I just bought an S4 n/a, that's having trouble running in first and second gears. It feels like the car is actually "bucking" a little bit through those. The revs are jumping drastically (bouncing 500 rpms up and down). However, the problem doesn't seem quite as bad if I give it more gas. By the time I get to third gear, the problem is gone. However, the problem persists even when it's been running for a while. I had one friend that told me it could be a result of faulty fuel injectors. Any thoughts?

 

how many manual cars have you driven? im real drunk right now., but it kinda sounds like your new to the clutch...
or maybe im just an *** hole...
but anywho, its has nothing to do with your fuel injectors, and everythin to do with possibly needing a new clutch.

 

If it's happening when the clutch is already engaged and you're just crawling along slowly then it's probably the driveline mounts flexing too much. They get soft and sometimes break in their old age. In the first few gears there's a larger torque multiplication making it worse. What happens is the mounts flex and this causes the engine to rock back and fourth causing the bucking. Subarus are particularly bad for this, I know, my mom's had 2 now, and they both did it pretty badly. Stioffer engine, transmission and differential mounts should help.

If it's happening when you're letting the clutch out you need to be smoother, or it might be something wrong with the clutch. Stiffer engine, transmission and differential mounts will probably help here too. You can get the Mazda Competition ones from Mazdatrix, or you might be able to get them from the dealer.

 

Thanks, guys!

It's definitely not the clutch; took it to a mechanic, and he said my clutch is solid. I think cool as crap may have very well nailed it; A large part of the problem was the way I was using the clutch. Turned out I wasn't easing it out gently enough, and not giving quite enough gas while letting out the clutch.

Black91, thanks. I may have to try stiffer mounts. And the problem's not half as bad now that I've gotten smoother