M30 throttle "lag" / slow response when giving gas from idle

[AlexanderM]

Hi,
I have a European 530 with the M30B30 engine. It runs well, definitely has the power it's supposed to, and I'm happy with it. However, there's a very clear lag when pushing down the throttle pedal from idle. When it's "revving" (for example holding it at 2000 RPM), and the pedal is then pushed, there's almost no delay, so the issue is just related to the idle somehow.

When giving it gas from idle (most pronounced when almost flooring it), it sort of stumples and sounds like it's about to drown, just for a split second, then the revs go up as they're supposed to. I estimate the lag to be around 0.5 seconds. This also makes for very difficult downshifts, as I need to wait for the lag to "clear" until I clutch in after selecting gear (and giving revs to match).

Also, when I start it from cold, it sometimes fluctuates in idle just for the first 10-15 seconds or so. It goes like wrooOOOOoonn....wrooOOOOoonn.... first up to 800 RPM for a second, then down to ~600, then it "catches it", and goes up to 800 again for a second, and so forth. As said, only for about 10-15 seconds, but maybe this could be related. Furthermore, it takes about 3-4 seconds for the oil pressure lamp to go out after starting it, is this normal?

The idle is rock solid as soon as the engine is just a bit warm.

Now, dummy logic would dictate that I clean/replace my ICV . But I don't have any experience yet with working on this engine, so I'd appreciate some other suggestions or experiences with this issue.

Thanks.

[Paul in NZ]

ICV very easy to clean.You need some carb cleaner.The Icv is the cylindrical device that branches off the intake boot with a couple of wires on the end.Inside a sleeve needs to spin to allow a cutout to let air through,but this can get "gummed up".My 535 has a very similar lag just off idle but only if you give quite a foot full.As far as gear down changes go dont let it drop down to idle,if you just back off the throttle a bit as the clutch goes in the revs rise of there own accord and match speed almost automatically.You dont need to "blip" the throttle

[AlexanderM]

ICV very easy to clean.You need some carb cleaner.The Icv is the cylindrical device that branches off the intake boot with a couple of wires on the end.Inside a sleeve needs to spin to allow a cutout to let air through,but this can get "gummed up".My 535 has a very similar lag just off idle but only if you give quite a foot full.As far as gear down changes go dont let it drop down to idle,if you just back off the throttle a bit as the clutch goes in the revs rise of there own accord and match speed almost automatically.You dont need to "blip" the throttle

Where excactly is the ICV? I'm having a hard time finding any pictures or diagrams. I have a Bentley manual and ETK, but no luck finding it