msd issues. 6AL going bad?

anybody experience this before? i have the msd distributor, 6al box with the tach adapter and a reproduction in dash tach.

I'm out cruising with the wife yesterday. the tach starts bouncing around a bit. I'm stopped at a light and i notice the car is idling high, like 1500 rpm or so. hard to tell since the tach was acting up.

pulling away from the light and the car is spark knocking hard. wtf?? engine temp is 170 or so. it occurs to me that the timing is way advanced all the sudden.

so while driving i turn the key off (4 speed car) too stop the engine thinking the advance weights were stuck?

it wouldn't restart. i tried to crank it over with the starter and also pop the clutch since we were going 40. no dice.

after we stopped with the key on and engine off, the tach was reading 4k. i popped the hood and the tach adapter is buzzing like an old phone. no big deal, i yank the tach adapter plug thinking I'm in pay dirt. still no start.

out of pure hope i unplug everything i can with the msd box- both leads on the coil and the distributor. i hop in the car and it roars to life sans the tach.


we drive another 5 minutes and the timing goes haywire again and advances like crazy and starts pinging like hell.


the car was parked for 5 hours. we hop in to go home and it behaves perfectly normal. it was an hour drive home. no tach of course.

so what gives? there is no question its an electrical issue with the msd. did the tach adapter go nuts? can the msd box increase the timing like that on a failure?

the repro tach has always sucked.

the msd box is 10 or 12 yrs old.

any tips?

thanks

 

i just pulled the cap. the coil post out of the distributor is worn away to nothing. it's actually burned away some. it looks like the spark is jumping to the rotor. I'll replace those for sure.

the weights moved good and free, no obvious failure with the pick up. I'll have to Google and see if there are some resistance values for it.

also, i plugged the tach adapter back in, that worked fine again

 

I replaced my old MSD box this winter. I didn't have same issues you describe, but they changed around. Convertible was getting hard to start. But after starting it was fine it seemed. Almost left me stranded once, but finally got it to start and after I got home, that was it. No more spark ever. Got a new one and perfect since. I guess they have a mind of their own when failing.

 

Interesting, I will keep a close eye on my MSD cap . Jim

 

Had a couple of the old AL6 boxes go bad. One was fixed by MSD but later died again and then the other died. MSD said they were no longer supporting that box. One just up and died the other started doing weird crap.

 

the coil and pick up both passed a resistance test. i suppose the box itself is to blame.

 

If the box is disconnected, how can it still cause problems?

Apparently you have an MSD Ready-To-Die distributor that's acting up.

 

Those are horrible distributors. I went through 5 before I went with a DUI For my shop truck. My buddy bought one for his Mustang, lasted all of 10 miles.

 

apparantly not. I unpluged the pick up and coil and plugged them back in... how would you expect the engine to run with the coil and trigger unplugged?

 

Based on you not mentioning re-connecting the box, I made an assumption: You disconnected the box, so that the engine would then run on the R-T-D module in the distributor.

WHAT distributor do you have? WHY have you not mentioned that in your opening post?

 

hahaha. any partucular reason you are so damn condescending all the time? a man of your knowledge would surely be able to deduce i have a pro billet distributor at this point....

 

larry- I'm getting a new cap and rotor tomorrow. it did seem to cure itself simply by letting it sit for a couple hours. while the cap and rotor are worn, i don't think thst is the root of the issue.

the weights in the distributor moved good and free. correct me if I'm wrong, but the box is the only thing that could throw the timing around and cause the tach to go nuts. it was reading 4500 with the engine off.

did the tach adapter fail and take the box or did the box fail and mess with the tach?

 

plugs are gapped at .045 i think. i certainly hope that solves it, but I'm skeptic. i get your bouncing around scenario, but it was idling about 1500 rpm too. usually when the spark is jumping it won't run at all.

 

I will. in the meantime I'll toss my ready to run points distributor back in the trunk. we're buffalo bound for the 4th.. hate to walk some of it.