1966 289 Engine Misfire
5/29/08, 08:02 AM
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1966 289 Engine Misfire
I've been experiencing rough idle for quite some time on my 289 A code. I suspected a misfire so I began removing the spark plug wires one at a time to determine if a cylinder was misfiring. Sure enough I found that cylinder #2 was not firing. I've since tried many troubleshooting methods to try to find the cause. I've swapped plugs, plug wires, and coil without any change. I've also adjusted the timing. I ran a compression test on the left bank of cylinders and all four read at exactly 150 lbs. The carb has been rebuilt by Pony Carb so I know thats in good shape. I'm running a Pertronix II electronic module instead of points.
The only unusual thing that I've noticed is that while pulling the individual spark plug wires with insulated pliers I get a strong shock from the wire on cylinder #2 but this doesn't happen on any other cylinder. I put a brand new wire on #2 and it still happens. Any ideas or suggestions?
Thanks,
Larry Burke
The only unusual thing that I've noticed is that while pulling the individual spark plug wires with insulated pliers I get a strong shock from the wire on cylinder #2 but this doesn't happen on any other cylinder. I put a brand new wire on #2 and it still happens. Any ideas or suggestions?
Thanks,
Larry Burke
5/29/08, 12:51 PM
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Electricity takes the path of least resistance.
Have you replaced the cap? Are you positive that you have not damaged the new wire or the new plug installing them? Have you tried adjusting the timing just a bit?
Have you replaced the cap? Are you positive that you have not damaged the new wire or the new plug installing them? Have you tried adjusting the timing just a bit?
5/29/08, 01:10 PM
#3
Tasca Super Boss 429 Member
Maybe grab another old good wire and try it on #2 or exchange with another wire and see if the problem moves or goes away.
5/29/08, 01:12 PM
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Ralph, I'm pretty sure that the plugs and wire are in good shape. The plug wire that I tried last night was brand new out of the box. The same result happened with the new wire as the old one. The moment that I removed the plug from the spark plug while the engine was running there was no decrease in RPM and I begun getting seriously jolted from the wire although I was using insulated pliers. The other plug wires don't do this. I also played with the timing and it doesn't seem to help.
I haven't tried replacing the distributor cap yet. It was replaced two years ago so I was assuming that it was in good condition. I will try a new cap to see if that fixes the problem.
I haven't tried replacing the distributor cap yet. It was replaced two years ago so I was assuming that it was in good condition. I will try a new cap to see if that fixes the problem.
5/29/08, 01:23 PM
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I did find that the #2 cylinder plud wire at the cap was damaged although it was new. Upon removing the plug wire at the distributor cap end I noticed that the wire core was never crimped onto the metal terminal. Basically the core wire was hanging suspended inside of the metal terminal never allowing direct contact with the distributor cap. The inside of that particular cap post is blacken due to the arcing that was taken place. Maybe it damaged the cap itself in the process.
5/29/08, 02:46 PM
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I call that infant mortality. karman hit it good there.
I remember a long time ago one that stumped me. Had a small fire under the hood. Replaced all rubber (wires, cap, coil, etc.). Couldn't get any fire. After working for a long time, started tracing and found that the brand new coil was dead.
Never trust a part just because it was "taken out of a new box". That is why you said "pretty sure".
Let us know how it runs, Larry.
I remember a long time ago one that stumped me. Had a small fire under the hood. Replaced all rubber (wires, cap, coil, etc.). Couldn't get any fire. After working for a long time, started tracing and found that the brand new coil was dead.
Never trust a part just because it was "taken out of a new box". That is why you said "pretty sure".
Let us know how it runs, Larry.
5/30/08, 10:12 AM
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OK, I've replace the cap, rotor, coil, and spark plug wire on cylinder #2. Still not firing! I'm still getting a lot of arcing on the outside of the #2 plug wire and shocks when I pull it off of the spark plug. This doesn't happen on any of the other cylinders. The problem appears to be isolated to #2. Any thing else to check?
Larry
Larry
5/30/08, 04:45 PM
#11
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What you seem to have is a a wire looking for an easier path to ground than going down to the plug.
This should have been done when replacing the wire.
What wire did you replace it with?
Arcing on the outside indicates the wire may have damage.
If the wire that is in there now has arced before or is brand new, it may be NG.
