MSD Problem

[Grip64]

Got a strange one here fella's, just finished pluming in a Msd 6al as per instrutions, car start's and run's fine, but if you hold the throttle at say 1500rpm or higher, the motor drops around 100rpm every two seconds or so, then rises back to 1500rpm, this is an even drop in rpm not all over the shop 

There is NO vacuum leak on the motor, its like a spark thing, Msd is NEW out of the box.

Anyone ever had this before ?

Run out of things to try 

[Ghoste]

Anything else changed at the same time?  Distributor in good shape, esp the advance?

[Cooter]

It would help if you could tell us EXACTLY what you have wired and how (Read: Diagram) and what type distributor, what Rev limiter pill you have in the box, etc...With little to no info, it is VERY hard to disgnose...I myself have never had the problem you are having, but I might be running something you are not...

[Grip64]

Thanks for your reply's fella's.

Ok its the MP distributor in good condition, timing is locked out at 32', Msd is plumed in as per instrutions using the MP distributor.

Got the 6000 pill fitted, Msd install is the only thing changed, not using the ballast resistor.

The problem is there with motor hot or cold 

[firefighter3931]

This sounds more like a distributor issue. Are you sure it's locked out ? From your description it sounds like the advance mechanism is functioning intermittently. 

Try removing the 6k pill and see if there's any difference. Another thing to try is swapping the distributor wires...i had to do this with my 6al to get it to run properly. For some reason the MSD boxes are often wired backwards for the MP distributor pickup. The proper polarity will be found using your timing light 

From the msd site : Check the polarity of the magnetic pickup wires of the distributor. Reverse the connectors and check the timing again. The correct polarity is whichever connection gives the most retarded timing.


Troubleshooting :  http://www.msdignition.com/page.aspx?id=3306



Ron

[Grip64]

Thanks for that Ron, will check it out over the christmas break and get back to you 

[Grip64]

Well Ron finally got these test's done, its not good news......

Yes the timing is lockout, the dist wires are on the correct way for the lowest retard reading, and removing the 6k pill made no change, still droping the rpm's 

I'm thinking could this be a faulty unit  

[elacruze]

Got a strange one here fella's, just finished pluming in a Msd 6al as per instrutions, car start's and run's fine, but if you hold the throttle at say 1500rpm or higher, the motor drops around 100rpm every two seconds or so, then rises back to 1500rpm, this is an even drop in rpm not all over the shop 

There is NO vacuum leak on the motor, its like a spark thing, Msd is NEW out of the box.

Anyone ever had this before ?

Run out of things to try 

Regulator kicking in and out, loading the alternator? Check the voltage at the battery and see if it rises/falls with your RPM.

[firefighter3931]

Got a strange one here fella's, just finished pluming in a Msd 6al as per instrutions, car start's and run's fine, but if you hold the throttle at say 1500rpm or higher, the motor drops around 100rpm every two seconds or so, then rises back to 1500rpm, this is an even drop in rpm not all over the shop 

There is NO vacuum leak on the motor, its like a spark thing, Msd is NEW out of the box.

Anyone ever had this before ?

Run out of things to try 

Regulator kicking in and out, loading the alternator? Check the voltage at the battery and see if it rises/falls with your RPM.

This is good advice...make sure you have a constant 12V or the MSD box will act wierd. The main red wire should be connected directly to the battery....not a "switched" power source. I usually wire them up to the starter relay stud.

Let us know what you come up with...



Ron

[Grip64]

Ok with the motor held at 2000rpm and the rpm's rising and falling, the battery is showing 14.8volts, with no change in volts.
The main red wire is on the Battery isolater switch along with all the other supply (battery in the trunk), i did wire the main red wire direct to the battery, but got the same results 
One more thing the Msd unit buzzies when the engine is running, is this normal ??