Car is hard to start, then sputters, then runs fine... any ideas - LS1TECH

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Car is hard to start, then sputters, then runs fine... any ideas

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Old 03-12-2008, 11:16 PM   #1
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Default Car is hard to start, then sputters, then runs fine... any ideas

I'm trying to help a buddy out with his car and I'm kind of stumped. Here's what happens: On a cold start it cranks longer than it should need to and then sputters to life. Sometimes you need to feather the throttle to keep it running but sometimes it's fine. Upon startup I notice a strong gas smell as well as smoke coming from the tailpipe, more than likely unburned fuel. Once it gets past the sputtering and choking which last only for about 15 to 30 seconds it calms down and runs just fine. Every once in a while all of the sputtering will cause an Check Engine Soon light to turn on for misfire, then it goes out after a few key cycles. Once the car is warmed up it will start right up as soon as you hit the key, but if you let it sit and cool off for an extended period of time it will be hard starting again. Any of you guys have any ideas on what this sounds like? Cold or hot weather doesn't affect this condition either way. It acts the same regardless of the temp outside. Funny enough cold weather might help it slightly.

Any help would be great. It's his DD. Thanks guys.
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Old 03-12-2008, 11:24 PM   #2
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fuel pump mine did that before it went out, or just a tune up.
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Old 03-12-2008, 11:34 PM   #3
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Originally Posted by 98 T/A raptor View Post
fuel pump mine did that before it went out, or just a tune up.
But if it was a fuel pump wouldn't it have issues while running too? It should have just as hard a time maintaining fuel pressure as getting it there under cranking conditions, right? Same with a tune-up. The car runs perfectly fine once started.
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Old 03-12-2008, 11:35 PM   #4
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plugs I would say
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Old 03-13-2008, 12:30 AM   #5
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Checked the plugs out. They all look great.
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Old 03-13-2008, 07:31 AM   #6
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not plugs. basically the car is stuck in cold idle or warm idle loop when it isn;t supposed to be. check for codes.

sometimes it's either and air or coolant temp sensor that causes this. sometimes it's just a dirty throttle.
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Old 03-13-2008, 10:14 AM   #7
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My V6 does something similar, but without any SES light and nothing odd out the tailpipe. Was told it could be fuel pressure drops off when the car sits since it acts like there isn't any gas.
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Old 03-13-2008, 10:40 AM   #8
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i would say ignition coil but that wouldnt cause unburned fuel to go out the back end. id recommend a full tune-up
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Old 03-13-2008, 11:16 AM   #9
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umm ok .. one more time.

you're having a start up issue related to the fact that the computer does not know if the car is hot or cold... clean the throttlebody and mass air..... check for codes.

you could have a bad intake air temp sensor.

ignition coil> c-mon guys
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Old 03-13-2008, 03:13 PM   #10
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Okay thank man. I'll check into it. It makes sense. No codes by the way.

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umm ok .. one more time.

you're having a start up issue related to the fact that the computer does not know if the car is hot or cold... clean the throttlebody and mass air..... check for codes.

you could have a bad intake air temp sensor.

ignition coil> c-mon guys
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Old 03-13-2008, 10:21 PM   #11
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dont think its a tune up problem. obviously the computer is dumping the wrong mixture until it figures out what the hell is going on.
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Old 03-13-2008, 10:30 PM   #12
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dont think its a tune up problem. obviously the computer is dumping the wrong mixture until it figures out what the hell is going on.
That's what I keep thinking but I'm just not sure why it's confused and there's no codes so I'm not sure where to look
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Old 03-14-2008, 12:30 AM   #13
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Leaky fuel injector maybe, lets the rail dain into manifold while sitting then the you try to start in an already flooded condition. Try pressing the gas peddle to the floor before you put the key in and hold it there. Then start this is the normal start for flooded engine. Maybe a good injector cleaning will fix it. Good luck
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Old 03-14-2008, 01:08 AM   #14
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Strong gas smell, sputtering, and smoke out the tail pipe. Yep, you've got a case of motorfloodititis. Injector driver in the PCM is causing the injectors to be stuck open. What BadGTho said is right. Clean the MAF and check O2 sensors.
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Old 03-14-2008, 07:34 AM   #15
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Quote:
Originally Posted by KENS_SS_4 View Post
Leaky fuel injector maybe,
dude. seriously.

please explain how that's even remotely possoible as a cause.
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Old 03-14-2008, 07:22 PM   #16
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could it be the crank senser
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Old 03-15-2008, 03:30 AM   #17
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Quote:
Originally Posted by BadGTho View Post
dude. seriously.

please explain how that's even remotely possoible as a cause.
A fuel injector is a normally closed electricly opened valve. They can leak in there normally closed condition Dude.
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Old 03-15-2008, 03:33 AM   #18
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Quote:
Originally Posted by KENS_SS_4 View Post
A fuel injector is a normally closed electricly opened valve. They can leak in there normally closed condition Dude.
Read what you just said.
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Old 03-20-2008, 05:32 AM   #19
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Quote:
Originally Posted by Rushin View Post
Read what you just said.
Another one

Leak is a "malfunctioning condition" in which something passes that is supposed to be controled not to pass.

Rushin, at least you did'nt say Dude.

Last edited by KENS_SS_4; 03-21-2008 at 07:15 AM.
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Old 04-07-2011, 06:58 PM   #20
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98Redbird

Did you ever solve this problem and if so what was the fix? I've have the exact same thing happening to me now. Thanks for any help you can give me.
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