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Old 06-23-2011, 04:50 PM   #1
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Idle?

So yesterday I changed out my intake/exhaust manifold gasket and and also cleaned out the throttle body spacer and also gave the iac a good cleaning! Any be fore I did all this the idle would sit at 500rpm and now it is sitting at 1000 to 1100 rpm! It this a good idle speed for the 2.5 or did I screw something up? I did double check all the vacuum lines and they look great!

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Old 06-23-2011, 04:52 PM   #2
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I would say 500 would be low but 1000 is pretty close to good. I always thought around 800 was good but thats for a 4.0 idk if the 2.5 is diff.

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Old 06-23-2011, 06:25 PM   #3
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well maybe it change for the better than! maybe a couple 2.5 guys will chime in thanks for the imput golden!
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Old 06-23-2011, 08:54 PM   #4
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my 2.5 idles around 800, but the IAC is in need of a good cleaning.
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Old 06-23-2011, 10:52 PM   #5
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Quote:
Originally Posted by stykthyn
my 2.5 idles around 800, but the IAC is in need of a good cleaning.
When u clean the iac does the idle drop or rise most of the time!
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Old 06-24-2011, 08:36 AM   #6
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Never cleaned it before. I bought ita few months ago and it had a pretty nasty lope ate idle. New plugs/wires, and vacuum lines helped a lot, but its stll there. Iac is next on the list.
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Old 06-24-2011, 08:53 AM   #7
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What year is this? If it's an 87, here's a tip that might be useful.

Idle Speed Control (ISC) Motor Plunger

1. Remove air cleaner, turn off A/C (if equipped) and warm engine to normal operating
temperature. Connect tachometer negative lead to diagnostic connector terminal "D1-3" and positive lead to connector terminal "D1-1". See Fig. 1 . Turn ignition off. ISC plunger should fully extend.

2. With plunger extended, disconnect ISC motor electrical connector. Start engine. Engine idle speed should be 3300-3700 RPM. If not, turn plunger hex head to obtain 3500 RPM. See Figure 2.

3. To fully retract ISC motor, hold closed throttle switch plunger inward while opening throttle. Closed throttle switch plunger should not touch throttle lever when throttle is closed. If this occurs, check linkage and/or cable for binding.

4. Connect ISC motor connector. Turn ignition off for 10 seconds. ISC motor should fully extend. Restart engine. Engine speed should momentarily be about 3500 RPM and return to idle speed. Turn ignition off and disconnect tachometer. Apply sealant to adjustment screw threads. Install air cleaner.

Holding plunger inward may create an intermittent trouble code in ECU memory. To clear ECU memory, turn ignition off and disconnect negative battery cable for 10 seconds.





If you don't have an 87, I can see what I can find for it. But I'd imagine a 4-banger should idle around 800-900 RPM's.
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Old 06-24-2011, 08:54 AM   #8
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My 2.5 idles at 1000. That's about right for the 2.5
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Old 06-24-2011, 10:13 AM   #9
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Idle should be around 600 rpm...
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Old 06-24-2011, 11:26 AM   #10
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Quote:
Originally Posted by stykthyn View Post
Never cleaned it before. I bought ita few months ago and it had a pretty nasty lope ate idle. New plugs/wires, and vacuum lines helped a lot, but its stll there. Iac is next on the list.
where did you find new vac lines?
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Old 06-24-2011, 11:30 AM   #11
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^Just buy the lines from a parts store, autozone, advance etc.......It's a universal line you get according to the size you need and then cut it and swap it out for the old stuff.
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Old 06-24-2011, 01:02 PM   #12
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^Just buy the lines from a parts store, autozone, advance etc.......It's a universal line you get according to the size you need and then cut it and swap it out for the old stuff.
Exactly. Does anyone know if there is an idle reset sequence? I know with fords you unplug the battery and the IAC. Clear the computer, hook the battery back up and start the vehicle. Once it has a stable idle you cut the car off and plug the iac back in. Does the jeep have same procedure?
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Old 06-24-2011, 05:55 PM   #13
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So it sounds like I might need a new iac then!
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Old 06-24-2011, 05:58 PM   #14
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Reset the ecu? Mine was a little erratic after cleaning. Pulled the neg over night, good to go
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Old 06-24-2011, 09:21 PM   #15
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Count yourself lucky, I had a low idle around 500, replaced the IAC and TPS, now its down to 400. The whole reason I replaced them was to increase it, I'm still trying to figure it out. Sounds like yours has gone the right way.
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Old 06-24-2011, 09:24 PM   #16
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Quote:
Originally Posted by BillyLA
Count yourself lucky, I had a low idle around 500, replaced the IAC and TPS, now its down to 400. The whole reason I replaced them was to increase it, I'm still trying to figure it out. Sounds like yours has gone the right way.
Yeah me too
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Old 06-24-2011, 09:37 PM   #17
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Count yourself lucky, I had a low idle around 500, replaced the IAC and TPS, now its down to 400. The whole reason I replaced them was to increase it, I'm still trying to figure it out. Sounds like yours has gone the right way.
not sure if the tps on a jeep is adjustable or not as I havent been around them that long, but is sounds like its out of adjustment. a quick google search came up with this. not sure if it will apply, but worth a shot.

Turn the ignition switch in the Jeep to the "On" position but do not start the engine. Locate the connector on the back of the throttle position sensor but do not unplug it.



2 Locate the markings on the connector that indicate the positions. Each is marked with a letter starting with A and running through D. Insert the black test lead from your voltmeter into the back of terminal D, being careful not to damage the wire or terminal.

3 Insert the red test lead from your voltmeter into the back of terminal A. Note the reading on the voltmeter: this is the input voltage. Make sure that the throttle plate is completely closed when you take this reading.

4 Remove the red test lead from terminal A and insert it into the back of terminal B. Note the reading on your voltmeter: this is the output voltage of your TPS.


5 Divide the output voltage reading by the input voltage reading. The result should be between .825 and .835 (.830 is optimum). If yours is not in this range, adjust the TPS by loosening the Torx head retaining screws and turning the TPS slightly then repeat the test until it falls into this range.

6 Test-run the engine and drive the Jeep to make sure the TPS is functioning properly.
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Old 06-24-2011, 09:51 PM   #18
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yeah it could be, it did come with instructions on how to adjust but I haven't got round to it just yet. I think mine is also related to the fuel pump starting to fail because when I'm on the freeway, and most other roads actually, the engine pulses in a consistent pattern.

@zte87 - I would double check your vacuum lines just to be sure, I had a vacuum leak for a while and turned out to be the nipple on the throttle body had split in half and was letting air in, that was before my idle went to 500.
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Old 06-24-2011, 10:23 PM   #19
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My 95 2.5 idles 600-800. There is a small notch on the rpm indicator that is around the 400 a minute range. When it was new that's where it usually just purred along.
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Old 06-24-2011, 10:25 PM   #20
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so 400 is good?
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Old 06-25-2011, 11:41 PM   #21
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So I can't find any leaks but when I start the rig it is down around 700 but after driveing it it goes back up to 1100 what ealse can cause this? I tryed leaving the battery unhook over night but that diet help!
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Old 06-26-2011, 08:17 AM   #22
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You didn't mess witth the tps did you?
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Old 06-26-2011, 10:58 AM   #23
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I clean out the tb really good but Didt take the tps of while doing does it screw with it when u clean the tb really well?
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Old 06-26-2011, 02:10 PM   #24
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It shouldnt
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Old 07-02-2011, 04:27 PM   #25
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Well I am getting a code 24 and 25 so I guess it's time for a new tps and iac sensor!

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