Well 2d I updated lfs to 0.6b and everytime I enter in a server, I can see cars running for like 2 seconds and then JOOS CAR appear on the chat screen and i am kicked out
yesterday with my old z28 I was able to play online ...

0.6B contains the following change,

Quote :

Implemented VOB mod protection (physical changes will cause OOS)

If you have made any physical changes to your version of LFS' cars, you will get the said JOOS - CAR error.

Change the VOB files back to the defaults and you'll be fine.

I've had the same problem with my LFS. It's heavily modified (texture wise, HD interiors, tinted tail lights etc), but no VOB mods. The weird part is, it kicks me out after about 5 minutes, not as soon as I join. It sucks, but I guess I have to start with a new LFS.

You can't use a vob mod

This what happens when you guys come into a cruise server or race server. Don't use VOB mod's. They may look nice but they muck up everything. From when a cop chases you or just you driving around.

Is there any way to keep the mods without getting the error?

Car mods? Nope.