Expert: Josh Fields - 6/17/2006

Question
Hi Josh,

I hope you can follow me on this. I just purchased a e30 4 cylinder bmw, 318i of coarse.

Now, When the car idles you can see and hear the revs going up and down just ever so slightly, the a/c is turned off to stop the motor compensating for the a/c.

When on the road, the car goes up through the gears but there is a very slight surge in the motor(the same as when stationary) like the timing is not 100%. It basicly surges a little as you pick up speed on the road as opposed to nice even revs through the automatic transmition.Never changes, stays like this weather it is hot or cold.

Ok, I hope that makes sense, I look forward to your response.

Regards Rob

Answer
Rob,
 Sounds like the car could use a tune-up if it hasn't been performed in the last few years.  Spark plug wires, Spark plugs, distributor cap and rotor button, and sometimes the coil.
 You should probably look for vacuum leaks as well.  

 A surge can be cause by many things, and usually it's something small.

 Hope this helps,
 Josh