engine backfire and popping in the headers

[6spdYJ]

Great input Art. Check to make sure your coil is wired correctly, if the polarity is backwards you only get 1/2 output from the coil.

[neilbyrd]

Lack of fuel it would just hold back, vapor lock when it's severe it will just quit and you will have a hell of a time getting it started. It's a stick shift right? Try this for the heck of it, works pretty good for doing a quick check of your ignition system.
Barely get it rolling in first gear then stick it in third and floor it, skipping second. You want to barely start the Jeep rolling then go to third gear and floor it to really get the engine chugging if it is backfiring you have an ignition problem. I.E. not enough secondary voltage to fire the plugs

Will this work with my setup 40" iroks, 4.56 gearing, t18 trans. I will try this tomarrow. So let me get this straight, start rolling in 1st(barely moving) go to third floor it and if everything is ok there should be no backfiring. I assume there will be pinging(detonation) is this correct.

[neilbyrd]

Great input Art. Check to make sure your coil is wired correctly, if the polarity is backwards you only get 1/2 output from the coil.

The coil is wired correctly and the nuts are tight.

[aw12345]

Lol plenty of loose nuts around, me included
Seriously, it's kinda important to figure out of it's fuel or ignition related.
Try to get it up to 210 degrees on a flat road and see if it acts up too.

[Lumpy Grits]

When you do this "load-test" spray your ing wires with soapy water and see if it gets worst(cross-fire). I'm starting to see more of an ing issue than fuel.
When was the last time you changed the dizzy, rotor and wires?
Be sure that you do not have a vacum leak somedangplace that will cause a lean out condition and will lead to running hot also.
Respectfully,
LG

[neilbyrd]

Lol plenty of loose nuts around, me included
Seriously, it's kinda important to figure out of it's fuel or ignition related.
Try to get it up to 210 degrees on a flat road and see if it acts up too.

When i am driving on flat road it wont get up to 210 only on the long hills. By long hills I am talking about steep and about 1 mile or longer. As far as fuel or ignition I use to think it was fuel, the plugs were wet and black to start out jetted down 3 sizes now they are clean but pinging( before you say anything about the ping I am moving up 1 jet size today). So I kinda think it's ignition, I have been to both ends of the fuel scale and it acts the same either way.

[neilbyrd]

When you do this "load-test" spray your ing wires with soapy water and see if it gets worst(cross-fire). I'm starting to see more of an ing issue than fuel.
When was the last time you changed the dizzy, rotor and wires?
Be sure that you do not have a vacum leak somedangplace that will cause a lean out condition and will lead to running hot also.
Respectfully,
LG

I changed the cap, rotor, points, condenser, plug wires, spark plugs, and put in a accel 45000 volt coil all in the last couple months. I will try spraying the plug wires today and doing the laod test. The think is that the jeep runs fine an the street and at street temp until I come down off the hill while it is having one of its episodes, then the longer I drive it (on the street) the better it gets. Its like the cool air blowing through the engine is cooling something. As far as a vacuum leak I only have one vacuum line and that one goes to the dizzy. The brakes are hydro.

[6spdYJ]

What condidtion is the radiator in? If street speeds keep enough air moving through to keep it cool, but the fan can't pull enough air at trail speeds it can cause heating issues. Also, where is the temperature pickup located? The most accurate will be as near the last cylinder cooled (such as #8 on Chevy's). If it's at the thermostat housing, it can be reading cooler than the rest of the engine.

[Lumpy Grits]

How hot is that coil getting?
If you can't keep your hand on it then that's to hot.
Respectfully,
LG

[Jeeperator]

Its not vapor locking if it was the plugs wouldnt be wet and sooty and it wouldn't back fire because that is caused by excessive fuel igniting in the exaust. The jeeps got a v8 with probably a somewhat small radiator because its a jeep. Some higher temp are to be expected when
going up steep hills. Shoot! mine get to 230 and still runs fine 210 is perfectly normal and shouldn't affect the way it runs IMO.

LG made a good observation about the coil, is it getting too hot?.When a coil over heats it can cause similer problems. The coil should be hooked up as follows + on coil should be positive switched 12volts with a RESISTOR inline. The -on coil should be coming from the trigger or points of the distributer. There is also a wire usually coming from the starter that supplys a full 12volts to the + side coil only when your cranking. I personally dont like accel coils as I have heard people having issues with them in the past. Maybe change it out and try another brand or stock. Try this, drive up the long hill and as soon as it starts running bad pull over and check the coil and see if its hot. Pop the hood and let it cool down for about 20 minutes and start it back up and try to keep going up the hill. If it runs good for a while it has to be ignition related.

[Lumpy Grits]

Jeep CJ's have a resistor wire in the OEM loom so don't add second one.......
Respectfully,
LG

[Jeeperator]

Jeep CJ's have a resistor wire in the OEM loom so don't add second one.......
Respectfully,
LG

I agree but who knows who wired it or if it is still in the factory loom. We must agree it should not have a full 12 volts going to the coil all the time.

[Lumpy Grits]

WELL.......MSD does.

[neilbyrd]

I will try to answer all the questions you guys just threw my way:
1.The radiator is new its aluminum 2 core 1" tubes and is wide enough it blocks to the middle of both headlights.
2.The temp sending unit is in the block driver side opposite of the dizzy.
3. Not sure of how hot the coil is getting, but I had a stock coil in it before and it did the same thing thats why I changed to the hotter accel. I will check the next time it is running bad.
4.The coil doesn't have a resistor going to it and I know who did the wiring (it was me a whole new harness so go easy on me)
5.I just finished the load test (1st to 3rd and floor it with soapy wires) and it chugged jerked and kept going. I did it a few times and same thing ever time, even got it do die once. It never backfired.

[Lumpy Grits]

Just for "grins"....
Park the Jeep in a DARK garage and with hood up spray the ing wires with a VERY soapy water AFTER the eng. is running and warmed up and look for blue arcs of light.
Go back to OEM stock Champion spark plugs and set the gap at .045".
Respectfully,
LG