Am I to understand the other wires tend to just zap to the center of the boot from the plug?
Also have you double checked the #2 sparkplug and gap since you noticed the #2 problem?
What wire did you replace it with?
OK, I've replace the cap, rotor, coil, and spark plug wire on cylinder #2. Still not firing! I'm still getting a lot of arcing on the outside of the #2 plug wire and shocks when I pull it off of the spark plug. This doesn't happen on any of the other cylinders. The problem appears to be isolated to #2. Any thing else to check?
Larry
Larry
If the wire that is in there now has arced before or is brand new, it may be NG.
Am I to understand the other wires tend to just zap to the center of the boot from the plug?
Also have you double checked the #2 sparkplug and gap since you noticed the #2 problem?
5/31/08, 04:22 PM
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All of the other wires arc from the center of the boot to the spark plug without any outside arcing when the boot is pulled from the plug. The #2 cylinder immediately begins arc and shocking me the minute I pull the boot from the plug. I tried a third brand new wire on the #2 cylinder today and it did the same thing. I replaced the plug and made sure that the gap was 0.034 before reinstalling. I don't have point on the car as I replaced them with a Pertronix II unit. This is really baffling me!
5/31/08, 04:26 PM
#13
Super Boss Lawman Member
this is confusing. did you check your firing order? I posted again on another forum and still trying to get an answer for you.
Last edited by BA Mustang; 5/31/08 at 04:30 PM.
6/1/08, 10:31 AM
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I swapped several spark plugs between cylinders checking the gap before reinstalling them. It always the same results. The plugs work in all of the other cylinders just not #2. I checked the firing order several times just to satisfy myself that some how I messed that up. The strange thing is that all of the other cylinders run fine and show a definite drop off in RPM when the plug wire is pulled. The problem appears isolated to just that one cylinder. I assume that if the timing or firing order was off I would see similar problems in the other cylinders. The arcing on cylinder #2 plug wires is really strange. I have two new sets of wires and no matter what plug wire I put on #2 is the same result; arcing and shocks!
6/1/08, 10:50 AM
#17
Tasca Super Boss 429 Member
So far...
Plugs are good
Spark is coming out of distributor
Have you tried plugging in a new wire of similar length from another cylinder?
That is, grab one from the new set that is not on the car and replace #2 wire with it.
Plugs are good
Spark is coming out of distributor
Have you tried plugging in a new wire of similar length from another cylinder?
That is, grab one from the new set that is not on the car and replace #2 wire with it.
6/1/08, 02:12 PM
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I just replaced all of the wires on the car with a new set to see if that makes a difference and figured that it would be one more check of firing order. Still the same results. Before changing all of the wires I did try different lengths and that didn't help.
I'm a pretty good distance from New Market. I live in the Hampton Cove area.
I'm a pretty good distance from New Market. I live in the Hampton Cove area.
6/1/08, 08:23 PM
#20
Super Boss Lawman Member
Here is yet another answer from the other forum
The Pertronix wouldn't fail on one cylinder only. When they go, they either die altogether or produce intermittant spark. The unit doesn't know which cylinder it's firing. The problem has to lie elsewhere.
First problem I see is that cylinder #2 is on the right bank, and the compression check was on the left bank
This is likely a simple misunderstanding of which bank is which, but it's something to look at.
With the arcing problems you're getting with the #2 wire during the balance test, it sounds like an ignition problem. For some reason the spark isn't crossing the plug gap, so it's trying to find the next closest path to ground, which happens to be through your hand. What you really need is an ignition scope, but we'll have to deal without one. Pull the #2 plug, attach it to the plug wire, set the plug housing against the block and crank the engine for a second. If you get a nice clean spark, it's likely fuel or compression related. Come back with the results.
First problem I see is that cylinder #2 is on the right bank, and the compression check was on the left bank
This is likely a simple misunderstanding of which bank is which, but it's something to look at. With the arcing problems you're getting with the #2 wire during the balance test, it sounds like an ignition problem. For some reason the spark isn't crossing the plug gap, so it's trying to find the next closest path to ground, which happens to be through your hand. What you really need is an ignition scope, but we'll have to deal without one. Pull the #2 plug, attach it to the plug wire, set the plug housing against the block and crank the engine for a second. If you get a nice clean spark, it's likely fuel or compression related. Come back with the results.