318i idle and maf

[DangerRangerDan]

Hi everyone, Im hoping to get some info/suggestions before I do anything. I could probably manage this problem on my own, but since I already read a lot of threads on here and own a BMW, I might as well get involved in the community. So the main issue is this: I can start the car perfectly fine at normal idle rpm, but after driving and putting the car in park or neutral the rpms jump to 1500 sometimes 2000. They'll drop back down to normal range in any gear. And today my cel came on and I pulled two codes. P1140 Now I know this is generally attributed to a maf sensor or the wiring harness, or a vacuum leak. But ive rwad some threads where people practically changed almost every related part O2 sensors, icv, maf etc, and no change then their fuel pump quits and after replacing the code drops. And the other code is P0500 speed sensor which will probably need replaced. The trans shifts hard sometimes mostly from drive to R, and P. I did the math and my speedo is 109% of actual speed. This could be unrelated as ive been aware of the inaccuracy with no code for some time? Any thoughts or suggestions? Im broke so I dont wanna go replacing anything I dont need to.

[Eric93se]

If your broke then ghetto rig a smoke machine to test your vacuum system for leaks. Also if the vacuum hoses are old or original, it's just wise to replace them all, its cheap. Once you fix all the vacuum leaks, if your oxygen sensor is old then replace the pre-cat sensor.

[DarbBMW]

Check your main air intake, see if the hose underneath it came unplugged. This one is common to get pulled off when working on car and very hard to see. It is a big hose. I missed it on mine and caused weird issues and would not get smog readiness monitors to set.

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[MazerRackham]

Definitely sounds like bad MAF, vacuum leaks.