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Old 07-25-2008, 10:36 AM   #1
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some hesitation near startup and chattering problem

Hi, I bought this '99 automatic about 2 years ago. Alright, I've started to have this hesitation problem for a month now. When I start up the car and drive for the first 5-10 minutes or so, the car seems to hesitate. I would step on the gas pedal like usual, but it won't run smoothly. It would hesitate then accelerate then hesitate then accelerate, so on. Even when I am stepping on the break, it would hesitate and accelerate (probably a few inches on the spot). After about 5-10 minutes drive, it starts to run smoothly. (Sometimes I feel ridiculous because people probably think I'm showing off or something). I'm convinced that the heat (average 88-93 degrees right now) causes this problem because I still have a chattering problem with the car when I've driven for 1-2 hours or more in hot weather. It occurs especially when i'm idled in traffic.
Okay, so any ideas? The car has gone over 80,000 miles.
Hope you guys can help.. and sorry for the long right, i am a girl. Thanks.

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Old 07-25-2008, 05:36 PM   #2
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is the check engine light on???? where is the chatter coming from???

sounds like a bad tps or IAC sensor.
make sure all your fluid levels are good. oil, coolant, brake fluid, trans fluid.

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Old 07-27-2008, 11:33 AM   #3
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thanks for replying.
no the check engine light is not on. as for the fluids, they are good.
my brother believes that it could be a sensor problem too.
i went to a autoshop to try to diagnose the problem but they said everything was fine, as i have said the problems exist only during certain conditions.
and may i ask what is a tps? tried to google it, but got some other crap instead. thanks
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Old 07-27-2008, 11:53 AM   #4
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throttle position sensor
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Old 07-29-2008, 07:15 PM   #5
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I am having the EXACT problem!! I have a 1997 jeep wrangler 4.0 w/ auto, approx 110,000 miles. I have hooked it up and it's throwing no codes. So it's a sensor that doesn't read off the computer somewhere. I don't wanna spend big bucks buying sensors. The jeep runs for about 4 minutes and then starts bucking and backfiring for about 2 minutes then clears right up and runs great the rest of the time its running. but if I were to shut it off and let it sit and cool all the way down, it will do the stuttering again on start up. Has this problem happened to anyone else?
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Old 07-29-2008, 07:43 PM   #6
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mine stutters a little after initial start up but goes away in about 3 seconds or when you hit the gas
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Old 07-29-2008, 07:44 PM   #7
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Quote:
Originally Posted by Rawkon View Post
throttle position sensor
That's my guess too. That's the gizmo that reports to the computer how much you're stepping on the gas so if it gets intermittent (dirty inside) so it gives an eratic signal to the computer, the engine can stumble or accelerate roughly. If it is indeed a bad TPS which is caused when they wear inside and flakes of carbon interfere with the electrical contact, you can sometimes temporarily clear the problem by working the throttle back & forth 75-100 times which will temporarily clear off the carbon that is contaminating it internally. If that helps, then the problem is almost certainly being caused by a bad TPS.

One more thing you might try is using a can of Throttle Body cleaner to clean out the inside of the throttle body. If it's black and gunky inside, the engine won't run well. And part of that is another sensor 90 degrees CCW from the TPS called the Idle Air controller that when it gets dirty, it causes rough idle problems and occasionally acceleration issues.

The below shows you where all these gizmos are located. Either is easily removed for cleaning (only the IAC can be cleaned) or replacing (only the TPS, the IAC can be cleaned), just two small torx screws hold them to the throttle body.
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Old 07-29-2008, 08:50 PM   #8
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what about the IAC??? Ill pop mine when i get a chance and see how much carbon it has on it.
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Old 07-30-2008, 05:07 PM   #9
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my uncle owns a garage, he seems to wanna lean toward the MAP sensor. I've allread took the intake hose off and cleaned the throttle body with spary. It didn't help at all, even though it was kinda dirty in there. If any body tries something different let me know, thanks guys.

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