vetteset8087

My 87 mini ram 383 with sds ecu has no spark I need to test the coil in cap coil does anybody know how to. I was having intermitent starting problems now I have no spark at all. I really think it's in the coil when I replace the cap I found the coil loose in the cap and I had a bad plug wire it did start and run after the cap was replaced and I was having the intermitant problem before and after. the sds is a crank trigger system so it does not use the ignition module or the pickup coil in the distributor. so the problem has to be either the coil,the MSD 6AL, or a loose connection. I am planning to start with the coil because it's the oldest part in the system. Thanks in advance for any help

jfb

Place a .05 Mfd to .1 Mfd capacitor across the primary, use a capacitor from an old points type distrubutor if you have one. Then pulse 12v across the primary, you should easily get 1/2 inch or longer sparks out of the secondary.

Demonic85

You can actually ohm it too. Using a multimeter probe the tach and battery terminals and it should read 0 resistance (ohms), if its anything else its likely bad. I found out I had a bad one this way while replacing the cap and rotor.

vetteset8087

Ok I took the coil out and ohm tested it I got .4 ohms. before I took it out I tried to start the car and it started idled ok turned it off and it tried it again it started the third time no start no spark. I do have a signal from the crank trigger to the ecu so that eliminates that so now it's either the coil or the MSD 6AL. would you say the coil is bad with the info above?????

jfb

An ohmeter will find only gross defects. A spark coil is no good if there is a turn to turn short in either primary or secondary and an ohmeter cannot find that. A better instrument to use is an impedance bridge which measures inductance and coil Q but you would have to know what those values are to compare them to what you measure. The best test of all is the one I recommended, all you need are two clip lead wires and a capacitor and you can find out if your coil is good or bad!
If you still have the original spark control module in your distrubutor you can hook that up and see if your engine starts and runs, that will eliminate the coil. Also, If you are using the OEM coil, you are making a mistake because it was not designed for capacitor discharge ignition which is what your MSD system is and if you want to keep the MSD, then buy their spark coil and install it.

vetteset8087

I am using the MSD 8225 spark coil. I did the ohm test but still can't confirm if it is good or bad. I am going to reinstall it and do the MSD 6AL test from the msd website which still won't tell me if it's the MSD or the coil but I will try it. is it common for a coil to work sometimes and not others more like work when it's cold and not work when it's warm or hot?????

jfb

It is rare for a spark coil to be intermittent. Usually when they fail they stay failed. For the life of me I don't understand why you are resisting the very simple test of pulsing the primary with 12v from your car battery as I described and see if you get hot sparks.

Demonic85

jfb is right, if its intermittent then its more likely to be a short or possibly even a dying ignition module. However, a new coil is only like $10 if you need one

vetteset8087

I did the MSD test and have plenty of spark by grounding the white wire from the MSD 6AL so the coil and MSD are fine I sent an email to SDS the ecu manufacturer but I have not heard back from them yet. jfb in your original post for some reason I did not understand what you meant but after reading your reply and doing the MSD test it made perfect sense: For the life of me I don't understand why you are resisting the very simple test of pulsing the primary with 12v from your car battery as I described and see if you get hot sparks. I will let you know what it turns out to be. I don't know why this car is such a pain in the *** everything has been replaced in this car seriously including the engine 2 times trans once rear end once alt starter ps pump rack fuel injection system ecu dist paint interior sound system suspension and I have only put 6,000 mile on it since I owned it now the stuff I replaced is going bad