Rough Idle and EnginePower Loss - BMW Forum

Deggles99 · 10-26-2003, 05:51 AM

Hi, Im hoping an experienced E30 mechanic might be able to shed some light on this problem I have please.

I put my E30 316i into storage for 12 months, it was running really well when it went under wraps in a dry storage area. Last week I took it out from storage and it started fine, first turn of the ignition, I couldnt believe it. Hovever it was running really lumpy.

I took it for a short slow drive hoping it would clear, but it didnt. The tank was almost empty so I filled it up with fresh fuel thinking this would resolve the trouble, but it didnt. The engine completely lacks its usual power and has a lag between pressing the accelerator and responding, even when it does respond the acceleration is really poor.

It had to go for an MOT today, which it passed, but the mechanic said it was really low on CO emission, so he tweaked the screw on the airflow meter (I think ? ) to try and correct it. However there was no response to the CO level. He added that there was too much air getting into the mixture. He concluded the ECU might be faulty or just hasnt kicked in yet.

Would this be a good assumption? Would ECU's fail just like that in storage ? Would a bad ECU give these symptoms ?

I would be very grateful for any pointers please as to what the problem might be as the car is difficult to drive.

Cheers, Deggles

KC Ron Carter · 10-26-2003, 11:08 AM

BMW engines are positive crankcase ventalated.

That means the intake and the crankcase are connected.

That is why it starts to run lean if you pull the oil dip stick out when at idle.

I am sure you have a gasket leak allowing to much air in the fuel air mixture.

I like to use either in a spray can, starting fluid, to locate the leak.

When you spray it on the leak the engine will speed up.

Good luck,

Deggles99 · 10-26-2003, 12:55 PM

Thanks very much for your help. Where, typically, should I look for a leak ?

Cheers

Darren (Kent, England)

m42technic · 10-26-2003, 02:19 PM

Quote:

Originally posted by Deggles99@Oct 26 2003, 12:35 PM
Thanks very much for your help. Where, typically, should I look for a leak ?

Cheers

Darren (Kent, England)

Check all your vacuum hoses, the intake bellows, and the intake manifold.