My cCar mMakes a sStrange nNoise wWhen i launch iI Start It

Title capitalization rules.

Note: titles are usually kept pretty short. An alternative title might be: Car Problem

My car makes a strange noise when i launchI start it.

You can "start" or "turn on" a car.

"Launch" is when something goes from 0 to traveling very fast in an instant. Rockets launch. If you launched something else, it would be like you threw it really fast (imagine picking up your car like The Hulk and throwing it down the street)

When i wasI noticinged this i, I decided to take it to a (car) mechanic.

"Mechanic" is automatically understood as a mechanic who works on cars, so you don't need to mention "car"

I did as iI plant itned.

"I" is always capitalized

Yesterday i, I took it a carmy car to a mechanicer, i and left my carit there.

I thougtht it hasd a turbo problem because this strange noise typically indicates that.

When iI was arrivheading home, the car mechanicer called (me,) and said iI clould pick up my car tomorrow.

"Heading home" is a lot more natural than "arriving home." The latter sounds very formal. You could omit "me" and still be understood

It has/had a servo problem instead of trurbo.

Here, you could speak in present or past tense (it has, it had). "Has" because it is still a problem currently as you write, and you are returning us (the reader) to this present moment, or "had" in past tense to be coherent with your story retelling. Personally, I would have said "it had"

So today iI am going to pick up my car, i. I am really happy because a servo problem is more cheaper problemto fix than a turbo problem.

For adjectives that take on -er and -est suffixes, you never use "more" or "most" as it's already built into the word. That is to say that "cheaper" already means more, and "cheapest" would already mean most.

My car makes a strange noise when i launchI start it

''I'' always as Capital letter

My car makes a strange noise when i launchI start it.

When i wasI noticinged this i, I decided to take it to a car mechanic.

simple past

I did as iI plant itned.

Yesterday i, I took it a carmy car to the mechanicer, i and left my carit there.

I thougtht it hwas a turbo problem because this strange noise typicusually indicates that.

When iI was arriving home, the car mechanicer called me, and said iI clould pick up my car tomorrow.

It haturns out it’s a servo problem instead of truboa turbo problem.

So today iI am going to pick up my car, i. I am really happy because a servo problem is moreuch cheaper problemto fix than a turbo problem.