I was driving home from school today and it's about 90 degrees out. I just replaced my radiator on saturday, and now my Jeep seems to be giving me more trouble. This time, I was driving and it was running fine. After I stopped at a light for a couple minutes, the Jeep misfired when I hit the gas and continued to misfire until I got to the top of a hill. After I was at the top of the hill, it never missed again.

I replaced the spark plugs with champion coppers and I also replaced the wires with MSDs back in april so that cannot be the issue.

Wild guess but could it have been vapor lock since it's so hot out?

 

Not to try to steal, im just joining in, i replacing radiator tstat and water pump a few weeks ago and it is now misfiring when i start it up until it gets to running temp, then seems to run normal, also replaced with champion coppers

 

Anyone know what this could have been? I need to know if I'll be able to make it to school and back tomorrow or if this is a major issue.

 

This is a guess....same thing happened to my metro....but it ended up being the head gasket. I would start it and it seemed to miss fire a bit the. I revived it up a little and it went away. It was coolant that seeped into cylinder one. Eventually....went on for weeks maybe months can't recall....had to replace the he'd gasket after it hydro locked. It was in the middle of winter so the car seemed to "smoke" all the time cuz it was so cold. But at first start up it was burning the little bit of coolant that seeped in. I'd do a compression test then go from there.

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Bad gas....water in gas. Replaced cap and rotor at all recently? Spark plugs and wires? Why did you replace you rad? Over heat it at all? Even a little? At certain temperatures you head gasket can let a little bit of coolant in...usually when running hot. But this could cause those symptoms. But could only last a short time. Compression test would help. Pull ur plugs and let us know what they look like and I'd any are darker then the other.

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I did just see u replaced ur plugs and wires not long ago. Pull the plugs though anyways.....all of them too. One by one. And see if any look unusually worn or dark.

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I replaced the radiator because the plastic tank upper hose fitting crumbled into a million pieces. It overheated when the hose fitting broke, I let the Jeep sit on the side of the road for a few hours and then I attached the upper hose as best as I could, added 3 gallons of water and drove home. It overheated a little when I was home but nothing major. My guess is the head gasket is fine so I wouldn't worry about it because it has been running fine all day except for when I was climbing that hill after being stopped at a light today.

I haven't replaced the cap and rotor yet but it's on my list of things to do.
As for the plugs, none of them look fouled.

 

Ok gotcha. Cap and rotor could be the problem. That would help. If you over heated I wouldn't rule out the head gasket. They can be fishy sometimes. My metro was over heated over a year before my head gasket went....previous owner "forgot" to mention that he over heated it after a house blew. He actually drove it till the motor just shut down....towed it and had the hose fixed and it was fine. Acted up here and there but never enough or often enough for me to think head gasket. Got worse and happened more often. Then I seen it coming. But drove it anyways. Runs perfect now tho. I never rule anything out in less in 100% sure. In this case you cant be 100% sure since you don't know what you head gasket looks like. You could do it anyways just to see. Lol...who does that pssshhhh.....

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It was still running alright when I turned it off when it was overheated. It started up just fine afterward, and ran fine on the way home. I was being pretty careful with it. Couldn't I just tell if my head gasket is going just by looking at my oil after doing an oil change? I don't want to tear into my engine unless I absolutely have to because it's my daily driver and I need transportation.

 

Ya you could check your oil and see if its milky at all. But if it only acts up once in a blue moon then it won't be milky. I'm just saying don't completely rule out the head gasket. I'm hoping its not it. I am having a problem with ky XJ smoking for a few seconds at highway speeds. It warms up after 40 min of driving to 235 degrees then smokes for like 10 secs then goes back down to about 218. Usually does it when I'm going up a hill or stomping on it after driving at 65-70 for awhile. I think its a head gasket issue but no significant coolant lose. No milky oil or brown coolant. But I'm still thinking that's it....but I'm not doing anything about it till it gets worse. So for you maybe do cap and rotor and see it it happens again.

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Hasn't happened since. Jeep is running fine now so I'm gonna wait till it happens to investigate

 

Finally figured out what caused the issue!

My return heater hose had a pinhole leak in it and it was getting my plug wires and distributor wet.

I replaced the hose today and installed new hose clamps, it's back to normal.

 

Sweet. Glad you figured it out.

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Yeah I'm glad it wasn't anything major lol