so the past few days ive been having trouble getting my jeep to run correctly. i changed the intake filter to a cheap ebay one, made sure all the vaccum lines were on good and reset my map sensor. i changed the plugs right after i got the jeep a couple months ago. its been missing and running horrible lately, so i figured i fouled them out. so i went and bought another set of plugs (bosh platniums). it ran perfect as soon as i got them in and started it, then after it sat there and idled for a good while and got up to operating temp it started missing again and sputtering. it runs really rich and i just pulled out the new plugs and they are fouled out too. i also found that the vacum line from my map sensor to my throttle body wasnt conneted. would that have been why it was running so rich and why i am ruining spark plugs?
thanks for any help!


its got new cap, rotor, wires, and fuel filter.

 

Fix the map vacuum line. As far as plugs go don't waste ur money on fancy plugs, champions will work just as well in the 4.0....

 

^^^ Agreed my jeep seems to run best on the champion coppers.

The MAP sensor could very likely be the issue. So fix that first and see if it fixes your issue.

 

Alright guys, ill mess around with it and see if thats what it was.
thanks alot.

 

Let us know how it goes.

 

Definitely. With the hose disconnected the sensor sees atmospheric pressure. The closest it will get to that while running is if you are at an idle and open the throttle all the way. The inrush of air drops the vacuum, and the ECU compensates by sending more fuel.

If this is not the problem, check the O2 sensor.

 

Make sure your MAP sensor is plugged in securely, along with careful visual inspection of the vacuum line from end to end. How did you "reset" your MAP sensor?.

 

Bosch plugs are more than likely the problem. Bosch makes some great o2 sensors, but spark plugs not so much.

Go with Champion plugs, and if you still have problems, put in a plug 3 slots higher in heat range. (RC9YC to a RC12YC)

NGK -- those good too.

 

I just uplugged it and let it sit for a few minutes after I checked all my vaccum lines that I thought would be the problem.. Not realizing the one for the map sensor itself was disconnected.

 

ill put in some champion plugs, possibly an o2 sensor and fix the vacuum line.
i have an exhaust leak too..

thanks for the help everyone. ill let you know how it goes, should have time this weekend to work on it.

 

Not surprised.

 

So I finally got around to getting it back together. It runs great, just changed the plugs. Hopefully it stays running as good as it does now. On the flip side, I have a horrible transmission leak. To the point at which there is no fluid in it at the moment. I'm going to replace the filter and gasket and see how this goes. It started leaking after I drove it down the road and back. Ill clean it up underneath and try to pin point where the leak is coming from. Any help with this..?
Thanks.

 

A buddy of mine blew a cooler line on his once

 

I'll get under there and check them all, I know a couple of them are pretty rotten..

 

His blew the quick connect fitting on the tranny. The dumbass sat there for a few minutes in park with the throttle pinned though.