Hey Guys and Gals. The PO of my '88GT installed an MSD Ignition system and the radio buzzes like crazy when running. It is like having an audible Tach! Maybe that is good. What is the filter for this I need to replace? Thanks Everyone.
I believe that the MSD spark plug wires are solid, which means they were meant for racing, and will always mess up your radio. If you decide to go back to a stock setup, be sure to replace ALL the MSD components.
MSD box etc on most cars is junk and can be your noise problem.
But Factory and aftermarket radios goes bad/dead from old age. Just 1 example: GM has a big cap in the radios near the main plug that goes bad and does nothing. Worse if you use AM because any electric noise in the car come thru. IOW Even w/ standard "anti noise" wires and plugs you get a lot of ignition and alt noise in many old radios.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
Thank you for the responses guys! I will check a few things. I thought maybe that there was a specific ignition noise filter that was left out or something. My original '88 is all stock and 30 years later the radio is noise free. I never dealt with the MSD system before and I figured it did a whole lotta nothin'....Fred W
Originally posted by 88Fingers: I never dealt with the MSD system before and I figured it did a whole lotta nothin'.
It does quite a bit. It more than doubles the voltage of the secondary ignition (ignition coil, dist. cap, spark plug wires and spark plugs)....which may (or may not) be a benefit on the race track, but does not do a thing for normal driving. In a Fiero, it has been blamed for failure of the Ignition Control Module, and if you keep the MSD coil and use stock components otherwise, it will cook them....
Hey Gall757, thank you for that insight. I don't know how long the PO had it in in there. He also told me that a whole new distributor was just put in last year. The big red box is mounted in the trunk and everything else looks stock including the coil. The wires plugging into the coil feel crispy! There is an open wire and connector hanging out of the left side of the red box not connected to anything either. Any ideas? Should I remove this whole system or could it be useful at some point? Thank you.
hmmmm. I like driving in the summer listening to the radio. If you do autocross the car maybe you want to keep the MSD, but components may not last so long as evidenced by the PO replacing the distributor. It's your call! Sorry I don't know more about various wires.
Thanks for the responses Gall757, I may just remove the MSD and try to get back to the original setup. My original '88 is all factory stock and it always fires up and runs great at all revs! I think it is a bit of overkill and I need reliability for this car. No Autocross but major endurance event. Rodney Dickman holds my mortgage now anyway so here we go again. Hello? Rodney?......
Normal stock spark wires are resistive.. meaning that once the arc over begins, the wire prevents super high currents from flowing. Radio noise is a result of high EMI being generated in the ignition. EMI is a result of fast changing currents, or high DI/DT. Racing wires are non resistive and allow higher currents, and worse in this case, fast changing currents. I have studied the MSD.. it switches the 12V up to about 600V. And when it goes to spark, it dumps the voltage on the coil RIGHT NOW. So that is a double whammy.. the higher voltage is meant to overcome the delay in current rise that inductance introduces.. the higher the voltage, the faster the DI/DT. And part of the reason for something like CDI is that you can spark a lot faster for high reving 8 cyl engines. Super overkill for your poor little 6 banger. "Be gentle with me! I'm just a pretty girl" The only hope is a common mode choke on the 12V AND ground wires on the radio.. such as https://www.amazon.com/WORKMAN-NF-40-STEREO-FILTER-HANDLING/dp/B00IJZWWWM/ref=sr_1_6?ie=UTF8&qid=1543887672& sr=8-6&keywords=radio+noise+filter There are many listed, but no guarantees.. it might only improve thigs but not eliminate. You may be up against a noise level so high that filters cannot take it out.. You might also try using resistive wires with your MSD.. but we are off of the reservation there.
Thanks for the insight and tips Chris. I would just like to remove it I think and go back to stock. I will just need to get a list of parts I would need. The plug wires all just look stock-nothing special.
Most "Performance" coils make more problems in the short and long term. Example with old Distributors often burns out the caps and rotors. That can "Back Feed" the coils and kill the system. Or the dying parts can "short" HV to Ground inside the dist and kill the system. (Some here have Short Wave, CB, and other 2-way radios? "Back feeds" can = to unterminated or mismatch cables/connectors/antennas causing High SWR killing them.)
MSD box is a scam and push for 40+ Decades by so called "experts." You have to know what Spark Dwell actually means and what it does. In a nutshell... Spark Dwell is how long the Actual Spark last. While you often can't measure or see the spark when looking, engine scopes etc can see the difference between the systems. Normal ignition coils etc have a long Dwell makes the spark to last long enough to fire the fuel mix at all RPM. (Some may remember using a Dwell meter for old Points ignition. Measuring Points Dwell directly affect Spark Dwell but not quite same thing.) CDI hype of having multiple sparks because the short spark they generates can not fire the fuel mix at all RPM. Claiming give more power and/or MPG is a side effect at best but doesn't do either vs good stock system on street cars.
Originally posted by 88Fingers: Thanks for the insight and tips Chris. I would just like to remove it I think and go back to stock. I will just need to get a list of parts I would need. The plug wires all just look stock-nothing special.
Remove any "Performance" coil and use good wires etc. Wells and Standard makes most ACDelco, NAPA, AZ and other big chain coils and ICMs. Good wires often do not = 8mm etc wires.
Note that MSD box/coil isn't only thing could kill ICM... ICM death is often a symptom not the root cause. Examples: Iffy part(s) anywhere on HV side can "back feed" the coil and fry that and the ICM. Iffy ICM mount screws can kill it too because 1 or both screws are the ground for it and rest of HEI. (Most use only 1 screw there as ground.)
If you will permit me one clarification o great Ogre.. The dwell time is the time that the current builds up in the primary of the ignition coil. When the primary is turned off (points open or transistor turns off), the stored magnetic field generates a high voltage on the secondary, and thus a spark. So you are right, but technically, the length of dwell determines how much energy is stored, and then determines how big the spark is. To much dwell time? too much current built up. Too short of a time? Not enough spark strength. The CDI ignition is different.. a big capacitor is charged, and an SCR is turned on, grounding one end of the cap and shifting that big charge across the primary of the coil.