I have a weird problem I can't figure out.

The first start of the day will take 4-10 seconds. Once it starts it runs fine. No Smoke. Idles Fine. no CEL. The longer the car sits the longer it will take to start. The rest of the day the car will start fine.

Seems like it is losing fuel pressure. I replaced the fuel pressure regulator, and the issue was not fixed. I am suspected the fuel pump next. Does anyone have any other ideas?

The car has new plugs, coils, air filter. Issue seemed to get worse after the coils were changed. I think it's a coincidence. seems to get worse with cold weather. The new coils are Denso, OEM. from rock auto. It doesn't make sense that coils would be the issue and only be problematic on the first start of the day.

love to hear your ideas.

 

Funny enough I have that issue with my 2014 S4...
but I'm due to do the pcv and water pump and tstat...not sure it's linked
but maybe vacuum related after sitting overnight.
If I turn car off and right back on it's immediate.

 

what's your battery's voltage in the morning?

 

car has a brand new duracell battery.

 

it could be related to vacuum, but I don't think manifold hold vacuum for hours on end.

 

that wasn't the question, you could have a parasitic draw after your car sits overnight causing the voltage to drop

 

there are contraindications for having a bad battery. Aside from being 3 months old, I have strong consistent cranks, and the car starts fine immediately after struggling for 6+ seconds on startup