318i Idle Issues - Help Required!

[Scottlaw]

Afternoon Folks

Tearing my hair out with this one. Long time member of the forum but tend to not post a whole lot!

Anyhow here’s the issue!

I recently got some work done to my 1990 318i which including dropping the front subframe to restore, new links, tie rod ends etc. I also had the the intake taken off to be repainted etc.

The car was mechanically running great before but now it’s not.

When on the move the engine performs as it should, however when idle the engine is shaking like crazy.

The revs are holding steady at the normal 600-650rpm and it seems to have enough power when driving.

I took off and cleaned the ICV but this didn’t help. If I rev to 1000rpm or so when stationary the shaking stops.

Any possible solutions or things to check would be massively appreciated!

Thanks in advance

Scott

[BenHar]

Check for air leaks on the intake side.

Ben

[Scottlaw]

Thanks Ben.

I have checked. Would the revs be unstable with an air/ vacuum leak?

[fixedwheelnut]

Thanks Ben.

I have checked. Would the revs be unstable with an air/ vacuum leak?

Yes any air leaks between the air flow meter and the engine will cause a weak mixture and erratic running.

Get a smoke test done and check the engine earth if they dropped the subframe they may have disturbed it.

I would be getting the garage that did the work to double check what they did if it ran fine until they touched it.

[BenHar]

Thanks Ben.

I have checked. Would the revs be unstable with an air/ vacuum leak?

Yes any air leaks between the air flow meter and the engine will cause a weak mixture and erratic running.

Get a smoke test done and check the engine earth if they dropped the subframe they may have disturbed it.

Or spray round the intake with brake cleaner or lighter gas when it's idling. If the revs go up there's a leak.

Ben

[Contours]

A rev of 750 rpm at idle when warm would be normal for this engine.