[morecowbell]

2003 wagon, auto, 178k mi. original suspension.

Two symptoms, possibly related...first is a slight revving of the engine during normal cruising speeds, @100-200pm. Not constant, but getting more frequent, about every 40-60 seconds the engine will rev up suddenly with no increase in road speed. Not noticed at highway speeds( 65-75mph), mostly 40-60mph. Annoying, but not as troubling as the next problem.
Second symptom is a moderate shutter felt through the pedals and wheel. Feels like a going over a rumble strip, but without the tire noise. This has just started showing up in the last week, I can make this go away by giving the engine some throttle and it will downshift and accelerate normally. Then the shutter will disappear. I need this car to commute to work, am I screwing it up by driving until payday? Any ideas?

 

[Purple dye]

This is more of a general automatic checklist but did you check the fluid level? Have you changed the filter lately? It sounds like you have clutch discs slipping and they will be damaged if you continue slipping them. When it downshifts the stress on them for the same road speed is less because of the gear reduction.
When you have the dipstick out smell it and check for a burned smell.

 

[chittychittybangbang]

Unfortunately, there is no dipstick. You have to remove the drain plug with the engine running and warmed up. If a few drops of fluid come out of the drain hole level is good. If none comes out level is low. The fill cap is also easily damaged so it's best to buy a new one each time you fill up the ATF. Look through the "how tos" for a description of how to refill the ATF.

The 98-2003 TDI aren't known for robust automatic transmissions but before getting worried I'd check for any sensor problems like throttle sensors,etc. If it really is a bad transmission the general consensus is to get a rebuilt unit which should last a long time vs. buying a used unit which may have an unknown lifespan.

Do a full code scan and see if there are any other problems that could be causing a transmission problem. It definitely sounds like a transmission or sensor problem vs. engine problem.

 

[Purple dye]

Thanks for making me fell old Chitty. I guess i won't mention to check the kickdown cable that goes from the tranny to the carb.

 

[Therion]

Did you check for any codes? FWIH a bad transmission normally starts out as 1st or reverse problems.

 

[morecowbell]

Codes?

I ran a code check on every system. No transmission codes, only engine code was my friend the #3 glowplug, and the most likely suspect...front left speaker code!
I've been reading about other possiblilities, would a clogged intake mimic some of these symptoms?
Thanks for the replies! Tom

 

[chittychittybangbang]

It's possible that it could cause strange running. Take off the intake hose and take a look into the intake.

But I don't think it would cause revving for no reason.

 

[morecowbell]

update

transmission flush and service completed today. Road test indicates improvement, and disappearance of the shuttering problem. Fingers crossed for the time being...