roastedass

my engine on my 05 mustang hesitates when i first start it up and its cold outside and i go to give it gas, it sounds like its gonna dies almost, but once its warmed up, its fine.....i took it to the dealer and they said they found nothing, so my question is, is this normal or does anybody have the same problem???

S197 V6

Ive noticed that alot recently with my car as well...

vistablue mustang

You know I noticed that last year with my 06, on really cold days the car would barely turn over and sometimes not start on the first try. I would always start on the second try and be fine for the rest of the day. I also took talked with the service department about this and they kept it over night when it was cold but told me they had no trouble starting it, since then we have moved and I keep my car in our new garage and have not had the problem since, but it bothers me to know that it was never fixed. Please if you find anything out let us know!

Mustang05

mine dies... or wont start.. i have to keep turning the key on and off the get the gas flowing in the lines and then sometimes push the gas a little when i try to turn it over.. shouldnt have to do that with these cars there not carbarated

05retro

Noticed it with mine recently to. Hmm most of us so far with 05's and just noticing it recently.

Mine used to be kept outside all day every day for the last two years and i dont remember it happening ever before.

Mustang05

Same here ^ i never had to do all this "work" to get her started in the winter...*sigh.

official_style

mine starts fine, but kind of bucks a little when its cold if i drive it. just let it warm up. i am betting that this is the o2 sensor heaters wearing out. ill bet if you put in new FORD oem sensors it wont do it.

05retro

Thanks for the idea. I'll have to try that out. If I were to pick up a Bosch sensor from Advance does anyone know the part number?

enzo51

Hi,

do not bother changing the O2 sensors, they have not impact on the starts.
If the cars does not crank:
old or too cold battery

If it cranks but does not start:
old spark plugs or engine calibration issue (this is a problem with the engine calibration, there is nothing you can do, unless Ford releases a new calibration for the engine)

lodom

I wonder if any of the cold start paramaters could be adjusted in a custom tune? Maybe now the engines have some miles on them they need more fuel when cold to run properly and this didn't show up in Fords cold testing of the car.

metroplex

I bet it is the battery. The Group 40R/96R batteries were sized for small I4/V6 engines (they are used in some of Ford's FWD cars and Mazdas IIRC) and not for V8 engines especially in cold weather. Notice how the batteries in the S-197s got battery blankets? It's to prevent/slow down freezing of the batteries in cold weather, as well as to insulate the battery from engine/exhaust heat. I started up my Dodge Aries K-car (2.5 I4) with barely enough voltage to keep the dome light on!!! It went crrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrk crrrrrrrrrrrrrrrrrrrrrrrrk crrrrrrrrrrrrrrrrrrrrrrrrrrk CLICK vrrrrrrOOOOOOOOOOOOOOOMMMMMMM.

On a 302 V8, unless the battery is in good shape, you're not going anywhere.

On almost every other Ford with a V8 engine (Crown Vic, E-series, F-series), Ford has typically used a large battery like a Group 65 (1000 Cranking Amps versus the 500 Cranking Amps with the Group 96R).

official_style

do not use bosch sensors in this car. i tried them, and the cel would not stay off. trust me, use only ford oem ones. the problem posted in this thread was that the car will crank, and start, but then run rough and hesitate. how would the battery cause that? the car turns the o2s on after like a minute of it being started. when i put my LT headers in, my car would run rough for like 10 mins, until it was full heated up, or i revved it up a bunch. the o2 sensors have heaters in them, and they were worn out so they were being turned on but no warm enough to read. i changed one of them that was giving a code, and problem solved. i datalogged the car when its cold, and you can see the new o2 sensor starts reading correctly way before the one that i didnt replace. i am almost positive this is whats causing the problems.

OKCMustangGT

If it is COLD outside, why are you driving off before you let the car warm up?
That is pretty much SOP for ANY car.
You also mention that you give it gas at start-up ? DON'T. As stated previously, non-carburetor cars don't need to be given gas at start-up.
The only problem I have is when its COLD (near freezing/sub freezing temps) the car does not start as prominently as when warm but has NEVER failed to start on the first turn of the key.
I also took off once before letting the car warm up and it kind of hesitated between 1st - 2nd shift.

metroplex

The Bosch O2 sensors delay the warm up for about 2-3 minutes and are more suited as rear O2 sensors. The Ford/OEM O2 sensors start switching within 10-30 seconds of a cold start, right when the engine switches from open loop to closed loop at idle and no load.

Check the condition of the battery (voltage at rest should be 12.1V-12.8V DC) at the very least. It could be your O2 sensors but you need to datalog it to see what is going on. It could also mean you are running excessive lean/rich.

jt14894

Whenever I startup my car, I always give it at least 2 minutes to warm up, or when I see the temp needle start to move, before I begin driving and I NEVER rev it up to speed up the warming.
Once its warmed up, it runs fine and there's no hesitation whatsoever.
IMO, starting up and reving up a cold engine is bad because the oil hasn't begun to circulate and this could lead to the internal parts wearing out more quickly, correct me if I'm wrong for you mechanics out there.
I've seen people in the mornings start the engine and take off as if they're at a track or something.
I thinking these people are idiots.
Anyway, that's my 2 cents.

05retro

For me the problem isnt when i step on the gas. Its the moment the key is turned. For about a second it sounds like i have a dead battery. Now mind you the car wont be sitting for several days, more like 8 or 9 hours. After the second or two is over she sounds normal. No revving the gas for me. She warms up for at least 5 minutes or more depending on how cold it is.

Vermillion06

I have no hesitation or starting problems with mine on cold mornings... It roars to life on the first turn of the key and accelerates smoothly just like always.

MooreGT

whats a cold morning? FL mornings just let me see better 0-60's.. haha.. sorry guys. hope its figured out!

vistablue mustang

This is the exact same problem I had with my 2006 in the cold when it was outside, not sitting for days just about 10 hours after I come home and then go to leave again in the morning. I hope someone gets this figured out, as I never had any luck. Maybe if this post gets passed along to Ford they will look into it.