Rough idle - yes I searched
 

As the title states I've read all that I could on the rough idle but still not 100% what im after. As you can guess my car has a rough idle but to an extent also continues as I drive. I can barely feel it as im driving. Almost like a slight shimmy or something. As I sit and idle its an in and out rough feel. Ny finace says she dosnt notice it but I do. The hotter it is outside the less it does it. This morning at around 70° it was slightly more noticable than this afternoon at around 90°. Just seems smoother as it gets hotter outside. Ive checked all hoses and replaced the plugs. Havnt gotten to the wires yet since im broke paying for my wedding. Ive pulled the PCV valve and cleaned it inside to where it was spotless. Still nothing has changed. Any ideas would be appreciated since I will be taken the 318 on my honeymoon and dont want to be stuck on the highway. Thanks in advance!!

EDIT: What im asking is that if you have had the exact same problem and replaced 1 certain sensor to solve it or made an adjustment please let me know. I hate to go and dish out a bunch of money and replace different things when all I needed was one item.

EDIT: Also, the previous owner was only runing 87 octane. I switched to mid grade and have only been useing Shell gasoline since all the others around here are garbage and stalls out other cars including my fiances. I put some seafoam in the gas in hopes of cleaning any injectors that might be clogged.

I'm no expert but I kinda had a rough idle issue too. Not as you describe but nonetheless, I check my spark plugs to find oil with every plug, after changing them, the idle was smooth as can be. Now, it starting to act up again because I haven't solved the issue (valve cover gasket). Plan on doing that this weekend.

Hope that helps a little!

LOL I was just reading about the oil on your plugs. My car is not leaking oil and when I changed the plugs the old ones were clean. They were worn but useable. I just make it a point that when I buy a used vehicle that I change all fluids, plugs, wires, ect. I just get real anal about how my cars run and this is driving me crazy. It should be smooth and purring like a kitten!! Thanks for the heads up though.

Vacume leaks.

Take the rubber air tube between the throttle body and the air flow meter off, and clean it, you'll likely find little cracks in the bellows, its like 29 bucks at the dealer and raises hell when it wears out.

Dave

That was one of the first things I checked and I did find some cracks. I used a rubber epoxy and sealed them up for the time being. Guess I should look at replacing. Thanks.

Anyone else? Ideas? New boot was not the issue.

There's a tiny vac hose that makes a 90 degree downwards comming out from a tube from the upper intake in the front. It's so small that perhaps you may be missing it ot it got unplugged.

Thanks ti. I will go and double check that!

check the hoses and check the belts, my belt went bad and it gave an impression of rough idling when it was just really a noise making me paranoid lol

Thanks for the response. Belts were checked first thing and its not a sound. Its an actual feel. I believe I might have found it. There is a hose running from the back of the upper manifold to the idle controle valve that is cracked. I didnt catch it on my first inspection since its hidden pretty good. Local BMW dealership says they will have the hose for me by Monday. Guess I will see if its the culprit once it arrives.

Just a heads up to those not in the know. Im sure all the verterans here have either delt with it or know about it. I found that one thing and it was a hose that runs from the back of the upper intake manifold directly underneath it to the idle controle valve. I have the M42 if your wondering. Takes less than an hour to replace if you know what your doing. Just remove one end of the hose that runs from the PCV valve, remove your intake boot then your upper intake manifold. Try not to lose or damage your IM gasket or just replace it while you are there. You dont have to disconnect everything from the IM. Just move it enough so that you can get under it. Be sure to put everything back and dont over torque your bolts. That simple.

see if this will work

http://forums.bimmerforums.com/forum...d.php?t=454501

Nice link. Thanks!

did mine ....

changed the two hoses connecting to the icv
changed the hose from the engine valve cover to pcv valve
sprayed the icv with throttle body cleaner and lightly brushed

engine does run smoother...

I already replaced the boot with a new one. All it ended up being was a hose running from the back of the upper IM running to the ICV. After I fixed that it was fine. I went back yesterday and pulled the ICV and cleaned per the suggestion above for good measure.