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Author Topic: Weird revving  (Read 2113 times)

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Nicks92jeeper

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Weird revving
« on: November 27, 2011, 07:28:50 AM »
So the last week or so I notice that when I take my foot off the gas and push in the clutch my jeep actually revs up from 2,000 to about 3,000 rpm. Anyone know what might be causing this? It is getting colder out now and I do have a cold air intake on the jeep so I was thinking maybe the air is too cold?
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Offline sharpxmen

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Re: Weird revving
« Reply #1 on: November 27, 2011, 07:35:52 AM »
Quote from: Nicks92jeeper on November 27, 2011, 07:28:50 AM
It is getting colder out now and I do have a cold air intake on the jeep so I was thinking maybe the air is too cold?
nope, the idle is based on engine temp and not air temperature. do you have the 2.5L IAC motor and housing on your 4.0 t/b? if you look at your butterfly thru the t/b in the light how much space is in between - if i remember correctly you sanded out the t/b (or I'm mixing this with someone else doing it), i think too much space between the 2 would cause that behaviour.
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'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
Latest: Corbeau BajaRS heated seats :dance: keeping warm the rear end

Offline aka-justin

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Re: Weird revving
« Reply #2 on: November 27, 2011, 12:25:35 PM »
Check for any vacuum leaks? That's sure to cause your idle to race. Don't know about 3 grand worth, but it will jump up.
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[1995 YJ 2.5L with 4" lift on 31" KM2 - Sold] 1995yj
[2003 TJ Rubicon 4.0L with 4" lift on 35" Wrangler M/T - Sold]
To be continued...
--Justin

Torch_Ind

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Re: Weird revving
« Reply #3 on: November 27, 2011, 12:38:36 PM »
Quote from: 1995yj on November 27, 2011, 12:25:35 PM
Check for any vacuum leaks? That's sure to cause your idle to race. Don't know about 3 grand worth, but it will jump up.

yup I would check idle leaks

did you put a bigger tb on it and not use the 2.5L iac?
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Nicks92jeeper

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Re: Weird revving
« Reply #4 on: November 27, 2011, 03:23:55 PM »
I did the 4.0 Tb swap about a year ago and it has been fine since. I did bore the TB out a bit but was careful to not get too close to the butterfly. Just opened it up a little bit more then what it was before. I do have a cold air intake on it and was considering going back to stock with a high flow air filter in it. Could the cold air intake cause that problem or perhaps a sensor is going out?
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Torch_Ind

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Re: Weird revving
« Reply #5 on: November 27, 2011, 05:12:48 PM »
Quote from: Nicks92jeeper on November 27, 2011, 03:23:55 PM
I did the 4.0 Tb swap about a year ago and it has been fine since. I did bore the TB out a bit but was careful to not get too close to the butterfly. Just opened it up a little bit more then what it was before. I do have a cold air intake on it and was considering going back to stock with a high flow air filter in it. Could the cold air intake cause that problem or perhaps a sensor is going out?

I don't see how cause you can run it with nothing on it if you wanted or even just a filter on the throttle body wouldn't cause this problem

has this problem started since you bored the tb your self?
« Last Edit: November 27, 2011, 05:13:56 PM by Torch_Ind »
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Nicks92jeeper

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Re: Weird revving
« Reply #6 on: November 27, 2011, 08:04:34 PM »
The throttle body was done months ago and nothing really changed except the weather. Unless a hose fell off somewhere which is possible. Just thought it was a weird revving like the throttle was going by itself even though the clutch was pushed in.
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Torch_Ind

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Re: Weird revving
« Reply #7 on: November 27, 2011, 08:13:48 PM »
Quote from: Nicks92jeeper on November 27, 2011, 08:04:34 PM
The throttle body was done months ago and nothing really changed except the weather. Unless a hose fell off somewhere which is possible. Just thought it was a weird revving like the throttle was going by itself even though the clutch was pushed in.

is your throttle dirty and sticking? and check for vacuum leaks..
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Offline grumpygy

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Re: Weird revving
« Reply #8 on: November 27, 2011, 10:13:08 PM »
Really could be a hose causing a vacuum leak.
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94 YJ, Cool Air intake, 19lb Inj, 4.0 Throttlebody with spacer,  31/10.50/15's

Offline dwtaylorpdx

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Re: Weird revving
« Reply #9 on: November 27, 2011, 11:35:10 PM »
Sounds like a gummed IAC valve, I spray a shot of carb cleaner though the idle gap each oil change.

Dave
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94 YJ - 2.5 Hesco Cam B&B Ported - AX5 Trans w/Centerforce Dual Friction Clutch - 4" Rough Country Lift W/Skyjacker Shocks - D44 Rear/ARB - D30/ARB - ARB Compressor - Warn M8000 in Custom Bumper - Reunell Rear Bumper - Metalcloak 6" Body Armor Kit - Tuffy Console - 265x85-16 Tires - 2M Radio

Nicks92jeeper

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Re: Weird revving
« Reply #10 on: December 16, 2011, 11:37:54 PM »
Been a while since I have been on but the revving continued to get worse. I couldn't find any leaks or anything but last week when I was driving, I pushed in the clutch and as it was revving weirdly I quickly put my foot under the gas pedal and lifted up. The rev went away and all was fine but it continually sticks. Any ideas on what might be sticking whether it is the pedal or something else.
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Offline sharpxmen

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Re: Weird revving
« Reply #11 on: December 17, 2011, 08:07:07 AM »
Quote from: Nicks92jeeper on December 16, 2011, 11:37:54 PM
Been a while since I have been on but the revving continued to get worse. I couldn't find any leaks or anything but last week when I was driving, I pushed in the clutch and as it was revving weirdly I quickly put my foot under the gas pedal and lifted up. The rev went away and all was fine but it continually sticks. Any ideas on what might be sticking whether it is the pedal or something else.

it's probably the cable but you can check that easily, unhook the cable at the pedal and see if the pedal moves freely, if it does then it's the cable, if you feel it sticking then it's the pedal. I would check the carpet first though to make sure is not interfering
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'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
Latest: Corbeau BajaRS heated seats :dance: keeping warm the rear end

Offline grumpygy

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Re: Weird revving
« Reply #12 on: December 17, 2011, 12:17:17 PM »
How is the return spring on the throttle body.
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94 YJ, Cool Air intake, 19lb Inj, 4.0 Throttlebody with spacer,  31/10.50/15's

Nicks92jeeper

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Re: Weird revving
« Reply #13 on: December 18, 2011, 07:36:39 AM »
The return spring on the TB looks good. I will check the carpet first to see if that is in the way and go from there. Pry grease up the pedal to see if that is the problem since I am there. Should be a beautiful 56 degrees out today!!!
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Offline grumpygy

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Re: Weird revving
« Reply #14 on: December 18, 2011, 12:10:38 PM »
Quote from: Nicks92jeeper on December 18, 2011, 07:36:39 AM
The return spring on the TB looks good. I will check the carpet first to see if that is in the way and go from there. Pry grease up the pedal to see if that is the problem since I am there. Should be a beautiful 56 degrees out today!!!

43 here and I need to put on the new lights I have so I have a better Backup Lights on the jeep, then Fog lights on my truck  But that one I need to pull the airdam off to do that.
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94 YJ, Cool Air intake, 19lb Inj, 4.0 Throttlebody with spacer,  31/10.50/15's
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