miller89

All, I need some help. I've been having this issue with my car for a little while but it got much worse this morning. When the temperature is about 55 degrees or lower in the morning and I start my car after it's been sitting all night, it will start right up, hit about 1200 rpm then start to bog down a bit to 900 for about 5 seconds or so then to back up to 1200. After that the car runs fine, I've had no other issue.

However this morning I started my car up and it started to do that again and then I heard what sounded like a small boom coming from the motor. Apart from scaring the hell out of me nothing else happened, I didn't get a check engine light or anything. It ran just fine all the way home. I have a jlt cai, an off road x pipe and bama tune.

I was wondering if anybody had any ideas. Anything will be greatly appreciated. Thank you guys

Nuke

If you were rolling I'd say you had broken the sound barrier...

No idea, brother. May be something specific to the 5.0 so hopefully we'll get some other 5.0 owners that have an idea. There was a TSB on the 4.6L for a "whoot" or whistle on cold startup but that's all I got...

miller89

Thanks brother I appreciate the info. I just don't understand it. I've been racking my brain over this for a few months, I don't understand what it is. And the local dealership probably won't be willing to help since I have mods.

Andy13186

What is your altitude?

what weight oil are you using?


did it sound like an exhaust backfire?

miller89

I live in co springs, co. It's about 6000 feet. I run 5w20 amsoil. And no not a backfire. It came from the motor.

dominant1

Data log it send it to bama see what they say, if it doesnt boom every time focus on the tune!

clowe1965

Does it continue to have the oscillating idle after youve started driving it? When you say boom, was it closer to a gunshot or a drum being struck?