4.7 Engine High RPM Start-up - JeepForum.com
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post #1 of 6 Old 07-04-2009, 05:20 PM Thread Starter
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2001 WJ 
Join Date: Apr 2009
Location: Dayton, Ohio
Posts: 464
4.7 Engine High RPM Start-up

Do any other WJ owners notice their WJs have weird start-up RPMs or is it just mine? When I first got it, I'd start it and it'd go to about 1,000 for a second and settle into idle. Then it went to 1,500 and settles into idle. Still fine, but now it's going to 2,000/2,100 before settling down. Anybody else have this problem? Is it even a problem or am I being a hypochondriac of sorts?


2001 Grand Cherokee Limited
2002 BMW 530i
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post #2 of 6 Old 07-05-2009, 09:30 PM
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2000 WJ 
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IAC thing my gc would jump up to 2300 every time I started up my jeep bought this from autopartswarehouse.com and every start now only revs to 1400 and then goes to Idle.

35" BFG KM2 6.5 x 5.5 IRO springs HC longarms, 242 swap, 40 series, custom dis., Hellas, Custom front bumper
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post #3 of 6 Old 07-06-2009, 12:00 AM
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Look at this thread...


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post #4 of 6 Old 12-23-2009, 02:33 PM
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2000 WJ 
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jeep 2000 4.7 rpm jumping

on my gc 4.7 the rpm's jump up and down all the time (in drive or in park) does anyone kn ow what is causing this? some days it works fine though so i dont know where to look.
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post #5 of 6 Old 05-14-2013, 08:00 PM
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I had the same problem on my 2000 jgc 4.7L with 115k. It would start up at 2500 rpm then slowly drop to 1900 and then swing right back to 2500. It would settle down after getting warm, but even warm would start up at 2500.
I fixed mine today, it was the IAC stepper. I just took it out and cleaned it with some mass airflow sensor cleaner and a rag. There was a lot of carbon build up on the tip, so a little elbow grease and it cleaned up pretty good. I also cleaned the the inner side of the throtle body where this thing was mounted.
After putting it all back together. It fired up at 1500rpm and quickly down to idle around 1100rpm.. nice!!
The whole job took about 30 minutes..
Tools required: flat head screwdriver, 10 mm socket, 3/8 or 1/4 wratchet with 3in extenion, and a torques bit, i didnt look at the size, but it was on the smaller side t25? Ill check and repost..
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post #6 of 6 Old 05-15-2013, 11:16 AM
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1997 ZJ 
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Still high. Bet you have a vacuum leak.

'97 zj 5.2, some stuff, some other suff, and some things that even work sometimes.

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