Rough Startups

[g_908013]

I recently purchased a 2015 genesis (4 door) with 27,600 miles and I notice that after sitting for awhile and then starting up the start is rough, instead of a smooth process. What could cause rough start ups?

 

[T_E]

Same thing I am experiencing with 2012 Equus V8 after engine replaced. Same day starts are quick, after sitting more than that, takes a couple seconds to crank. (original engine didn't do this) Took to dealer and told him to look for fuel pressure leakdown. Nothing found, just living with it.

Also, check battery capacity, just in case.

 

[RyanB]

You may want to run a tank of premium with a bottle of Chevron Techron. I also used the spray Sea Foam directly into my intake before and it helped smooth out my idle. If its simply carbon build-up this may help.

 

[carguy75]

I recently purchased a 2015 genesis (4 door) with 27,600 miles and I notice that after sitting for awhile and then starting up the start is rough, instead of a smooth process. What could cause rough start ups?

Probably the gas if you use regular, because 87 octane losses it punch after a while when it becomes stale and just causes the knock sensors to go crazy and pull back engine timing which makes the engine idles rough.

A fresh tank of gas may help. I personally just use 93 octane and my engine runs very smooth to the point that I only can hear the injectors tick. Idle is smooth.