Hi everyone I want to blow off some steam.My 87 Iroc with a 355 4bbl had a bad intermittent missing problem that started right at 3000 then only occasionally missing upwards of 3000.Puzzled at first I started the process of elimination with a new msd cap and rotor-no change at all,next a new set of msd superconductor 8.5 wires(my old ones had seen better days)their 8.5 superconductor wires are pricey but obviously a quality product,extra long and very low resistance.Still the same no change at all,with vaccum advance it missed with no vaccum advance the problem dissappeared.Sooo time for a new vaccum canister right??Still no change.Threw on another carb just for the hell of it ,same problem at 3000 and up.Tried a new pickup coil and ignition coil, no good.One thing left to try ,I disconnected my msd6al box and put the factory stuff back in..IT WORKED!! My f***ing 2 yr old msd 6al box that I paid $300can for was the cause of all this grief.IS IT JUST ME OR SHOULD A 300 DOLLAR IGNITION BOX LIVE LONGER THAN 2YRS?!?!my car looks like a poster child for msd products I thought they were supposed to be the best!!I am very dissappointed.just my .02cents

 

Even the best products can break. Could a different part of the car that was defective cause the msd box to fry--sure. Also, maybe the vacuum can was bringing in too much additional timing for your combo, with the msd box. If you want to be sure, stick the msd box back in and verify the miss, install a new msd box and see if the miss is gone--installing the stock stuff adds in some other possible problems.

 

you don't really know if it was the box or a bad connection and the parts do break and wear out. after 2 years i don't see where you can say MSD doesn't make a quality product. have you contacted them to have it tested? they have very good customer service.

 

Thanks for the reply 82camaro. The missing gradually worsened over two wks,it really had me stumped and I have always been a believer in msd until now that is.I tried everything to cure the problem convinced it was either igntion related or a vaccum leak and yes i played with the timing but to no avail.As a last ditch effort having already replaced everything else I disconnected the msd box.It was the culprit.

 

ede thank you for your quick reply...the box was mounted between the vapour canister and the driver side fender.(I moved the canister closer to the rad to make room)The power supply for the box went straight to the battery and yes I checked those connections as part of my process of elimination.I think a $300can igniton box from a company like msd should last longer than 2yrs and I dont think my expectation is unreasonable.

 

i mounted mine inside the car as far from engine heat as i could get it. i know someoen at msd ,i sent them an e mail and a link to this thread. we'll see if anything happens.

 

MSD's are notorious for failures. I've heard of people on thier 5th or 6th warranteed box. My fitst one went bad after a week, mine is mounted inside the car too. They're a great product performance-wise..but the durability sucks. On the other hand..MSD knows it so they are good about returns and repairs.

 

The ignition module in my msd distributor lasted less than a year, and I think the pickup is bad now.