I put a Digital 6 plus box in my car and it runs great but......it as a miss in it almost like the power of to the box the then it run fine again I have been on the phone with MSD tech and he can't tell me what it is I tried two boxes now mounted it in differnt spots wired it all diffrent ways and it still does it. it is driving me crazy!!!!!!!I wired up the 6AL box and it is fine......any idea????anyone else have one of these???The tect guy told me to change my plugs but that does make any sense to me....there not old and the coil and wires only two years old.....
I have one, it hasn't missed a beat for me since it fried the Accel coil I hooked it up to first. I now run the MSD 8200 coil, one of the few still made in USA. How are you triggering it? Have you cut the magnetic compensation (green loop)? Are you sure the cylinder select is in the right position? Do you have the blue and pink wires taped off or are you using the 2ndary rev limiter and high speed retard. Where is the miss? At idle? or Higher RPM? Kinda hard to understand what the problem is.
This is driving me crazy it does it at any RPM it sounds like the engine shuts off for a spit second msd tech say it is noise from something but i have run the car with the box outside the car on a bench wired to the battery with not one thing hook up unwired the alt. took the belt off it it does the same thing wired the key on power to a switch as not got better or worse if i put the 6al box in it is fine....it doesn't do the same time it could run for 5 minute fine and do it or it will do it 5 times it row and it kills the car ...and this is the second box too
What other electronics do you have in the car? What plug wires are you using? Are you saying this is the 2nd Digital6 box you are trying? Obviously, something is interfering with the microprocessor. Can you try another set of plug wires? Try rerouting the pick up wires, see if that helps. My Digital 6 has been trouble free for years.
MY next try was going to be plugs wires but there tayor 8mm wires it is the 2 box the pick up wire I routed them ten differnt ways even out the front of the car I had every electronic thing that is in the car shut off or disconnected it is either the coil, wires or distributor that is a msd pro-billeto No: o No: o No: o No: o No: o No:
The digital box can't be run with solid cores wires since it causes interference. I don't know off hand if those Taylors are solid or not. It doesn't sound like your problem though. The pickup wires off the distributor that you plug your MSD box into MAY be wrong. I have heard some MSD distributors have been wired backwards before. It would still run but not run good. What would happen is the coil would fire the rotor in between the terminals in the cap instead of directly at the tower. (This would give you your random misfire).If you have the timing set, hand turn the motor to #1 and line up the timing mark to where you have the timing at. Now pull the cap off the distributor. If the rotor is inbetween the towers on the cap instead of directly where the #1 wire is, you have found your problem. It is either wired backwards coming out of the distributor OR the rotor phasing is way off.
Are you using the same power and ground supply leads to energize both the digital6+ and the 6a ?? are the connection EXACTLY the same ?? if not, what is different ?? Im thinking a ground problem - something intermittant - like the tech said, something creating "noise" (you know hw meant electical "noise" ??) or perhaps something changing the impedance of the ground but not totally creating an open circuit. You are are the right track - Error analysis of multiple variables consists of eliminating unknowns for good known's - one at a time. Good "known's" could come from another car known to work properly. Work your way through replacing ONLY ONE item at a time ... even JUST ONE spark plug wire at a time. You could just replace all 8 and fix the problem but then you will not know which one was the culprit Personally - I'd do the coil first (easiest) , then the Distrib ... and then start swapping wires also - back to the ground ... how is the engine grounded to the chasis ?? typical ground strap from back of head to firewall ?? How do BOTH of those connection as well as the strap look ?? Also Also .... can you make this happen while not driving, i.e.with the hood up while looking at the box ?? If so, does the LED lite on the box flicker when it happens ??
it is wired right to the battery I tied it wire to a diffrent battery and the same thing over over again the distributors is right i chack that out ...also right now the msd 6al box is in the car and it is fine...I don't have time to play with it anymore I have to get ready to race next weekend.....
I'm surprised Bobb didn't say anything because he went thru the exact same thing with his digital box when he made the change(said the same thing too....)
If you look at the wires coming off the pickup, you'll see one is black with an orange tracer, and one is black with a violet tracer. The pickup harness is green and violet. All you have to remember is not to connect violet to violet. The black/violet pickup wire should go to the green harness wire and the black/orange pickup wire should go to the violet harness wire. I remember guys reversing polarity when using the Stinger pickup to fire an MSD. Wrong polarity would make the engine run very advanced timing.
Yup went though that with MSD tech also had I guy at track that did that car ran bad till I looked at mine and seen that they don't match up I don't know what is going on here!!!!
The polarity has nothing to do with the timing per say. If you have it setup backwards and switch the wires, it changes what the MSD sees as a signal and THAT changes when the MSD delivers spark. You have to understand what the MSD reads to understand. The MSD read/sees the "peaks" of the signal when it crosses the pickup points. When the polarity/wires is reversed the peaks are going down instead of up so the signal is backwards. Therefor the MSD reads the spot inbetween the pickup as the peaks. You can get a car running, timing set, and set it up like this but it will have problems such as a miss or runs bad at rpm. When you swap the wires back it will run like crap until you reset the timing since it will be seeing the signal in a different spot. Most of the time when it is wrong and you switch the wires, the timing is retarded and runs like crap. It doesn't "retard" the timing, it changes the timing. The MSD is just picking up its signal in a different spot so the timing will be different. BUT the easy way to check this should be with rotor phasing. You should be able to pull the cap with the #1 at 10-20 advanced before TDC on the firing order and the #1 on the cap and rotor should be lined up with the tab on the rotor. If it is off, the rotor SHOULD be in between two of the towers on the cap instead of pointing at #1. Either way, if you swap the polarity, you will have to reset the timing. IF IT IS ALL WIRED RIGHT, then check your rotor phasing. The spark could be jumping to the next closest tower in the cap if it is off since there is less resistance on a cylinder that is not firing.
Rick, I understand what you are saying, but I remember reading about this issue back on the old GSCA BB. I printed out some of the posts I found interesting, so I went to look. I found a page where Charlie Evans and Bruce Wilson were discussing this.
Larry what plugs are you using I run NGK which are non-resistor plugs the msd tech said that is fine but I talk to someone else had installed a crane digital box and it did the same thing mine is doing they changed the plugs and it was fine????
I have TA Aluminum heads so I run the NGK FR-5's which are flat seat gasket plugs. For Iron heads, the NGK UR-5 is the same plug with a tapered seat. Both plugs have a projected nose. I've had good luck with these plugs. You may not be able to find them in the parts stores. I get them online at www.rockauto.com
