First BMW, having two issues

[CornhuskE46]

Hello, I am the new owner of a 2003 335XI! I traded my gf for my 09 Jeep bc this car is.. eh, problematic?

So I have a couple questions about an issue or two I'm having,

1.) since I've driven with the car, whenever you go to take off in drive while the engine is cold it doesn't go. I don't know how else to explain this other then the rpms will bounce until you let off the gas and then re press a time or two. I saw a generalized post on some website about this and I was thinking about changing the trans fluid but I wanted to know if anyone had previous run ins on this.

2.) we had an issue where the BMW techs didn't leak the air out of the wet system thermostat and was overheating. But now, I went to check the coolant and it's all the way to the bottom low again. Is there any reason the car would be using coolant or do you think it's leaking?

I don't know if any of this is dumbass stuff and I'm def a wanna be Motörhead, I love cars but don't know too much of the mechanical jist of things yet. Any helps appreciated.

I also have very little knowledge of being in a forum so if I did this wrong please tell me lol.

[CornhuskE46]

I also just saw that the mileage is helpful, about 194k on the clock, yes. Old as hell and whoever owned it before her didn't do the best to take care of it

[dworthy]

Welcome to the Forum!

Okay, so BMW never built a 335XI in 2003, but they did build a 325IX and a 330IX, devil in the details here. So I will assume​ that you have a 2003, and not a 2007 or later 335XI.

If we are talking about a E-46 sedan with the M-54 motor, then the only good way to properly drain and fill is using a vacuum system. Can you do it the old fashion way? Sure, but why? As you now have first hand knowledge, it just doesn't work right.

As for the delay, again E-46 here, a fluid and filter change will help.

Lastly if you RPM bounces up/down that is indicative of a vacuum leak. If that shop is spraying flammables around the engine bay to find a small leak, find another place, for a smoke test is the only way to find a vacuum leak.

[MarcoZandrini]

The first step in diagnosing a problem is to scan the engine computer (DME) and the transmission computer (EGS) for codes. The EGS software may need to be updated to take care of the acceleration when cold issue.

Be advised that BMW sourced automatic transmissions from GM of France and ZF of Germany. They are different transmissions and require different fluids. How to tell? The fluid pan in the GM transmission has smooth sides. The ZF fluid pan is ribbed.