Evening all

I've just returned from a 550 mile round trip with 4 up and a boot full of stuff in my PD130 Passat.

I noticed something which I haven't noticed before, and I have a theory...

Basically, if I'm set on cruise to say 65mph, and I increase the speed to 70mph by pressing and holding the '+' button on the cruise stalk, I get a jerk when I release it.

This didn't happen with my 1.8T Octavia and I hadn't noticed in the Passat until today... Athough I haven't used cruise much before. I don't think this is how it's supposed to be, it basically makes increasing the speed a 'foot only' job unless I want to irritate my passengers.

I also don't believe that the vibration I get at 1800ish RPM is just 'how they are', I'm convinced my car has an underlying issue. I don't doubt what people have said about them being a bit rough and ready, but I think mine is broken.

Now, my theory is that the DMF is broken, and the jerk is caused when the 'slack' in the DMF is released as the load on the transmission is released.

Another symptom I've noticed is that every now and then (and it is fairly rare) I go to pull away in first gear and the clutch bites very suddenly and I stall... I know this sounds like I can't drive, and it is a possibility, but im not convinced.

Oh and I have a slight whine in 5th and 6th gear but I think that's an unrelated (dying gearbox) problem.

Any thoughts on my theory, or other ideas would be grateful. I think it's getting to the point where I need to take it to be looked at, but I'm very busy at the moment.

Thanks in advance.

P.S. Sorry for multiple posts, I'm not sure if the 'faults' I am experiencing are independent of one another or all symptoms of the same problem.

If you use the "speed up" mode on your cruise control when the vehicle is either heavily loaded or going uphill (same thing as far as an accelerating engine is concerned) you are demanding a lot of extra torque to make this happen. Consequently, when you "switch off" the extra torque demand by releasing the top of the cruise toggle, there will be a jerk when this comes off.

Although I like the cruise facility and it works well, I don't use the "speed up/down" facility for this reason. To speed up, just feather the speed to the new value with the accelerator pedal and store the new value. To slow down, just knock it out of cruise with the slider switch (or pedals if you must), let the vehicle slow under its own losses, then re-engage cruise at the new speed.

This method is far kinder to the drive train (esp. DMF) and to the occupants than the "+/-" facility. I soon learned this when towing where you need huge dollops of torque to get past anything - which it will do.

It does sound as though, from the symptoms you describe, that the DMF is on its way out. Maybe live with it until the transmission meets its maker...

rotodiesel.

It does sound as though, from the symptoms you describe, that the DMF is on its way out. Maybe live with it until the transmission meets its maker...

Yeah, I think that's fair - but surely a new 6-spd and a DMF would cost a fortune?

I do agree with the torque option - it had nowhere near as much torque but the cruise on one of my previous vehicles still "bumped" when it stopped accelerating. It was annoying.

BTW Roto, I thought you were a fellow poverty-spec reveller? What's all this about cruise control? :eek:

I've just returned from a 550 mile round trip with 4 up and a boot full of stuff in my PD130 Passat.

Glad the trip went well

Thanks for your comments.

It's nice to hear the cruise jerk doesn't appear to be anything too serious.

I just started it up today and it was very rough, shaking and rocking quite badly :( I turned it back off and scanned it with vag com which showed no faults. I then started it again and it was better but not normal, so I gave it a quick rev up to about 2k RPM and it seems to be ok again now...

Poverty spec Superb - but that didn't stop a bit of bargaining at the time of purchase. Cruise is the only useful extra the base model doesn't have but is a cheap retrofit as it's all in there, apart from the column switch and a software enable - real cost about £20.

When buying a lemon such as a Superb, screw the dealer for anything worth having - these cars are nearly impossible to shift. I got exactly what I wanted to do my job but I'm under no illusions as to what it's now worth.

rotodiesel.

Poverty spec Superb - but that didn't stop a bit of bargaining at the time of purchase. Cruise is the only useful extra the base model doesn't have but is a cheap retrofit as it's all in there, apart from the column switch and a software enable - real cost about £20.

When buying a lemon such as a Superb, screw the dealer for anything worth having - these cars are nearly impossible to shift. I got exactly what I wanted to do my job but I'm under no illusions as to what it's now worth.

rotodiesel.

yawn