HiTech Posted March 27, 2010 Report Share Posted March 27, 2010 flipped the switch on today to fire up one our cars ..with out hitting the start button ..the distrbutor starting humming ....never heard that before ... ..i got to looking things over .checked and added a new motor to chassis ground .didnt stop it .i pulled the coil wire .hit the toggle and that coil was fireing like mad ..like it would holding the coil or plug wire to something if it was running .. .. .this is all going on with the motor off ..when it starts .you cant hear it ofcourse ...so flabbergasted .i took the cap off .and it was burning up and started to melt ..checked the rotor .no problem . there .. cleaned the dist .and added another cap .thought that fixed it .after starting the motor up and turning it off .i hit the switch again and that hum came back .. something is not right ..has anyone ever seen this .why would it keep firing when your not trying to start it ..... lucky for us .we had a stock setup .ready just in case . with the car alredy wired for the stock .and thats the way i went .stock .the msd box has a chip .. would it be posible something went haywire in the box ..this box ran one night after the big big hit the car took last year ///wonder if that hurt it ..btw ..i changed to another msd dist .and it did the same thing .. Link to comment Share on other sites More sharing options...
jwmbishop Posted March 27, 2010 Report Share Posted March 27, 2010 Sounds like a capacitor is not holding up its voltage and creating a spark signal based on voltage fluctuation caused by the capacitor itself - that would mean the MSD box is likely bad as these are the non serviceable part of the controller. Just a WAG tho. Measure voltage at the 12V supply wire(s). If 12.3 or better going in, replace the box. If under (assuming battery is above) you have a short somewhere, or wiring that has degraded and just wont let them lil electrons run. Sometimes the switch itself can reduce voltage to a point below what the box can use. I use a switch to fire a relay - relay to fire the box - that way if voltage drops below 12.3 the relay lets go and there is NO ignition. Must run an alt in this method! Running the MSD6 below 12.3 volts will work for a period of time. However it does not like this and after that period does all sorts of goofy stuff. Generally speaking I saw a 2-3 volt drop from beginning of heat races to end of main when not running an alt (even putting a charger on between lap sessions). Fully charged at 14.2 - do the math! Especially bad when you spin and have to hit the starter - you can drop to 9 easily - at that voltage it tries to fire very erratic and continously (kinda like you are describing)! And being a fresh season if your battery is old it may SHOW 12.3 but drop to 12.1 as soon as the ign is turned on. (older battery equals shorter cycle between charges) Also the MSD likes amperage. If your supply circuit can not provide a full 30 amps - you will see issues. Link to comment Share on other sites More sharing options...
HiTech Posted March 27, 2010 Author Report Share Posted March 27, 2010 ill check those ..he had problems with a toggle switch last year .another maybe bad ..the battery is brand new .ill check the load next week .. we dont run alt ..we keep the batterys on a trickle all week long ..1.amp ...the box is probaly 4 to 5 years old .. the wreck the car was in last year .was full throtle right front to broadside at cc last year ..it bent stuff on the other side of the car . that how much impact it was ..hurt the driver ....so my thought maybe the box took it to hard ...the battery was wasted just from the impact. may have shorted aswell . Link to comment Share on other sites More sharing options...
jwmbishop Posted March 27, 2010 Report Share Posted March 27, 2010 I don't remember the details - but do recall something about the msd wire colors not matching the distrib colors - verify your wiring! According to MSD the unit should still fire at 9 volts. From MSD T\S guide (modified to solve for your problem): If triggering the ignition with the White wire (Points\condensor): 1. Make sure the ignition switch is in the "Off" position. 2. Remove the coil wire from the distributor cap and set the terminal approximately 1/2" from ground. 3. Disconnect the MSD White wire from the distributor's points or ignition amplifier. 4. Turn the ignition to the On position. Do not crank the engine. 5. Tap the White wire to ground several times. Each time you pull the wire from ground, a spark should jump from the coil wire to ground. If spark is present only at ground break, the ignition box is working and the condensor is the likely culprit. If triggering with the Magnetic Pickup (HEI with Module removed, magnetic Distributor or Crank Trigger): 1. Make sure the ignition switch is in the "Off" position. 2. Remove the coil wire from the distributor cap and set the terminal approximately 1/2" from ground. 3. Disconnect the MSD magnetic pickup wires (green and Purple) from the distributor. 4. Turn the ignition to the On position. Do not crank the engine. 5. With a small jumper wire, short the MSD's Green and Violet magnetic pickup wires together. Each time you break this short, a spark should jump from the coil wire to ground. If spark is present ONLY then, the ignition box is working properly and the distributor (or the crank trigger sensor) is the likely culprit. If you bent stuff on the side opposite the hit I guarantee the car saw at least 4 g's in force. Enough to wipe out the box for sure! I would suggest mounting any replacement on a thick rubber pad so it won't absorb any unwanted g forces! Link to comment Share on other sites More sharing options...
