efficientkilla007

My jeep is idling absolutely terrible, and I can watch the engine kinda shake when it's running, and it's pushing a ton of air through my oil cap, and it sounds like it backfires a little too while it's pumping out a bunch of smoke through the tail pipe. Someone told me it could be the cat, but I have also read that if that is the case, the tail pipe should be sucking and not pushing out a ton if air like mine is, you can really feel the pressure coming out the tail pipe if you stick your hand over it. does that sound like a cat problem? it's been tuned up recently so Im not sure where exactly to start. I figured the cat or maybe and ignition could could maybe cause some of that too?

jomps

what color smoke?

efficientkilla007

Im pretty sure it's white, I think I would notice if it was blue, but I know I have bad piston rings so I've noticed some smoke here and there but never like this, usually the only time it smokes is from the oil cap. this all started with me driving down the highway and I suddenly wasn't able to speed up, I was still able to drive it home but it tried to idle down and almost die everytime I stopped.

brasscatz

At first I was going to suggest the IAC valve because my buddy's Jeep was smoking with a very rough idle.... new IAC valve fixed it up like new. However, the loss of power may change things.... has your cat been rattling? If so the brick could have come loose and clogged your exhaust. May cause your issue. Another issue I had was I spun a bearing in my old Chevy pickup and experienced the same thing. I'd take it to a shop and get an opinion... most shops will give their opinion free of charge... some won't. Have them check the temp of your cat front and back and see if there may be a clog...

highmileage

you can look for a broken vac line to your map sensor or a bad map sensor. had a similar problem and that was it.