MSD ISSUE... backfires w/no power at all
 

Ok, before I started the car was running great. (never should have started this)

Car: 1979 911 row 3.0

parts:
MSD 6AL
Magnecor Wire 8.5
new plugs gaped .42" or 1.05mm
MSD blaster 2

Issue:
engine idles ok, but backfires with almost zero power under any load.
I check the pickup wires they are correct.
each of the plug wires is firing
I adjusted timing forward and back no go.

fried two rotors could this the cause or the effect?
I need help, I have two 5yrs old's that want to be in the 4th parade.
http://www.freeimagehosting.net/uploads/e74d9bf6a7.jpg

yank the MSD and use the original bosch unit. why do we need these things? the rotor resistor can be dremelled out and a length of solid wire laid in there and then JB weld over the top. sometimes the multi-spark doesn't change over to normal spark at 3K rpm and you get total crap-out/backfire.

I agree with john statement but in all honesty you probably have the polarity hooked up backwards. switch the 2 wires and you will be all set

I did switch the two wire at the distributor. Runs worse.

this is really frustrating.
for such a simple install, this is really troubling.

That sound exactly like what my car is doing with the new MSD. So I just ran over to Checker Auto and purchased the recommended:


Niehoff Ignition Distributor Rotor


It has the solid metal top with no resistor built in. I don't know that my rotor looks like yours but your description fits to a tee. Tomorrow I will go to the shop and see it that is the problem. If it is I will let you know.

Thanks, please let me know. I am going to do the dermal and wire install tomorrow.

Vhat das dis do?


KT

The "Niehoff Ignition Distributor Rotor" Is a rotor the same as a stock 911 rotor but it doesn't have the "resistor' built in...

Rebe911,

You have too much resistance in the system. Lots of us are using MSD, but as John suggests, maybe yours isn't working correctly. If the correct rotor doesn't help, change the plug gap back toward stock and see if that works.

You also mentioned playing with the timing. Set it so that it is correct at 6000 RPM, and don't worry about where it lands at idle. At least then you won't have to worry about the timing being part of your issue.

thanks I will give it a try.

have you checked the mixture and the advance even though you said it was running good before? it could be too lean especially if you have changed the timing and/or changed the CD unit. i would turn the mixture CW jsut to the point of surging or to the point the RPMS want to drop when you let off the gas and it returns to idle. for mine, i have found that edge where the dip in RPMS is, is 3%

Stupid question but does the engine need to MSD Tach Adapter to run correctly?
I would think not.

does it need the tach adapter for the engine to run correctly or for the tach to run correctly?
engine- no, tach- i think so but not sure.

im having issues with mine also. Im going to look for that rotor here in Austin. Is there a recommended plug and gap to use with these MSD's. I have the mm magnecor and a blue coil. my cap and rotor looked worn out after only about 2-3 months!!!:confused:

I had to put the tack adapter on my 80 SC with the MSD unit.

My tack is actually reading right.
it is just the engine is running like $hit. I am going to do the rotor mod tonight and end up the center tab on it for better contact. I believe there is to much resistance in the cap so the spark is happening in the cap once the MSD changes from multi spark to one big spark around 3k

did you clip the wires to set it up in 6 cylinder mode?

I clipped the red wire.

it may be just too lean

What's the plug gap set at? MSD recommends no more than .06" and in a Turbo this may be to wide. I'd set the gap at spec for your car and start with that, then only open up the gap after it runs correctly at spec. Keep in mind that the higher the cyl pressure the harder it is for the spark to jump the gap and your worse conditions are at your peak torque RPM in WideOpenThrottle. Given your description it seems to act up even at very light load just off throttle so this sort of indicates something else may be going on here. Could it be the MSD is somehow not setup correctly? check the basics, like cyl # configuration set to 6cyl mode?