633CS Idle Problems

[slyhog-2201956]

I recently purchased a 1984 633CS and am having a terrible time tryint to get the 3.2 to idle smoothly at anything below 1500 rpm. The local BMW dealers cant offer any advice since service manuals are almost totally inexistant. Would appreciate any assistance with this problem and any assistance with finding service manuals

[njtech]

Sly,
any number of things can make the engine run rough. what service has been performed on the car? Start with the basics, check the condition of the spark plugs, wires, cap, rotor, make sure the intake boot is secure, check the valve adjustment, check for vacume leaks. check the idle slide valve as these are known to bind, clean it with brakeclean and spray a little WD40 in it and shake it up. These checks should help get you to the cause of the problem. HTH

[slyhog-22056]

I have tried everything I can think of...new plugs Bosch (wr9ls), new wires, cleaned and lubed the throttle plates and air box, back pressure check, even tried swapping injectors, vacuum leaks, I have 2 hoses that are leading from the bottom of the intake, 1 goes to the fuel pressure relief and the other one is plugged off, it is a 3/16 id hose and I cant find any place for it to run too. Finding info on this year and model is very frustrating, to say the least. Even after installing the new plugs it got worse, went from 22 MPG to a little over 16 MPG
?????????????????? HELP!!!!!!!!!!!!!!!!!!

[heywood_jablomi88]

Inorder to adjust the idle and mixture in most BMW's a special tool is needed, called a CO meter. All BMW dealerships have one, if your car has a motronic control unit (computer) the idle speed cannot be adjusted.

[heywood_jablomi88]

NOTE: If the idle speed is incorrec, either the idle valve or the idle control unit must be replaced.

[1983_633_CSi]

Brief suggestion -

I have a 1983 633. My engine idles rough from time to time. I have not taken it to a mechanic yet, but I've done a bit of research. Apparently, BMW did a recall on the 633 for a "rough idle." I'm not sure if any dealer will honor a 15+ year old recall.

If you run a google search on "rough idle, 1983, 633, BMW" you might find the same info I did. I realize this does not answer your question - just trying to inform your diagnosis.