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Discussion Starter · #1 ·
There are many threads about this but none that are recent. Rather than bring one back from the dead that may or may not resemble my issue I'd like to just state my business and see if anyone knows whats going on.

After seafoaming my engine I had to immediately turn around and donate it to my aunt for 3 weeks. No the spark plugs were not changed like everyone recommends after SF'ing. Fast forward I get it back. Immediately change the Oil, Distro Cap, Rotor, Spark Plugs, Wires, and respray the K&N Air Filter.

Good to go now right? Apparently not. About 2 weeks later I notice the Jeep Rev'ing up to near 3,000 RPM the moment I start the ignition. Scarring the bejeezus out of me every time and waking up the neighborhood. (Not all bad because one neighbor decides to rev his bike All morning every weekend at about 7am just to hear it growl so fair is fair right?)

I can deal with that, however lately I've noticed while driving the Jeep wants me to go faster. It will rev up all on its own and start taking me from cruising up to a Yield or Stop at 15mph to 25mph or higher until I hit the breaks or the pedals. This truly scares me. How much longer until I think i'm slowing down and end up hitting someone?

My friend said to check the throttle cable. The only cable I know of is the spring that is attached to the throttle body. I mean theres tension there but thats how it was when I got the jeep. Should I WD-40 the spring? Or is there another Cable he is probably referring to?

Tonight I will unplug the battery, recheck all the vacuum lines and air filter latches. I'll even take apart the sensors attached to the throttle body and wipe the insides again but do you all have any experience with something like this?
 

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Discussion Starter · #3 ·
first, check that the TB is closed all the way
second, look for a vacuum leak
I will check again when I get home. A precursor question, if I find the TB is slightly open. Is it safe to assume that is because where ever I reattached the spring cord is too far, causing the TB to stay open slightly?
I am unsure where else this cord is to be hung, I will take pictures when I am home but perhaps someone has a photo of proper TB cable suspension?
 

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If not something physically hanging up your throttle cable, then I would put good money on your IAC valve sticking open. The high idle at start up is a clue to me that the IAC may be malfunctioning. If so, it could be letting too much air in at the wrong time and contributing to high rpm. I had somehting similar happen to me and a new OEM IAC valve and about 5 minutes to install it and I was good to go.

Just a thought. No harm in checking it out. Search "IAC" or my member name and you will get many posts on this including how to change it out, etc.
 

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Discussion Starter · #5 ·
Thanks mFarr, where did you find your part. I did a quick search online and found some from $12-$14 and some from $79-$105!
 

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On these sensors at the throttle body: only use OEM. No parts store sensors. The AutoZone IAC and TPS ones fail really quickly. Go OEM when getting critical parts; go aftermarket on no critical stuff and mods.

If you cleaned the IAC and you rotated the plunger sleeve you could have broken it. They are actually pretty fragile in this regard. So a malfunction after a cleaning is not uncommon.

[Regarding my above OEM comments: The TPS is not really serviceable and should be replaced when it starts to fail. The IAC, however, can be serviced to a certain extent. This is good because the OEM unit costs a lot from the dealer. But if you indeed damaged it then suck it up and hit the parts counter at your local dealership. You can get it slightly cheaper from a place like wermopar.com, but there is shipping costs and time to factor in.]
 

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As Holton says, buy the OEM unit. Autozone and the like will just fail in a few months if they work at all out the box. I know this from personal experience.

The OEM runs $80 or $90 at the dealer if they are not robbers, but I have found OEM units on ebay for $60 or so if you look around. Downside is waiting for the part on the mail.
 

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Discussion Starter · #9 ·
Thanks gang, I received my part today from Advanced Auto Parts. As you said I should have gone OEM but This one was $70 and identical to what I took out so I figured why not.



The shorter IAC is what came in today. I was a bit worried that the lengths vary but she starts up all the same. Should I be worried that the part I removed was silver (minus the rust spots) and the new part appears to be brass.

Suffice to say it did not change the issue of the jeep accelerating on its own. I think it may be the Throttle Cable perhaps? But I cannot find the cable on the engine side of the firewall to inspect if it is getting hung up on something.
 

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My bet is on nothing more than a vacuum leak and not from anything to do with the throttle cable.

Has the intake manifold ever been off?
 

