if any more info is needed..I took a log using OBD Scantech, from about 2500RPM in third all the way to redline, as per zip file below Boost was max 9.2 PSI in this run

Thanks, Russel

.

Full list of mods/history

Car is 1993 series 1 R33 GTST

FMIC

Splitfire Coils

GFB StealthFX BOV

Cat-back 3in Exhaust

New plugs/fuel filter/all fluids

test run, third gear.zip

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https://www.sau.com.au/forums/topic/348144-flat-spot-4-6000rpm/
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Shazza24 Proficient

Shazza24

Posted
Posted (edited)

ECU, if standard may be the problem. TBH a good dyno print out could help, along with a good tuner to help diagnose the problem. May cost dollars but who cares, or wait for more people to comment! Come on mad082, I know your lurking some where!

EDIT: BOV may also be a problem, how was it before BOV?

Edited by Shazza24
Pope Apprentice

Pope

Posted
  • Author
Posted (edited)

Just watched the log file, had only seen live....it appears R&R is spot on, at about 4200RPM it drops timing back to 12 deg, at almost exactly 6000RPM it goes straight to 20deg, and works up to about 25 or so after that. So painful that its doing it at such low boost :(

Thanks for the help.

Edited by Pope

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