2005.5 BRM Jetta - Fluctuating RPMs

Ideas and Help are welcome on this.

I have a 2005.5 Jetta with the BRM engine.

For the past couple of months there has been a noticeable fluctuation in RPMs after the engine warms up and we are driving at HWY speeds. On a long drive I switched to the manual mode and dropped into 5th gear. The fluctuations stopped. Strange.

I also notices that the fluctuations, and kind of rough running, is only present in even gears (2,4,6).

My VW Mech. (via the phone) said this may not be anything you want to deal with until it gets bad. So I am reaching out to see if others have had this experience and have suggestions on remedies.

I worry it is the tranny. Maybe just a fluid level thing, or worse.

Thanks for any help folks can offer.

Personally if you don't have any codes, drive-ability issues or any other problems other than the tach needle fluctuating a touch I wouldn't worry about it.

* assuming your DSG has been serviced and isn't low on fluid. *

FWIW my speedometer needle will twitch ever so slightly when I'm cruising at a steady speed.

A dirty fuel filter will cause fluctuations in RPM's, as the engine is starved for fuel.

All, thanks for the ideas. I did change the fuel filter (and air filter). The RPM fluctuations are very regular (in the even gears) and noticeable in terms of the speed fluctuations.

Other ideas or folks that have experienced this or something similar.

Check your battery condition and electrical load. Alternator load will cause engine to gain rpm's. Otherwise ALL filters as this is the first rule of diesel.

Vacuum lines need to be checked as does the turbo actuator motor. The vacuum components MUST hold vacuum and a pin hole anywhere in the system can be cause for a problem such as described.

While you're chasing around it would be best to check the EGR cooler for a bad bushing and the associated exhaust leak. Further, double check the EGR valve at the top left side if the head and valve cover. If either the actuator or sensor is faulty, then you may be assured at some point that you'll regret not having done so.

If you have VAG-COM and you suspect a bad EGR valve, then disconnect the electrical connection and run the snot out of the car. You'll set a CEL but the car should run just fine. Remember that IF a bad valve, then it could be either the sensor side or the actuator itself. Replacement is quick and easy. DO NOT replace with anything but a OEM quality component from one of the vendors listed here.

Addendum... I forgot to mention the fuel pumps. You actually have two. I doubt this is the problem but you never know. Make 100% sure that the primary pump delivers fuel when the ignition switch is activated. Actually you probably have done so when you changed the fuel filter, but I needed to say it anyway.