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Sorry I did not mean to lead you down the wrong road and spend money by bringing up the IAC. At least you can rule it out now (and unfortunately replacing the part is often the only way for us weekend mechanics). The pindle moves in and out under control from the Jeep's computer, so don't worry about the length. A small pindle will work as well as a long pindle as I always tell my girlfriend. Also brass or other metal not too important I would guess.

If the IAC swap had no effect, I recommend you put the OEM back in, and if you can;t return the part you bought, just keep the aftermarket part in your garage just in case you need it someday. Even the OEM IAC will fail eventually.

With the IAC out of the way as a cause, I do then think you must have a vacuum leak if you can confirm that the throttle cable is not hanging up. Jerry is right about 100% of the time on these things, so I would go with what he said. I have never met the man but he has helped me out with his posts more times than I can count (thanks Jerry!).

The throttle cable really does not have many places to hang up. Check that it is routed and moves freely. Maybe yours is different but on my 99, it sort of does a half loop around the passenger side of the valve cover and then crosses over the valve cover through little spacers. There is some opportunity for a frayed or otherwise corroded cable to maybe get hung up inside the cable cover. That could cause some binding at speed. Not sure if those cables can be lubed. I never had the issue so it has not been touched on mine. After that I am stumped.
 

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Discussion Starter · #12 ·
My bet is on nothing more than a vacuum leak and not from anything to do with the throttle cable.

Has the intake manifold ever been off?
I suppose. I mean I take off part of it that leads to the Throttle Body when I clean that, I take off part of the other end when I soak the air filter. Vacuum leaks are a biotch to snuff out.

I think you may be right though. When I first started noticing this problem I checked the air filter, I had only put two latches on properly. I snapped down the other four or so and the problem seemingly disappeared. But as you all know its back now.

I will swap the IAC's again and attempt a return, but I kind of want to keep it near by so if they give me some pushback because I used it I won't fight. No worries man. It was either this or give it to my mechanic. Which I am about to do. I still need to trouble shoot the wiper's :-/
 

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Check the throttle body to be sure it isn't sticking, look for vacuum leaks, and check the IAC. I have a feeling the IAC is bad.
 

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Get a can of carb cleaner and spray around all the vacuum lines.
You will notice a increase in idle when you hit the leak.

Having the latches not locked down will not cause this issue.

Throttle position sensor?
 

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Discussion Starter · #15 ·
Get a can of carb cleaner and spray around all the vacuum lines.
You will notice a increase in idle when you hit the leak.

Having the latches not locked down will not cause this issue.

Throttle position sensor?
Was unaware of this little test. I will try that now. Thank you. If it is the TPS hopefully thats not a $75 part.
 

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Its old school.

Tps is under $50
But check for leaks first.

To verify the leak test works just take the vac Line off next to the throttle body (the one that provides vac to heat/air and cruise) and spray in that general area and you will see.
 

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Discussion Starter · #17 ·
Did the test, the rpms did not increase but I heard them bog down when spraying the line from the PCV elbow to the manifold.



ForumRunner_20140525_120844.jpg

I duct taped it as I needed the jeep today, and duct tapes main purpose is to block air in your heading ducts.
This fixed nothing. In fact on my trip to the park today the issue got worse. My only means of NOT accelerating is throwing it in neutral.

I'm going to call my mechanic tonight :-/
 

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Discussion Starter · #18 ·
I was told to try a few more things by my guy before bringing it to him. I looked online and am going to attempt to see if perhaps I have been hanging my Throttle Spring incorrectly.



You'll see here its hung facing Up, I believe I have been hanging mine facing down. (If it was this god damned simple I am going to just chug a bottle of Fireball).

Also I have read that a lot of people experience High Idle issues in turn with a missing "intake Manifold Bolt".



Now I have found the image above, but I am unsure where this is precisely. Any tips on where I may find it on my 2.5L engine are appreciated, images welcome.
Reading tells me its under the engine, I hope I can find it and I hope that perhaps its this simple as replacing a missing bolt.

I have considered getting a new TPS. They are $70 from Advanced (BWD part) or $40 from Autozone (Duralast). I must admit i'm leaning towards the cheaper one because I may still need to buy a whole knew Wiper Motor or Wiper switch, but another problem for another day.
 

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The manifold is where the exhaust goes into the engine. Follow the exhaust and you will find it. It's not the tps sensor.
 
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