458 Please help... high idle on start

All,

2012 458 acting up with an idle that revs to redline on start.

Any suggestions on how to manage?

Any idea on what’s going on?

Is flatbed to the dealer the only option?

Thank you for your help.

 

Did another restart but blipped the throttle and now it’s normal idle.

No codes.

 

I’ve also noticed that when I’m driving and let off the throttle, the ECU will hold the RPMs.

I’m thinking this all has something to do with me pinning the exhaust valves open. At first, it sounded amazing, but after several weeks the ECU seemed to eliminate all the crackles and pops with throttle let off.

Eventually the car exhaust was simply loud and lost all of the nuances.

Anyways, I live in California and tested the exhaust with a dB meter. 95dB at idle and 122-125 dB at 3000 idle. Basically, not compliant.

For both reasons above went back to stock and car runs normally again albeit not as load.

It’s odd that no one seemed to have these issues with pinning the valves open.

 

Was present in 4,5,6,7

 

It’s pretty odd. Had multiple drives since and so far, car’s running well.

 

Spoke to a knowledgeable mechanic and he feels that the ECU would look to richen up the ratio at a minimum.

 

It’s possible, but the pins I inserted where tight and I also clamped the hose around them.

Regardless, I’ve put about 300 miles on the car with some spirited stretches with a lot of down shifts and the car is acting normally again.