I have an Opel Corsa with the I4 Z17DTR, and any time I set the revs just above idle (1000-1200 rpm) a squeaky fluttering sound - kind of like a slipping belt - comes from the engine. It goes away the instant I lift off the throttle to coast, or push the revs over 1500 rpm; mostly occurs when moving off from stationary and when I stick it in top gear for a long, high-speed cruise.

Any ideas what it might be? The fact that it happens at a specific throttle setting suggests that it'* something to do with the air intake, but I'm only guessing. There are no EML'* on the dash, and receipts say that the turbo was replaced not too long ago.


Thanks.

Maybe record it.

It might be related to the wastegate. Does it have an exposed slide on the wastegate?

Have you tried doing the same thing with the accessory belt removed? (for a very short period of time)

Would the belt squeak at that very specific rpm band?

Pic added - not overly familar with turbos, but I assume that the plunger with the green bellows at the end is the wastegate?

If that is it, make sure it has a full range of motion without sticking.

I read in another forum about a BMW that issued a squeak after being turned off, and the OP cured it by lubing the waste gate plunger.

I've hit mine with a decent shot of GT88... can they be actuated by hand, while the engine is off?

Get us a picture and I could probably tell you.