Rough idle, harsh down shift when stopping

[Jordo]

What's going on guys? It's been a while since I've been on here. My wife's POS Kia died, and as the cookie crumbled she took over my 02 X5 as her daily driver.

About 2 months ago 2 deer jumped out in front of her on her way to work. She took 1 out... But it took out the 'ol X5. It was a great ride and I'll miss it for sure.

My wife liked the X5 but thought it was a bit big for her. So after we got insurance money we went out to get an X3. We got a 2006 X3 with 98k on the clock. We like it, we test drove other make and models but none drove like an X3.

Now that said, this X3 has a rough idle when in park. It idles fine when in drive (but stopped). The dome light dims in sync with the rough idle. Any other part of the RPM (above idle) no issues. It runs as intended.

The 2nd and last issue is when slowing down to a stop... It clunks just before it's stopped. It seems to me it's a tranny issue. But I could be wrong. I should add this happens when slowly slowing down. If I come to a more agressive stop there is no clunk. So I'm stumped.

I'm getting no warning or error lights in dash. No check engine or fail safe like I had in my X5 when the torque converter was shitting the bed.


Any help would be greatly appreciated.

[Jordo]

Could it be from a bad battery? When starting the X3 it cranks a little slow IMO.

[JCL]

It could be just about anything.

Rough idle could be vacuum leak, fuel, electrical, emissions controls, you name it. When the idle goes very low the alternator isn't charging as much and you see the lights dim.

Yes, the battery could be failing. Particularly if it is the original battery, you would be on borrowed time.

There were complaints of the transmission clunking when the vehicle was new, various X3 models. Not sure if there ever was a software update or not.

[Jordo]

Thanks JCL.
Does the fact that it's idles rough in Park but smooth in Drive, help diagnose it at all?

[JCL]

I would be looking for vacuum leaks, around the intake boot or CCV. Any codes?

[Jordo]

Nothing indicating that on the dash... But I do have a OBDII scanner. Should I plug it in anyway?

[JCL]

I'd try it. If it doesn't show anything useful, get the codes read by a device that knows the BMW engine codes.

[Jordo]

JCL, your good man! Looks like it's probably an air leak....

[Jordo]

Oh... Forgot to ask... Any help finding the location of the CCV ?

Thanks :-)

[AzNMpower32]

The CCV is a pain in the arse to access, located at the backend of the engine compartment in front of the driver/firewall. You will have to disassemble practically everything on that half of the engine bay to get to it (took the indy shop 5h of labour). Setup is nearly identical to that in the E46; don't forget to replace the hoses as well.

However, a variety of other things could cause those lean codes: intake boot leak, DISA valve, CCV, possibly other items.