Luftkühl

LM964

Same effect when idling and stationary and through any rev range?

Brake fluid at Max line and not a millimeter below? May want to check/clean; wheel speed sensors, accelerometers, swap out DME relay (R41) - just to rule this crtical relay out, check/swap out ABS relay (R34). Others will chip in with more suggestions. I have 2 C4's and those two relays I carry as on board spares.

newsboy

Running voltage should be between 13.8 and 14.4 volts, so perhaps the alternator?

JohnK964

Goughary

First thing to look at when you have xmas tree is your coils. In all likelihood they are going.

It's very common. We have all switched to 993 coils cuz i got frustrated changing coils too often.

There are a couple good diy threads on rennlist and ours is somewhere in the suspension madness thread

wallra

to me it looks like not charging. should be at 14 volts

rsabeebe

man, i saw 'christmas tree' and 'jerking' and thought i better not open the thread!!

JohnK964

Gmyres

Luftkühl

A914MAN

When mine did that it was because the shop that worked on it right before I got the car had left a plug wire off. Drove home 725 miles no problem, 2 weeks after I got home I experienced the same trouble.

Luftkühl

Hello everybody
had very little time this weekend
@LM964: happens suddenly while driving, revving up is almost impossible because of the power loss due to the 'jerking' (have a look at the rev needle just above the multimeter in my film). I was lucky to be able to shoot this film at twilight, when there was little traffic and I was driving on a long stretch. When then car behaves like this, from the moment you let go the gaspedal (red light etc), the motor stalls. It is as if it has not enough momentum to keep running. At the end of the movie, even without letting go the gaspedal it stalled anyway.

The funny thing is that this comes up unexpectedly, now since three weeks.
I do think that my alternator is not loading correctly anymore, but the battery is brand new since one week and fully charged with a trickle charger (or what is the correct English term?). But its true: I think I will have to replace the alternator: ill make some footage when I swap the DME to show the charging voltage.
But I wonder if replacing the alternator will cure this strange behaviour since I did only a short ride with a fully loaded battery...

I am also intrigued by the fact that the voltage, as measured on the battery poles with the Fluke wireless display multimeter, stays exactly the same during when the car behaves odd?? Is there an explanation for this?

cheers from Belgium
Greg

Luftkühl

When I start changing the relais: does anyone know the cheaper VW part number for the R34 928-615-124-01 abs??
thx

JasonAndreas

A faulty ABS relay will not cause the engine problem that you are experiencing.

newsboy

Change your coils, not expensive and easy to do.