HiTech Posted March 28, 2010 Author Report Share Posted March 28, 2010 i checked all wireing .we didnt change anything from last year ..except the battery ....the car has only one race on it last year after the wreck .. a few good poeple worked thier bones off pulling the fame back into place .and all the suspention that had to replaced . his dad drove it .just for show .and to thank everyone who helped ..a statement kinda thing .you might say ..looked ok and was trying to set up for the lead when the motor decided it wanted to exspand into a 5 cylinder from four ..lol ..a couple of thousand down the drain .... figured it may have had something to do with the wreck .seeing the motorwas stoped purty fast from 7500 or so to 0..just like that ... re-ring the motor the week of the wreck .so i know it was good till then .... as for g force ..more like 8 or more . knocked the wind out of him .put em in lala land for alittle .his right hand flew off the wheel .and shattered the mirror on the other side of the car ..which in turned aloud him to recieve so dammage to his hand that required attention at the hospital ...at the time he was in the running for the championship .not far behind with a couple of weeks left ..we will never know how that would have come out ..new year new paint .and this showed up ..lol Link to comment Share on other sites More sharing options...
trlrider Posted March 28, 2010 Report Share Posted March 28, 2010 ... either a bad trigger in the distributor or a shorted coil. more than likely the trigger in the distributor, which would cause the coil to fire all the time! Had this happen years ago, actually on a street vehicle with a MSD HEI distributor! flipped the switch on today to fire up one our cars ..with out hitting the start button ..the distrbutor starting humming ....never heard that before ... ..i got to looking things over .checked and added a new motor to chassis ground .didnt stop it .i pulled the coil wire .hit the toggle and that coil was fireing like mad ..like it would holding the coil or plug wire to something if it was running .. .. .this is all going on with the motor off ..when it starts .you cant hear it ofcourse ...so flabbergasted .i took the cap off .and it was burning up and started to melt ..checked the rotor .no problem . there .. cleaned the dist .and added another cap .thought that fixed it .after starting the motor up and turning it off .i hit the switch again and that hum came back .. something is not right ..has anyone ever seen this .why would it keep firing when your not trying to start it ..... lucky for us .we had a stock setup .ready just in case . with the car alredy wired for the stock .and thats the way i went .stock .the msd box has a chip .. would it be posible something went haywire in the box ..this box ran one night after the big big hit the car took last year ///wonder if that hurt it ..btw ..i changed to another msd dist .and it did the same thing .. Link to comment Share on other sites More sharing options...
HiTech Posted March 28, 2010 Author Report Share Posted March 28, 2010 ... either a bad trigger in the distributor or a shorted coil. more than likely the trigger in the distributor, which would cause the coil to fire all the time! Had this happen years ago, actually on a street vehicle with a MSD HEI distributor! thanks i thought it was one of those at first ...i tried a new coil .that didnt help .... i installed another dist . worked for a second thought that fixed it ..but went right back to doing it ..but i didnt try both at the same time ...something i never seen before in any typ of system ...sounds like a floresent light hum .... Link to comment Share on other sites More sharing options...
raeasler Posted May 9, 2010 Report Share Posted May 9, 2010 You try running a ballast resistor in it like the old Dodges used to? I had one on my 4X4 that was doing the same thing. The resistor did away with the problem with minimal voltage drop. The eye is not supposed to have full voltage applied to it to work. MSD website states that. Obviously system dependent. Are you running the MSD distributor electric "eye". Bought it for a 74 Dodge Dart with a 318. Link to comment Share on other sites More sharing options...
KISS_Racing Posted May 11, 2010 Report Share Posted May 11, 2010 what did ever happen with this? Mark Link to comment Share on other sites More sharing options...
HiTech Posted May 11, 2010 Author Report Share Posted May 11, 2010 what did ever happen with this? Mark we went with a stock set up .so have not checked anything sense.... i think it was the box .the distributor is running in another motor .. Link to comment Share on other sites More sharing options...
Danielsen Motorsports Posted May 24, 2010 Report Share Posted May 24, 2010 Its miswired. I know you think I am full of balony but we had the exact same thing. I got so ticked off I took my car to Chris Swenson and he found two wires that needed to be swapped. Per directions that I had in hand it was wired correctly. But without a HEI module inside the distributor the directions were not correct. Even having it miswired it did not damage anything. Once we swapped the wires it fired off like no big deal. This was like 4 years ago so I cant remember which 2 wires they were sorry about that. Hope this helps. Link to comment Share on other sites More sharing options...
HiTech Posted May 24, 2010 Author Report Share Posted May 24, 2010 Its miswired. I know you think I am full of balony but we had the exact same thing. I got so ticked off I took my car to Chris Swenson and he found two wires that needed to be swapped. Per directions that I had in hand it was wired correctly. But without a HEI module inside the distributor the directions were not correct. Even having it miswired it did not damage anything. Once we swapped the wires it fired off like no big deal. This was like 4 years ago so I cant remember which 2 wires they were sorry about that. Hope this helps. i prefer salami ...lol .ill look into that when we get a new block built ..but as far as i know ..we didnt change anything from the last race season ... Link to comment Share on other sites More sharing options...
Danielsen Motorsports Posted May 25, 2010 Report Share Posted May 25, 2010 of course its certainly possible more then my experience might could cause this noise your hearing, good luck!!! Link to comment Share on other sites More sharing options...
KISS_Racing Posted May 25, 2010 Report Share Posted May 25, 2010 flip green & purple... Link to comment Share on other sites More sharing options...
usra43 Posted May 25, 2010 Report Share Posted May 25, 2010 My tach. and shift light is what fried my msd box at one time. Crazy huh? Both went bad and took out the msd box with it. Link to comment Share on other sites More sharing options...
KISS_Racing Posted May 25, 2010 Report Share Posted May 25, 2010 Put a volt meter on it while it is running. Just remembered we had an alternator going out that caused issue with low voltage on one as well. Link to comment Share on other sites More sharing options...
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