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High RPM in Park & Neutral


 
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97xjcrawler
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Joined: 17 Oct 2006
Location: Salina,KS

PostPosted: Mon May 28, 2007 10:25 pm    Post subject: High RPM in Park & Neutral Reply with quote

Hey everyone, just recently in my 97 XJ auto when I put it into park or neutral it will rev up to 1200 rpm instead of the usual 650-750 rpm range. it doesnt do it every time, but fairly often. any help would be appreciated!!!
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Glowyrm
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Joined: 27 Mar 2007
Location: Long Island NY

PostPosted: Tue May 29, 2007 5:47 am    Post subject: Reply with quote

check the connectors for the TPS and IAC. If it drops you might luck out and have a bad pigtail. If that's not it check your TPS voltages and clean the IAC and Throttle body.
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'87 XJ Chief w/tow pack. Dana 30/44 f/r
3.5" lift 4.88 gears NP242 t-case
Numerous junkyrd doodads
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Orangeamc13
Got Rev Limiter?
Got Rev Limiter?


Joined: 20 Feb 2006
Location: East Springfield, Massachusetts - U.S.A.

PostPosted: Tue May 29, 2007 8:06 am    Post subject: Reply with quote

IAC


X2

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97xjcrawler
Member


Joined: 17 Oct 2006
Location: Salina,KS

PostPosted: Tue May 29, 2007 12:43 pm    Post subject: Reply with quote

I just recently cleaned my throttle body and my IAC before this problem first occured. I will check all the connections though.
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5.9 andy
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Joined: 15 Feb 2007

PostPosted: Tue May 29, 2007 7:41 pm    Post subject: Reply with quote

my dads toyota pick up dose that 2 when in park or netural, it dosent go up that high, mabe only like 150 to 200 RPM's higher, but can definatly higher, i dun know, it dosent have a tack.

BTW its a 1984 2wd pick up.
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Glowyrm
Member


Joined: 27 Mar 2007
Location: Long Island NY

PostPosted: Wed May 30, 2007 5:57 am    Post subject: Reply with quote

That sound like just the drag from the auto. Most autos will do that.
_________________
'87 XJ Chief w/tow pack. Dana 30/44 f/r
3.5" lift 4.88 gears NP242 t-case
Numerous junkyrd doodads
31x10.5's
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5.9 andy
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Joined: 15 Feb 2007

PostPosted: Wed May 30, 2007 3:51 pm    Post subject: Reply with quote

thats waht i figurd with pop's truck.
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Glowyrm
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Joined: 27 Mar 2007
Location: Long Island NY

PostPosted: Thu May 31, 2007 5:48 am    Post subject: Reply with quote

I was tought that the torque converter works like a mixing bowl full of cake batter. If you get the mixer spinning at a good clip and let go of the bowl the bowl will spin, but not at the same speed. A little energy is lost to fricton, therefore heat. When you place the tranny in park/neutral its like placing the bowl on a lazy suzan(less fricton due to the fact the main shaft can rotate freely) therefore less drag on the engine, the engine returns to it's normal idle. Most modern cars have the computer adjust the idle and/or reduce drag in the tranny electronicly to eliminate this effect. Sorry if I'm lecturing, Class dismissed. Shocked
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'87 XJ Chief w/tow pack. Dana 30/44 f/r
3.5" lift 4.88 gears NP242 t-case
Numerous junkyrd doodads
31x10.5's
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97xjcrawler
Member


Joined: 17 Oct 2006
Location: Salina,KS

PostPosted: Thu May 31, 2007 10:06 pm    Post subject: Reply with quote

Im not sure why it would start doing it all of a sudden though. and it doesnt do it every time I put it in park or neutral. Thanks for the help so far, but I am trying to pinpoint where the problem lies. I could leave it be but I am the type of person who likes to have their auto running in top condition
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Glowyrm
Member


Joined: 27 Mar 2007
Location: Long Island NY

PostPosted: Fri Jun 01, 2007 4:31 am    Post subject: Reply with quote

something might be crapping out, but not toast yet. There's no real shadetree way to test the IAC, but the connections and the TPS voltages are all fair game. It is something to look into, because if the IAC goes, so does your fuel economy and, most important, the strain on the tranny and brakes will lead to future problems.

Here is the downloadable proceedure for checking the TPS.
http://www.lunghd.com/Downloads_and_Links/Downloads.htm
_________________
'87 XJ Chief w/tow pack. Dana 30/44 f/r
3.5" lift 4.88 gears NP242 t-case
Numerous junkyrd doodads
31x10.5's
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jk333
Member


Joined: 17 Jun 2007

PostPosted: Sun Jun 17, 2007 8:41 pm    Post subject: Reply with quote

my 89 did the same thing only more extreme, like up to 2000 RPM. the Jeep dealer can plug in a code reader and reajust your TPS. However, the TPS might be going out
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lakeland713xj
Member


Joined: 04 May 2007
Location: middle of no where florida

PostPosted: Thu Jun 21, 2007 6:14 pm    Post subject: Reply with quote

are you accedentlly hiting the gas when hitting the brake..... ive been known to do that and wonder what the hell was going on...i do have a size 14 shoe..... so mabey its a case of big feet????




figure i would throw that out there ...mabey its not all that bad....helkl its funn to be optimistic
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jeepster575
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Joined: 31 Aug 2007

PostPosted: Fri Aug 31, 2007 7:17 pm    Post subject: Reply with quote

Might want to check for any air leaks in vacume lines even a small inconstatnt leak can cause that. good luck.
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