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Discussion Starter #1
I have searched and read as many threads as possible and haven't seen anything that quite details what my car is doing, so I hope someone on here may be able to pinpoint it or at least point me in the right direction.
On my 2001 325 xi wagon, I have idle issues no matter what temperature it is outside or if the engine is up to normal operating temperature or not. The RPMs bounce from 450 or 500 up to about 800 to 1000 for about a minute or two and then will finally settle at about 650 or so. It does this every single day. I use premium fuel all the time, and have even tried an octane booster (because 90 octane is about all we have here) to bring the octane up even more to see if it would do anything. It also has no starting issues, no hesitation and it cranks smooth and quick. It doesn't appear to be fuel or fuel pump related (I'm going to check and possibly replace the pump and filter anyway, just to be sure). I know I need to check the IAC, Vanos, Crankshaft sensors, and maybe the DISA. I'm not getting any codes or CELs, so I'm freaking out trying to think and decide what to check. I really don't want to just start throwing new parts in there hoping to fix the problem. If I can, I will post a video of what it is doing, if that will help.
 

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17-18 year old car that has probably all original parts still installed other than oil, oil filter, air filter and brakes!! Nothing new around here.

Just because there is no SES/CEL/MIL does not mean anything, there can and will be all sorts of problems that never trigger lights or codes.

Most of the rubber under the hood needs to be replaced at this point. You might as well commit to it because to even clean the ICV you need to remove the intake boots.

Suggest you read this thread if you have not seen it: Solve your misfires, lean codes, rough idle - https://forum.e46fanatics.com/showthread.php?t=897616

You also need your own OBDII tool.

If you have a smart phone or tablet, get an OBDII App and interface so you can read the codes along with Live/Realtime or Freeze Frame data then you will know exactly what is going on with the engine fuel management system.

The OBDFusion App and proper VeePeak interface from Amazon are less than $40 for both for iProducts, less than $20 for both for Android.

OBDFusion for Android is $4.99 from the Google Play Store.

For Android this lower cost standard Bluetooth interface in the link below works well, but DO NOT try to use this with iProducts.

https://www.amazon.com/Veepeak-Bluetooth-Scanner-Automotive-Diagnostic/dp/B011NSX27A/ref=sr_1_1?ie=UTF8&qid=1487373393&sr=8-1&keywords=veepeak+bluetooth

OBDFusion, for the iProducts it is $9.99 from the Apple App Store.

For iProducts you NEED a LE Bluetooth adapter which are more expensive. VeePeak now offers a LE Bluetooth interface that is compatible with OBDFusion in the link below. While people have used the Wifi adapter, I would HIGHLY recommend NOT using Wifi with iProducts, brings a lot of baggage and stability issues.

https://www.amazon.com/Veepeak-OBDCheck-Bluetooth-Diagnostic-Supports/dp/B073XKQQQW/ref=sr_1_2?ie=UTF8&qid=1504549087&sr=8-2&keywords=veepeak

Suggest you also read the PDF in this thread for more details about how to capture and share the data - http://forum.e46fanatics.com/showthread.php?t=1097893 This info is Android specific, iProducts is similar, menu options may be different.
 

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Car needs full restoration as I've said years ago, for years. Idle bouncing can be caused by a vacuum leak or idle control valve being dirty or needing replacement.

The idle going up is the car correcting a detected low idle and trying to dump fuel to correct it. Then it detects the idle being too high and cuts fuel. The correction cycle repeats itself resulting in a bounce.

So you have to figure out what is causing the deficiencies. Too much air going in (a leak) or a mechanical fault (a valve sticking)
 

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Discussion Starter #6
Okay, so quick update.

I ended up having to replace ICV, DISA, Coils and plugs, and I had a small leak in my intake. I also took the route of replacing all hoses and anything that looked old (tax refund came in handy). Car runs much better now and no more idle jumping. Thanks guys!
 

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So, another quick update:

After replacing all of the above stuff, the idle bouncing came back. I further diagnosed the issue after reading a bit more and taking the upper engine apart...completely. I discovered a leak coming from my valve cover. So, I went about replacing the valve cover gasket and spark plug well gaskets. The gasket was blown out on the back side (not huge, but definitely enough to make the car act strangely) and one of the spark plug well gaskets had actually partially melted. Replaced all gaskets and even added the RTV silicone gasket maker around the VANOS and the back side where the old gasket failed. While I had the engine apart, I went ahead and replaced a bunch of hoses. I may have missed a couple, but I'm pretty sure I got 98% of them that I could reach. Obviously the Secondary Air Pump vacuum line was brittle and was replaced. It has been over a week and the idle issue hasn't come back. I'm getting better gas mileage and performance is much better.
 

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OP, if a shop told you you needed all that stuff, I think you should find another shop. That leak would have been easily found by smoke testing. If it was you, I'd just say to slow down a little on diagnosing stuff or your car will get to get very expensive, very soon.

My icv is original...I just replaced disa since it was just beginning to lose its vacuum (at 370,000 miles). Coils can also last almost forever...but many replace all of them when one goes bad...just coz.

Anyway, just be careful tossing parts at the car hoping one will stick...and check out your regional forum for a well recommended local shop for you to have as a backup.
 
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