Engine speed blipping, tach goes dead, cruise drops out

Having a weird problem with my 2006 Jetta, 241k miles.

First thing I noticed was engine speed rising or falling 30 or 50 rpm or so for a second or less at a time. At first I only noticed it because my head would bob a little - very subtle. Either this only happens when I'm above 65mph, or I'm only noticing it then. Changed the fuel filter, symptom persisted.

Now I'm having episodes from time to time when the thing just loses its mind. The cruise control drops out, the wheel slip light comes on, the oil light comes on, and the alarm sounds. While this is going on, the tach needle falls to zero for a few seconds, comes back up to where it's supposed to be, falls, back and forth. Apart from the dash lights and alarm, everything seems fine while this is happening. That is, the car runs and drives okay.

During the most recent episode, a new development: an amber light came on in the tach and went out again so quickly I couldn't see what it was. I then almost immediately lost power and was unable to maintain speed for around three seconds before power returned and everything seemed fine except for the tach needle, slip light, and oil light.

Every time this has happened I can stop the car, restart and all is normal again.

The only thing the local guru shop could find wrong with it was a faulty camshaft position sensor, which they replaced. The car runs a lot better in general with the new sensor, but the engine speed blip thing persists. I expect to experience further cruise/tach/warning light episodes, but haven't had one yet since I got the car back with the new sensor.

Anybody had anything similar? Any ideas? Thanks.

Me 2

Hey I have this issue too. except my doesn't come back on by itself. Mines keep blowing a 5amp fuse and all the same systems go down till I replace it. Its been raining heavily here all week but tomorrow I'm gonna look for the short and I'll let you know more then. Meanwhile, check the wires in the engine bay, especially near the throttle body(ASV) for melted wiring or wires with cuts in them. Basically whats happening is the ECU is losing communication with the module that controls vehicle speed

Search the forum for posts by Oilhammer and others related to engine wiring harnesses, grounds, and mystery problem repairs.

The camshaft position sensor seems to have stopped the freakouts, but the engine speed blipping thing continues. I've noticed that the engine speed change is always the same - engine speed falls about 30-50rpm for about a second, then surges around 30 or 50rpm past where it's supposed to be for a split second, then settles back where it belongs. It's like the engine suddenly becomes bogged or restricted or something, realizes it, and does something to correct.
I'm also now getting limp mode sometimes. I found a pending P0299 (insufficient boost) fault with my OBD. I'm not getting any of the bad turbo symptoms like noises or smoking, so I suspect it's something like the vacuum lines, solenoid, or actuator problems I'm reading about in the limp mode threads.