Engine problem - revs up at random

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Old 08-30-2005, 06:49 PM
cloaker's Avatar
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Engine problem - revs up at random

Hey guys, I'm sorry if this is elsewhere, but I tried searching and couldn't find it.

While I'm driving the engine will rev up the rpms. If I stop at a light, sometimes, not always, it will buck forward when the rpms go up. If I shift into neutral, it rocks up to 2000, if I punch the gas, it goes to 3000, if I punch the gas again, it drops to <1000. When I'm driving, sometimes I can feel it trying to take off as if I'm giving it gas.

Engine light has been on and off for the entire time my dad owned it. Recently, it won't go off, I reset it twice so far and it comes back within 1 hour or about 30 miles or so.

Any easy things to check for?

Its a 1999 4.6L automatic.
 
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Old 08-30-2005, 06:50 PM
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clean the IAC and check your hoses for vacume leaks
 
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Old 09-04-2005, 03:17 AM
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Just guessing here. Could be the throttle position sensor. It tells the computer to accelerate etc. so if it malfunctions it might make the rpms go nuts.
 
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Old 09-04-2005, 04:59 AM
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Originally Posted by fasterhorses
Just guessing here. Could be the throttle position sensor. It tells the computer to accelerate etc. so if it malfunctions it might make the rpms go nuts.

its possible but TPS doesnt control the throttle body. check for Vacume leaks in the hoses attached to the engine, and clean the IAC Valve
 
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Old 09-04-2005, 04:39 PM
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This may sound a bit harsh but why would you 'not' have the codes outputted to see what areas is causing the problem for so long?
Did you think the fault would just go away by rebooting the computer not to mention being a danger to drive..
It doesn't work that way.
Get the code then look at the area it referrs to.
I have an idea but you need to learn this.
 



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