need ideas random missing

wbedwards

wbedwards

Senior Member
I am having a random miss on what is probably a bone stock '59 Edsel with the 361 FE engine. It cranks easily and runs fine most of the time but occasionally gets a random miss most often from coast to moderate to hard acceleration. It idles fine at 500. It missed at idle one time bad enough to load up the muffler and blow it out when it fired.
I was shooting for the easy things first. In the past 10 months I had to rebuild the carb and replace the tank. The fuel lines and filter are clean. Replaced the plugs, wires, points, condenser, rotatory button, but not the cap, it looks fine. The coil resistor ohms out good and coil is getting 5.8 volts. The dist primary wire is good. The plugs are mostly brown but a couple are getting some soot on them and the exhaust where it hits the ground in the garage is sooty. The timing is spot on 6 degrees and it has a new spark advance.
Two things bother me:
The spark is more purple-red than fat blue and the compression. I might try replacing the coil next.
I pulled the compression and its low, but not low enough to miss-fire I think but would like your opinion. The factory spec is 180 lbs and my readings are as follows first reading and then with a shot of oil: 1 152/154 2 140/145 3 140/145 4 139/144 5 130/136 6 130/135 7 140/142 8 140/146. Using a infrared thermometer on the exhaust manifold, #4 is running a good bit cooler than the rest upper 189 as compared to the others 215 at idle.
I have put about 1500 miles on it since I bought it and it has not used a drop of oil that I can tell.

thanks ahead for any ideas
 
could be the cap. had the same problem once on my dads I.H.C. Scout. replaced the cap and cured the problem. I could not see anything wrong with the cap, but a new one cured the problem. not saying this is your problem , just an experience I had, and an option.
 
You may be right. I hate just throwing parts at one, but that is what I'm reduced to now.
The spark is just not hot blue like I would expect, but more purple-red. The #4 is the longest plug wire and also the one that I think its randomly missing on.
 
I know what you mean about throwing parts at a problem and hoping for the best, been there. as far as the color of the spark, if you had another coil laying around, you might try that. if you don't, maybe a near by friend has one you could try..
 
I tried another coil, but it was a Lucas from an MGB from the 70s and it was worse =[ Prob why I had the coil left to begin with. =]
 
if it misses often at idle you can use and induction timing lite on each plug, may take a little while to check all the plugs, but hopefully you can find the plug thats missing, when you do find it the timing lite wont flash at the plug
 
Try changing spark plugs from 4 to 3 or 2, which ever is easier. Often, one plug out of 8 can be bad. If that changes nothing, try the same with the wire to 4.
 
Well...I replaced the coil and cap tonight and it ran smoother and didn't miss or burp on a 5 mile ride soooooo I put it away for the day to bask in a small victory. It shows me you can't use a ohm meter to tell anything about a coil. I thank you guys for taking the time to read and make suggestions.
 
Sounds like the coil fixed the problem, but you mentioned 5.8 volts to the coil. It seems to me that everything I have owned ran from 8-10 volts when the engine was running. I think you might benefit from a new ballast resistor
 
craig said:
Sounds like the coil fixed the problem, but you mentioned 5.8 volts to the coil. It seems to me that everything I have owned ran from 8-10 volts when the engine was running. I think you might benefit from a new ballast resistor
Click to expand...

Even though it is running better I checked the voltage and you are right. It was still 5.8 volts. I took the engine ground to the firewall loose and it was corroded so I cleaned both ends. Then I took the resistor off and cleaned the connections. The connections are just pop riveted on so I worked them to clean them up then took a punch and staked them very tight. Now I can't move them as I could. Took a voltage reading after that and got 9.8 so that was a MAJOR improvement. Thanks for the idea. I may not have needed a coil at all but its all new now. It is running much smoother now.
 
It sure sounds like you've got the low ignition voltage problem figured out. I'll guess the spark looks better too.

Is the other end of your battery 'ground' cable bolted to the engine? It won't hurt to make sure that connection is clean also. Having the (-) cable bolted to the engine usually works best for the starter, and the ground strap from the engine to the firewall grounds the body and all it's lights & accessories.

I had a leftover ballast resistor with a similar loose rivets / bad connection problem and soldered the rivet heads to the terminals. It works fine now so I hung on to it as a spare.
 

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I cleaned the other end of the strap as well. I also have a strap I added to the front of the car from the battery too. I've seen grounds or lack of do some strange things but it didn't dawn on me that was probably why my spark was weak.
 
wbedwards said:
I've seen grounds or lack of do some strange things .....
Click to expand...
Like quad headlights with one on normally and the other three being orange. Or tail and brake lights that only half of them seem to work but they switch sides when you step on the brakes.
 
Had a seemingly untraceable issue. Ended up 2 new sparkplugs went bad, with spark jumping allover but where it sould.
Did you get to try oledon's hint?
 
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No, but that was a good idea. I think I'm good for now. It ran better last night than it has since I've owned it.
 
"Sounds like the coil fixed the problem,"



If replacing the coil and cap fixed the problem, I would bet it was the cap and not the coil that was the problem. Caps with cracks and/or carbon tracking can cause the popping in the exhaust (or intake).
Also it's best to change one thing at a time when trying to diagnose, or you may never know what the problem was.

Sal
 
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