For a few months now my mini has been misfiring, but I replaced the spark plugs, wires, and the coil pack, and still doing it. What else could cause this?

 

Perhaps a clogged injector.
When is this happening? Under load, at idle, high RPM? Is it consistent, or intermittent? Any codes when you scan the OBDII? Remember, there could be pending codes without a CEL, so scan it regardless.

 

Oh wait, aren't you the overheating guy? I'd do a compression check stat! You might be looking at a burned exhaust valve, cracked head, or blown headgasket too.

 

Hard to tell. The code that came up was random misfire. Seems to idle just fine after its started. It does take a few seconds to start it compared to other vehicles, and how it used to be. At high rpm's its fine never had issues at high rpm's.

 

Definately no blown headgasket, or any of that. Car has had the misfiring code for months before that.

 

I'd check compression just to be certain. My Dodge Ram 5.9 has an intermittent cylinder 7 misfire due to a bad intake manifold plenum gasket. It idles rough, but runs super smooth at anything off idle, and passed state emissions testing this way. I was afraid I had a cracked head, which is common on the 5.9 Magnum. I'm probably going to do the gasket tomorrow. I have a new tradition of tackling decent sized jobs on my bday. Last year, I pulled the engine out of my Cooper. Come to think of it, I just realized I've had my Cooper for a year and a week :-)

 

What Blackbomber said!!!! I would check the code and see if its the same cylinder misfiring and if it is then you should check sparkplug and see if its a bluish greenish stain on it, I also had the same problem on my 03 and it turns out the my exhaust valve were bent and it caused something to split and leak coolant into my cylinder. Good luck!

 

Ok, thanks.

Blackbomer: I also have a dodge ram 5.9, and it idles bad. When stopped on a hill it will stall, but I read that if you drop the oil pan their is a hose that connects to the oil pump that pops off, and is a common issue. I just haven't had time to do it cause I have been working on my car, and need 1 working vehicle. The oil light always comes on, on the truck before it stalls, and on the highway it backfires like crazy. I have time to work on it now, but don't have much money to live off of. Work isn't steady right now.

 

Like said above, have a compression check done...
the person doi g it may do it 2 times, one dry, one wet, meaning with a bit of oil added..

That info and a good mechanic listening for where the air leaks will give tou good info...during the compression check, the plugs can be double checked....they were likely run very hot during the overheating and may have cracked an insulator....

 

Ok, thanks everybody for the help, and have a happy new year.

 

Sort of off topic, but still your vehicle: I doubt a loss of compression would cause backfiring on the highway. What year is your truck? There was a TSB in '98, I think, about cross talk between the ignition wires, because they weren't routed properly. Even if your truck is newer, it's possible they are misrouted. Mine is a 2001 2500, and it was done the old way. Here is a link to the TSB http://dodgeram.info/tsb/1998/18-48-98/18-48-98-v8.htm

To check your plenum gasket on the Magnum, if you don't already know, just look down your throttle body with a flashlight, and see if any oil is pooled up in there. If there is, it's either a faulty PCV valve, or a leaking plenum gasket. In my case, I could see the oil pooling right near the cylinder #7 runner (one giving the code), so it was kind of obvious.

It sounds like you suspect the pickup tube fell out of the oil pump. If that is the case, then you are sucking oil from the top of the pan, instead of the bottom, and it will probably run dry every time you accelerate, turn, stop, and if the oil level drops even a bit. Not a good scenario. Fortunately, the oil pan is pretty easy to drop in place, at least on the 4wd models (I never worked on a 2wd, but I imagine it's also easy).

These engines are pretty forgiving, so it's very likely you have multiple issues. When cared for, though, they give good service. Mine is at 166k, and except for the rough idle from the plenum leak, it runs like a top. And mine wasn't exactly cared for. When I first got it, there was no heat. The issue was that the coolant had never been changed, and the heater core became plugged up. Did an old fashioned flush, and now I have heat. So if the PO didn't even care for the cooling system, imagine the rest of the truck! Yet it runs and drives pretty much like new.

 

I replaced the spark plugs in the mini even knowing they looked fine. I get 5 codes when I checked the computer.

P0300 random/multiple misfire
p0313 misfire detected low fuel level
p0500 vehicle speed sensor a malfunction
p1787 transmission limp mode EP is not displayed under speedometer though
p1698 no ccd signal recieved from tranny control module

Never mind, all the codes cleared out after I rigged up my air intake. Found another leak, and rigged it all up, but do want to buy a new air intake.

 

I saw clips missing to hold my air intake together. Why wouldn't this work:

http://www.amazon.com/Weapon-Secret-...5605636&sr=8-1

I know its for a cooper S, but why wouldn't it work for a base cooper? I am looking at that or a stage 2, but they are both for the cooper S.

 

I STRONGLY RECCOMEND fixing your orgional issue before modding the car and adding more varibles to the mix...

 

Not sure, not kinda $$ for a hai...
hai is a hot air intake....takes in hot/warm air from inder the hood...
a cai, cold air intake gets cold air from the outside...usually from ducting or removing parts of the plactic rear shield by the firewall...a sheet metal piece is usually added to keep the hot air away from the intake...
cai/hai have neen inexpensive diy items for years...or you can get a better engineered one that looks better for a few bucks...but $250 for an intake you have to chop up to try to make it fit...lol.
if you are gonna spend big bucks, get one that fits. Waymotorworks has a few gen one cooper intakes i think...
That and never underestimate what can be done with pvc, and the proper universsl style k&n filter....the orgional budget mod. Should be a bunch of threads around...

 

Everything is fixed. Drives better then ever. Faster then when I bought it. Should've replaced that crank pulley sooner cause that is some good horsepower gain right there.

 

I changed my wires, my coil pack, my plugs, no luck, no change.

I put injector cleaner in the gas when full, and again when the gas was low, nothing.

I was going to try the camshaft position sensor at $100, but

I changed my serpintine belt instead, and like magic, never saw the 300

code again.