'02 BMW 325i Problem Question - United Bimmer Community

**JGreene** · 07-08-2009, 12:16 AM

I was wondering if any of you had run into this same problem with you BMW's. Mine is a 2002 BMW 325i. Basically what it is doing is, when I maintain a steady speed below say 50 or so, whether in cruise or not, it drives normal but then if you watch the tachometer, it rhythmically drops about 400 to 500 rpms all of a sudden and jumps back up real quick, and keeps doing that over and over again really close together until I rev the engine or change speeds. You can also hear the engine rev lowering and raising with the tachometer, so it isn't an instrumental malfunction I would imagine. If anyone has any clue what is happening and what needs to be done, please let me know.

**HyeTide** · 07-08-2009, 03:02 PM

Could be an transmission problem? Same thing happened to wife's car. Tach would move 3 to 4 hundred rpm while driving steady. Trans died soon after but was replaced and covered by stealership.

**JGreene** · 07-08-2009, 04:39 PM

Quote:

Originally Posted by HyeTide

Could be an transmission problem? Same thing happened to wife's car. Tach would move 3 to 4 hundred rpm while driving steady. Trans died soon after but was replaced and covered by stealership.

How soon after did it die? Mine has done it for about two months now. Do you have an idea about how much it cost to replace the Transmission?

**HyeTide** · 07-08-2009, 07:44 PM

Quote:

Originally Posted by JGreene

How soon after did it die? Mine has done it for about two months now. Do you have an idea about how much it cost to replace the Transmission?

It started to buck and shake soon after, maybe a month or so. Don't know how much it cost , dealer put new one in under warranty . If I had to pay for it I would take it to a trans. shop. GL

Big Evil · 07-09-2009, 12:50 PM

Sounds like the Torque Converter Lock up (TCC) engaging and disengaging. That can be caused by a bad/intermittant read from the TPS or a faulty solenoid in the tranny. Throttle position sensor would be where I'd start looking first, I've seen tranny replacements done 3-4 times on the same car and it didn't fix that, but replacing a single sensor not even in the tranny did. Maybe this helps.

**JGreene** · 07-09-2009, 07:43 PM

Quote:

Originally Posted by Big Evil

Sounds like the Torque Converter Lock up (TCC) engaging and disengaging. That can be caused by a bad/intermittant read from the TPS or a faulty solenoid in the tranny. Throttle position sensor would be where I'd start looking first, I've seen tranny replacements done 3-4 times on the same car and it didn't fix that, but replacing a single sensor not even in the tranny did. Maybe this helps.

Thanks, I am assuming that replacing a sensor would be cheaper than the Transmission. If so then this sounds great, I'll try to start with the Throttle Position Sensor then.

**JGreene** · 07-09-2009, 08:07 PM

Would the Throttle Position Sensor on my 2002 BMW 325i Sedan, be called a Camshaft Position Sensor or a Crank Position Sensor? I cannot find anything on a 2002 BMW like mine called a Throttle Position Sensor when I look it up online, only for earlier models.

Big Evil · 07-10-2009, 10:26 AM

It's called the TPS the other 2 are for the cam and crank. I went and looked at egerman and autohausaz, bav didn't have anything. From the picture though, it looks like the tps is integral to the throttle body (meaning built in and not serviceable separately). May be worth your time to take it and get it scanned for faults before you tear to far into it, beemer specific shop or dealer, not general independant shop.