Results 1 to 7 of 7

Thread: Cannot control spark with my MSD distributor and Digital 6+ ignition

  1. #1
    mrvedit Guest

    Default Cannot control spark with my MSD distributor and Digital 6+ ignition

    I have just installed my 950 and wired it according to Figure 83 (Page 108) with my MSD 85551 connected over a shielded cable to the Green/Violet on the 950. I have locked/disabled the mechanical advance in the distributor. The 950's white wire goes to the white wire on my MSD ignition.
    Car starts and idles fine. However my ignition advance is static - the C950 clearly is not controlling it. I have forced values like "1" and "30" into blocks of the Spark Map, but my timing light show the exact same timing (now at 24°) no matter what the RPM or values in the spark map.

    Everything is very well grounded; I'm an electronics guy and even have a scope hooked up to verify that everything looks good. Is this supposed to work? Or does it really only work with a true crank trigger? Thanks, Ted.

  2. #2
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,962

    Default

    In the Modifiers screen (under Fuel), are all your "Additional Timing vs. Coolant Temperature" values set to -32°?
    If so, change them all to zero.
    Last edited by Danny Cabral; 08-29-2010 at 05:41 PM.
    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.

  3. #3
    mrvedit Guest

    Default

    Thank you for your extremely fast reply! Very much appreciated and I will post on other forums that Holley even provides support on Sundays!

    Every value on that screen is 0.0 or 0. By your reply I assume that it should work. Since the 950 is between the distributor and the ignition box it should have the ability to change the timing; I am absolutely sure it is wired that way. Under Engine Parameters -> Ignition, I have "Magnetic Pickup" selected. I'm running a 383 SBC.

    Should I try reading a complete fuel/spark map again, e.g. the SBC383? I have only changed a few idle related values so far.
    Or do you have another suggestion? Is there an on/off setting for spark control? Thanks, Ted.

  4. #4
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,962

    Default

    Quote Originally Posted by mrvedit View Post
    Under Engine Parameters -> Ignition, I have "Magnetic Pickup" selected.
    What is your Ignition Reference set to? Should be 60° (at least 10° more than maximum amount of timing used), then synchronize timing at idle, by turning the distributor and locking it down (don't touch it again). Afterwards, adjust the Propagation Delay to synchronize the timing at higher RPM - 3500 RPM. You'll need your timing light for both settings.


    Excerpt from C950 EFI manual:
    NOTE: It is not advisable to use a magnetic pickup distributor to directly feed the magnetic trigger input of the C950. If the
    magnetic pickup distributor is connected to the C950 via the inductive pickup trigger wires, the pickup/rotor/cap phasing
    must be corrected. This operation may require a phaseable cap or rotor or possibly machining to the distributor and is
    therefore beyond the scope of most users. Even with the phasing corrected, the electrical noise inside the cap may be
    strong enough to cause tuning problems. It is advised to use a crank trigger system or a computer-controlled
    distributor.
    Last edited by Danny Cabral; 08-30-2010 at 02:47 AM.
    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
    mrvedit Guest

    Default

    My Ignition Reference is set to 10; I will try what you suggest. I understand the pickup/rotor/cap phasing issue - I have read A LOT on it since my last post. It seems that a crank trigger only partly solves it - you still have a rotor/cap phasing issue, but at least that is now independent of the reluctor/pickup. Am I correct that minimizing the minimum/maximum advance (e.g. min 30°, max 44°) also minimizes the phasing problems? I don't yet understand how the "Ignition Reference" is related to phasing. (However there is still the issue of start retard.)

    Could you please document whether the 950 provides advance by anticipating the next ignition pulse or delaying the existing one. Since you imply that the distributor should be set to about 60° of advance, it sounds like the 950 delays the existing one by varying amounts to provide the desired advance. Please confirm.

    I have not yet learned how a "computer controlled distributor" solves the phasing problems, but if indeed it fully solves them, then I'm inclined to go with that option since a crank trigger still leaves the rotor/cap phasing issue. While the MSD 85501 has "locked out" timing, I suspect that is not what you mean by a computer controlled distributor; therefore please suggest one or more. Thank you, Ted.

    Update - I just called MSD and they said they get 50 calls a day on this phasing problem and in most cases the adjustable 84211 takes care of the problem. I will start with that. Thanks, Ted.

  6. #6
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,962

    Default

    Quote Originally Posted by mrvedit View Post
    Update - I just called MSD and they said they get 50 calls a day on this phasing problem and in most cases the adjustable 84211 takes care of the problem. I will start with that.
    I don't think that's what you need at all. Your problem is software related; not hardware related. I can assure you, MSD does not get 50 calls a day on EFI applications. If you had the Ignition Reference set to 10, that's why it wasn't advancing. 60° of Ignition Reference allows up to 50° of available timing.

    Read my last post, everything you need to do is detailed there. You also have the option of using a GM small-cap, computer controlled distributor (dual connector) found in cars from 1987-1993 and trucks from 1987-1995; which is what most C950 owners use.
    Last edited by Danny Cabral; 08-30-2010 at 02:02 PM.
    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.

  7. #7
    mrvedit Guest

    Default

    Thanks for the quick replies. We weren't quite on the same page. I assumed that setting the "Ignition Reference" to e.g. 60° would work and it did! Thank you for figuring that out. I had changed it to 10 when I first tested the C950 without controlling the spark. My questions were related to the best way to solve the rotor/cap phasing problem, although it seems to be working OK. However, I'm still concerned that the rotor/cap phasing might cause misfire in some situations; therefore I will order the MSD 84211 adjustable rotor as MSD tech support suggested. Ted.

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
About us
Holley has been the undisputed leader in fuel systems for over 100 years. Holley carburetors have powered every NASCAR® Sprint® Cup team and nearly every NHRA® Pro–Stock champion for four decades. Now, Holley EFI is dominating the performance world as well as our products for GM's LS engine. Holley's products also include performance fuel pumps, intake manifolds & engine dress–up products for street performance, race and marine applications. As a single solution, or partnered with products from other Holley companies - Hooker Headers, Flowtech Headers, NOS Nitrous, Weiand, Earl's Performance Plumbing, or Diablosport - Holley products can give you the edge you need over the competition.
Join us