m20 problem, sounds awful

[jax0r]

So I started my 325is this morning, and low and behold it idled rough. I thought little of it as it has been awfully cold and rainly lately. However, when I step on the throttle, the whole car shakes some and it has a hard time accelerating. There is a noticable power loss and my motor sounds quite similar to a Subaru WRX flat 4 when accelerating. The weird thing is the car decelerates smoothly and seems fairly smooth above 3500-3750 rpm. I came up with the possibility of a fuel delivery or spark problem, but all in all am quite puzzled. Has anyone else had this problem? Any help would be greatly appreciated. Thanks

[Jordan]

Sounds like you are running on 4 or 5 cylinders.

Pull the plugs and examine condition, replace if needed. Check for good spark on all of them.

[325is_e30]

i had a similar problem. checked compression, all cylinders were at 150psi. got a new cap and rotor, that didnt work. then i took the intake manifold off of another e30 i had and swapped that with injectors and all. it runs fine now. my old intake was filled with greasy black stuff (carbon build up?), im not sure what that was from? so im not really sure what it was but replacing all that fixed my problem... does anyone know what caused it though?

[Jon325i]

While you're inspecting things, check for vacuum leaks too. I've had my car act in similar fashion before. Turned out to be a split on the underside of the intake rubber tubing between the AFM and the throttle body.

Jon

[jax0r]

I hope it's just not a timing problem. Does anyone think it may be a loose or stretched out timing belt?

[Bryson]

While you're inspecting things, check for vacuum leaks too. I've had my car act in similar fashion before. Turned out to be a split on the underside of the intake rubber tubing between the AFM and the throttle body.

Jon