Rattling noise at start up
 

I just changed OFT tunes. I went from OFT E85 stage 2 version 4.03 to 93 gas stage 2 v,4.03. I get a very scary metallic rattling noise that seems to be coming from the center of the engine bay for about 30 seconds when I start the car when it is cold. The noise goes completely away after 30 seconds. Car runs normally after that. I have driven over 150 miles since changing the tune. Any help?

Never mind, Car started normally today. I'm guessing the ECU needed more time to learn the start procedure.

Do you have a recording of the noise?

Sorry , no recording, At first it sounded like rod knock ,I was devastated. It went away as i raised rpms. Just happened at idle. I am guessing maybe fuel knock from wrong timing advance

... just the normal cold start at low temperature?

I wish. It was loud and terrifying, thank god it stopped. Although I drove a hundred miles or more, I only had 2 engine starts since changing tunes. Thinking that the ecu starting and warmup learning had a glitch. Thanks all for this forum, it's great!

How cold/warm was it outside?

Do you have any exhaust customizations?

How’s your dipstick looking? (Seriously)

Cool, 40 degrees
OFT header UEL, and down pipe
Fresh Mobil1 5w-30. 1/2 qt high on the dipstick, lots of track driving.
It has positively stopped making any strange noise at start up since