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6A causing loss of RPM?

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  • 6A causing loss of RPM?

    I have a Digital 6A CDI box on a big block Chevy with Terminator TBI. The EFI is controlling timing of a GM small cap HEI distributor.

    If I rev the engine up to a random RPM and hold it there, it will drop back to idle. The RPM is random and it can take 5-30 seconds for it to happen.

    I had the CDI box checked by MSD and it was tested as good. I've replaced the cap, MSD 8226 coil, rotor, plug wires & plugs. I'm using a Performance Distributors computer controlled HEI distributor. The only thing not replaced is the module in the distributor.

    Power & ground are connected to battery. Engine and chassis are grounded. I’m using the MSD harness 8876 to connect the CDI box to the coil and distributor.

    If I disconnect the CDI box the engine runs fine, revs up & doesn't cut out. One other thing is, with key-on/engine-off, the LED light is a solid red it does not blink five times as said in the instructions. To me it sounds like the CDI box is bad, but it tested good. Any help would be appreciated.
    Last edited by TMat; 05-15-2023, 10:42 PM.

  • #2
    I think you'll have to replace the Digital 6A CDI box.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385"/6.3L SBF, Dart SHP 8.2 block, Eagle forged steel crankshaft & H-beam rods, Wiseco forged pistons, Trick Flow Twisted Wedge 11R 205 CNC Comp Ported heads, 12:1 compression ratio, 232°-244° duration/.623" lift/114° LSA H/R camshaft, TFS R-Series FTI Comp Ported intake, BBK 80mm throttle body, Holley Dominator MPFI & DIS, Holley 36-1 crank trigger, MSD 1x cam sync, PA PMGR starter, PA 200A 3G alternator, Optima 34/78 Red battery, 100HP progressive dry direct-port NOS, R134a A/C, Spal Dual 12" HP 3168 CFM fans, Frostbite 3-core aluminum radiator, Pypes SS dual 2.5" exhaust, SS off-road X-pipe, SS shorty headers, Earl's -6AN fuel system plumbing, Walbro 255 LPH in-tank pump & Pro-M -6AN hanger, S&W subframe connectors, BMR upper & lower torque box reinforcements, LenTech Strip Terminator wide-ratio Ford AOD, 10" 3000 RPM C6 billet converter, B&M Hammer shifter, Stifflers transmission crossmember & driveshaft safety loop, 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.


    • #3
      Replace it even though MSD tested it and the result was all OK?