Idle Problems

[klayvon]

Hey guys, I've got some idle troubles on my 86 325es. The idle likes to hang around 1300 rpm or so after I come to a stop light/sign or if I'm in traffic. I've checked all of the commonly known culprits, including the Idle Control Valve, the Idle Control, fuel pressure regulator, Oxygen Sensor (which was bad and I replaced), did a smoke test by running smoke through the intake manifold, and found no vacuum leaks, and checked the throttle body for potential damage. I'm wondering if any of you may know something I don't. I also had my muffler checked to insure that I am getting enough back pressure. I've been told that sometimes with after market mufflers, there can be a decrease in back pressure, causing the car to idle improperly. Let me know if you know of something that I may have overlooked here. Your help will be greatly appreciated. Thanks a lot.

[klayvon]

Oh yeah, I also check the throttle position switch and I changed out the cold start valve, thermostat and the temperature sender.

[jlevie]

Does the idle drop to about 900rpm if you disconnect the ICV? If not I'd suspect a mis-adjusted or sticking throttle body. If the idle remains high adjust the throttle stop and TPS will need to be adjusted. The procedure is in the Bentley. If the problem persists the ICV or idle control module is bad.

[klayvon]

I'm actually thinking its my DME after talking to several people. I've taken care of every common problem that can cause an idle problem. I'll be swapping out the DME this weekend. Thanks a lot for the help though.

[EtaSport]

the eta has an Idle control module as well. let me guess, when the car is cold it will idle perfect, then after it warms up and is driven it will idle really high. i also bet if you pinch off the hose coming from the ICV it will idle normally. however, it will idle like shit when cold if you do this. I found the best solution to this problem is to throw motronic 1.0 in the dumpster and get the fuel injection from a 325i

[klayvon]

It has nothing to do with the idle control valve or unit, its not the fuel pressure regulator, O2 sensor, throttle body, air flow meter, thermostat, fuel injectors, temperature sender, cold start valve, or fuel injection temp sensor. When i rev it at idle, the needle comes back all the way down to about 750 rpm and then it climbs back up to around 1300-1500. I suspect something is leaking somewhere and I am pretty sure there isn't a vacuum leak since I did a smoke test a few weeks ago and found no leaks. Something has to be leaking somewhere. I even tried swapping out a different ECU, no changes. I'm pretty much puzzled and at this point I'm going to start at my gas tank and check everything that goes from anywhere in that general area to the engine bay. Hopefully this way I can figure this problem out once and for all. I just know the idle is messed up and the car is running rich right now.

[scabzzzz]

Id suggest you listen to jlevie mister.

[EtaSport]

try unhooking the a/c switch input plug near the dme. purple wires with a black connector.