jumping rpms

hi......does anyone know why my RPMS are "jumping",when the car is idling????.....

(disclaimer:I'm not familiar with BMW engines, but do a little motor work on other cars.)

This is called idle surge... There's a few reasons this could happen, first I'd check your spark plugs, if they're cruddy or gapped wrong, they can make the car miss...

also, make sure you have no holes in your intake hoses, if so air can come in and make the car meter the air wrong...

is it just doing this when idling? only when cold/hot? any other problems just show up? how long has it been doing it? any recent changes to the car?

(disclaimer:I'm not familiar with BMW engines, but do a little motor work on other cars.)

This is called idle surge... There's a few reasons this could happen, first I'd check your spark plugs, if they're cruddy or gapped wrong, they can make the car miss...

also, make sure you have no holes in your intake hoses, if so air can come in and make the car meter the air wrong...

is it just doing this when idling? only when cold/hot? any other problems just show up? how long has it been doing it? any recent changes to the car?

actually it never heppens when the car is cold,only on traffic lights(when its already warm). its not like its always doing it....some days it does some it doesnt...no recent changes, and yes,there was a problem like 5 days ago(on my way home,"service engine soon" light went on,i got home shut down the car, and when i started it the next day it was off already.

actually it never heppens when the car is cold,only on traffic lights(when its already warm). its not like its always doing it....some days it does some it doesnt...no recent changes, and yes,there was a problem like 5 days ago(on my way home,"service engine soon" light went on,i got home shut down the car, and when i started it the next day it was off already.

I suggest taking the car somewhere and getting them to scan it with a diagnostic tool... you might have to find someone with one that's a little more expensive than the handheld units, but it should be able to pull up stored codes in the ECU... that will most likely give you an idea or starting point...

if you get that code, post it here... the code and the description if possible, if not, the code will do... and I might can point you in the right direction... the codes are usually generic, but there are a few things in each system (fuel, ignition, exhaust, etc..) to check...

Also, I'm trying to blindly diagnose this problem, could you give me the make model and year etc on the car... mileage too (might be helpful if it's just a tune up issue, certain parts can go bad after X miles)...

I suggest taking the car somewhere and getting them to scan it with a diagnostic tool... you might have to find someone with one that's a little more expensive than the handheld units, but it should be able to pull up stored codes in the ECU... that will most likely give you an idea or starting point...

if you get that code, post it here... the code and the description if possible, if not, the code will do... and I might can point you in the right direction... the codes are usually generic, but there are a few things in each system (fuel, ignition, exhaust, etc..) to check...

Also, I'm trying to blindly diagnose this problem, could you give me the make model and year etc on the car... mileage too (might be helpful if it's just a tune up issue, certain parts can go bad after X miles)...


its a 2000 bmw 323i, 160,000 km
u said it might be because of bad spark plugs,I`ll try to change them first,cuz i havn`t since I bought this car (a year ago with 126,000 km on it).
I looked under the hood but couldn`t find them,cuz everything is covered with plastic(ARE THEY UNDER IT?)

ok, I realize this isn't the engine you have (yours will be an E52, if I'm correct, and this is for an E46), but it is similar...
http://www.data.bmrparts.com/qimages/A388119_810471_1.jpg


^Right up there on the top of the motor, there is usually a black cover... I think it says BMW or something (it may not)... it should have two screws or nuts holding it down... you simply remove that cover and the spark plugs and wires should be sitting beneath that cover...

With you putting that many miles/kms on the car, I'm going to assume that's the problem... it's most likely miss firing every now and then...

Edit: Looking at this pic, the left side will be at the back of the engine compartment, you will actually be looking at it from the other side... but the cover will still be on top of the motor...

Hello,

I've had the same problem with my 2001 325i since "day one". It only happens every once in a while at a stop light. Sometimes the car idle will drop below normal for a second, and it seems like the ECU attempts to correct by increasing the idle. The result is an idle that bounces between 400 and 1000 RPM. The problem usually corrects itself after 4 or 5 seconds, and then wont reappear for weeks. I've had BMW look into it while it was under warranty, and they were not able to find anything wrong. I've looked the car over many times since I've owned it. Through the years, I've had to replace several sensors (crankshaft speed sensor, camshaft position sensor) which while fixing their particular problem, have had no affect on my Idle surge problem. Since then, I've chalked it up to a design flaw in how the ECU manages the idle under certain engine conditions. Let me know if this sounds like your problem, and if so, if a fix worked.

Anthony

ok, I realize this isn't the engine you have (yours will be an E52, if I'm correct, and this is for an E46), but it is similar...
http://www.data.bmrparts.com/qimages/A388119_810471_1.jpg


^Right up there on the top of the motor, there is usually a black cover... I think it says BMW or something (it may not)... it should have two screws or nuts holding it down... you simply remove that cover and the spark plugs and wires should be sitting beneath that cover...

With you putting that many miles/kms on the car, I'm going to assume that's the problem... it's most likely miss firing every now and then...

Edit: Looking at this pic, the left side will be at the back of the engine compartment, you will actually be looking at it from the other side... but the cover will still be on top of the motor...

i`ll try to replace them this weekend.
p.s: as far as I know 2000 323i`s some with E46 engines(2.5 liter inline 6, 170HP)

i`ll try to replace them this weekend.
p.s: as far as I know 2000 323i`s some with E46 engines(2.5 liter inline 6, 170HP)

sry, I only skimmed over the wikipedia, then went looking for motor pics...

GL and let me know what happens...

hey!
today i bought 6 spark plugs,but after removing the plastic cover I was not sure where they should go! the engine is covered with 2 pieces of plastic(first of all I dont know if the part I took off was the right one-I took off the left side).....there were 6 THINGS (things cuz I dont know what they were)....but if there were 6 I figured that they must have been the spark plugs(there was 2 screws on each) after I loosened them and pulled them out there was something looking like a rubber hose going down into the engine block......soooo.....were those the spark plugs or not........because I dont really want to mess anything up.....
thanks alot

can you take a picture?

I believe that you are describing something like a coil on plug system (not sure that these motors run them)... what that is, is the motor will have individual coil packs for each spark plug...

Actually, here's a tuneup write-up for the E-36... your's will be a little different, but this will be pretty close...
http://www.pelicanparts.com/bmw/techarticles/E36-Spark-Plugs/E36-Spark-Plugs.htm

I was just looking around the internet and found out that there was a technical service bulletin for an erratic idle with possible stalling. Reference service measure #B12-207-0 with your dealer.

I don't know the details of the service bulletin yet.

I found this reference (with other useful information) at this link:

http://www.bimmerfest.com/wiki/index.php?title=BMW_E46#What_is_an_E46.3F

Anthony

thanks for your help ppl....changing them was very easy.