99 Sentra High Rpm While In "park"

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latinman - 25 Nov 2007 21:41 GMT

I have a 99 Nissan Sentra 1.6L with automatic engine and 125K miles.

When I start up the engine and while in "PARK", the engine RPMs clim
to around 1,400-1,500 RPMs and remain there, until I turn the A/C on
the RPMs drop to about 1,000

Then, when I put the vehicle into "DRIVE" the RPMs drop to around 1,00
(without the A/C on), but drop to around 800 when I turn it on

:confused: Can anyone tell me what could be wrong? :confused

I just replaced the spark plugs, wire set, and rotor

Thanks

--
latinma

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al - 26 Nov 2007 03:37 GMT

On Nov 25, 4:41 pm, latinman <latinman.30m...@no-
mx.cardealerforums.com> wrote:

> I have a 99 Nissan Sentra 1.6L with automatic engine and 125K miles.
>
[quoted text clipped - 16 lines]
> latinman's Profile:http://cardealerforums.com/member.php?userid=581
> View this thread:http://cardealerforums.com/showthread.php?t=103889

What happens if you start the car, leave it in PARK, never turn on the
AC and let it warm up? Are you saying that it will stay at 1500 rpm
even when fully warmed up? If so, then you have an idle problem
(e.g.vacuum leak, dirty/bad idle air control valve etc.). Al

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latinman - 26 Nov 2007 19:51 GMT

Exactly Al, when I turn on the engine and let it warm up for at leas
5-10 mins., the RPMs will remain in the 1400-1500 RPMs range. The RP
will not drop even after fully warmed up, only when I put engine i
DRIVE then RPMs drop to around 1000 RPM

Thanks for your reply, I'll check those items out

--
latinma

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al - 27 Nov 2007 03:02 GMT

On Nov 26, 2:51 pm, latinman <latinman.30o...@no-
mx.cardealerforums.com> wrote:

> Exactly Al, when I turn on the engine and let it warm up for at least
> 5-10 mins., the RPMs will remain in the 1400-1500 RPMs range. The RPM
[quoted text clipped - 8 lines]
> latinman's Profile:http://cardealerforums.com/member.php?userid=581
> View this thread:http://cardealerforums.com/showthread.php?t=103889

Certainly you'll want to ensure that both the throttle body and idle
air control valve are not dirty. Usually though when they get clogged
the rpm gets erratic. Another possibility is that some sensor, such
as a temperature sensor, is either faulty or its signal is not getting
to the computer causing the computer to think that conditions are such
that it needs to run the engine at high idle. Looking at the data
stream with a scan tool would be very revealing. Good luck. Al

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codifus - 29 Nov 2007 16:56 GMT

On Nov 26, 2:51 pm, latinman <latinman.30o...@no-
mx.cardealerforums.com> wrote:

While the revs are high, did you try just hitting the gas pedal for a
moment? Usually what then happens is that the the car revs higher for
a sec then settles back down to its normal idle speed. This is another
symptom of the throttle body and idle air control valve being dirty.
Not really a big issue, just a damn annoyance. Easy to clean, just
search for threads about cleaning your throttle body.

CD

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Tim - 30 Nov 2007 00:11 GMT

Something is wrong with the wire that opens the air/fuel mixture, it is set
too short (or set to widely-open the gate). It's normal to see the RPM
dropping when AC is engaged because AC takes horse power away, when your
car's power is not being used it is turning faster. You got to adjust this
air/fuel control wire to idle your engine as low as possible, about 600-700
is best so you car will consume less fuel.

I went through this cycle many times, I'm almost sure of this problem.

> Exactly Al, when I turn on the engine and let it warm up for at least
> 5-10 mins., the RPMs will remain in the 1400-1500 RPMs range. The RPM
> will not drop even after fully warmed up, only when I put engine in
> DRIVE then RPMs drop to around 1000 RPM.
>
> Thanks for your reply, I'll check those items out.

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