Shudder @ 1750 RPM

I've got a 2003 Jetta TDI Wagon. And it has a strange shudder that you can feel in the steering wheel, and whole car really. It happens under very predictable and narrow range of conditions and I'm trying to figure out what system it is coming from... engine, suspension, turbo?

It generally occurs right around 1750-1850 RPM when slightly under load - such as going up a slight hill or accelerating on a flat. When it occurs one can feel it all over, its a pretty substantial shudder. When it happens I let off the gas and it immediately goes away (all within a second or so) then I continue driving.

Seems to happen more when the AC is on - possibly due to the extra load the AC puts on the engine.

My initial thought was that it was in the suspension, but the narrow RPM band and responsiveness to letting off the accelerator would suggest that it is in the engine.

Any ideas? What should I check?

Auto or 5 speed

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Good question - Auto

its definitely the transmission.

ok, how do I trouble shoot the trans? Is there some thing that I try replacing the fluid or changing some sensors, or just wait for it to get worse and replace it with a manual?

its been in it's current condition for a while and doesn't seem to be getting worse.

In the dumb stuff category, check if one of the wheel weights has fallen off.
Then I would try to rule out the transmission.

Convincent said:

ok, how do I trouble shoot the trans? Is there some thing that I try replacing the fluid or changing some sensors, or just wait for it to get worse and replace it with a manual? its been in it's current condition for a while and doesn't seem to be getting worse.

Click to expand...

Deep research, user CoolAirVW
might chime in, I've linked his website above.
User contributed search engine- VW TDI Search Engine

You may even want to try generic advanced searching, a lot of the stuff you'll find in the forum is iffy. Many don't post back solutions and some are just wrong.
As you get started, scan for stored codes and do a good visual on those suspension bits.

A trans service wouldn't hurt, just use the proper fluid, replace the pan gasket and get your level right and it might be gtg

How many miles on the transmission?

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ok I'll start with checking the wheels, and suspension.

The car has about 260k on it, I'm not the first owner so can only assume that the trans has that many too.

I'm having a similar problem right around 1800 rpm and again at 3800 rpm. Doesn't shutter as bad as yours, but it's a vibration I can feel in the steering wheel and gas pedal. I have a 5spd manual tho. It started right after I had the passenger side cv axle (the longer one) replaced. Doesn't matter what speed or gear, just at those 2 rpms. It feels like the engine is bolted directly to the frame transmitting vibration to the car, but smoothes out under and over that rpm.
I think it's because I went with an Autozone axle instead of the OE style which is probably more balanced and dampens vibration better.
Have you checked your CV's?