1982 SC missfire when run hard.
 

The SC runs very well but recently when I've been taking it out for a spirited drive with revs around the 5,000 to 6,000 mark, after a few minutesI get a missfire.

After I back it off and drive around at the 3,000 to 4,000 level it come right after about five minutes.

The missfire is across the whole rev range. It's always had a missfire when it's under 2,500 and I give it more than half throttle, but I never worried about that.

The fuel filter is only 500 miles old and the plugs are clean.

When I take it out for one of these sessions it's been driven for more than half an hour before I do the 5k 6k rev's thing, and it's fine before that. The temps don't ever go past the horizontal mark on the gauge. It didn't used to do this :(

I don't have CIS pressure measuring equipment :(

What are your thoughts?

I think my brother had that problem and it ended up being his distributor was worn. I think he put in new bushings IIRC and it fixed the problem. I guess he found out the SC's were known for distributor problems later on in life.

Hey Bill,

At night, open the trunk lid after a good warm-up drive and look for arcing.

I had that problem, and my plug wires appear to be old, and where coming off the plugs.

Thanks guys.

It could well be an electrical problem. Fuel seems to be either yes or no, the car goes or it doesn't. This the harder I pushed it the gradually the worse it got. Then when I backed it off it slowly and evenly got better. Umm, six months ago the harder I drove it the better it went. I'll re-phrase that. If I drive it hard it goes really well. Blows the cobwebs out etc. Then after a while it gets the missfire. One day I gave it a good high speed, high rev, session and thought I was going to have to walk home. If it was my old Ford escort I'd swap out the coil and condenser just to be on the safe side. As soon as it's dark (New Zealand time zone) I'll fire it up and look for arching. Again, thanks for your support.

My thoughts are like Cabmando's - when things heat up, the distributor advance sticks a bit. Doesn't take much bind to reduce the advance. Could be other things, of course.

I have a 82 SC also and it would miss just like yours when I first got it. I looked it had the original plug wires and the plugs electrodes were almost burnt off! New cap, rotor, plug wires and plugs and now she revs nicely with no misses.

you are eventually going to work your way back to coil and CDI unit .. lots of other things to check first tho do you have original Bosch or permadoom .. just had a buddy with your EXACT symtoms .. turned out to be permadoom..

Thanks guys. No fireworks.

But I'll pull off the leads and distributor cap as a unit and resistance check from end to end. I did this a few years ago and it was fine. But I'll check again.

Good thinking re distributor. I'll look into that - out comes the Bentley manual I think.

If it is the CDI unit I have a spare one floating around so I'll try that too :)

My money would be on the distributor bushing / bearing.
Allows the rotor to move around, particularly at high revs.
Pretty easy to diagnose once the shaft is free of the case.

Do you have another coil you can try? I had similar symptoms and it turned out to be my coil crapping out at higher rpms..............when it got hot, if it cooled down it would work well............until eventually it failed completely.

regards,
al

if you have a spare cdi i would have popped it in already all of about 5 minutes to change