Cleaning IAC and Throttle body write up (for dummies) - Page 13 - JeepForum.com
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Unread 05-20-2012, 09:28 PM   #181
SlackJaw
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Quote:
Originally Posted by flying_bosun

You got it out clean, yeah? Match it with a quality Phillips or Allen head fastener from the hardware store and be done, IMO. It could be tough to source the torx head type, except through a dealer.
Heh...not yet but it looks like it'll come out okay when I get around to it. Some allen heads will be perfect. Thanks!

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Unread 05-24-2012, 02:33 PM   #182
Aristotle113
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Update:

So after cleaning the IAC and the RPM's running insanely high, my check engine light finally came on. I went on down to Auto Zone and had them run the diagnostic for me, and it showed the code for the IAC: P0505. When I got home, I ordered a new one and it arrived, so I went about installing it. Problem: despite being the same part number, the terminals are different. This one had rounder prongs and wouldn't fit.

Okay, back to the drawing board. I reinstalled the original and ordered another one, this one with blade style terminals. It arrives, and I take a comparison picture with the first replacement that I ordered:


Left side is rounder prong, right side is "blade style."

So I uninstall (unstall?) the original again, but this time I compare it to the new replacement:


Left side is "blade style," right side is original.


And that sonuvagun has bigger prongs, too. (You guys can mock me for getting parts off of ebay, now).

But by now, I'm determined, so I finagle it and work it and get it partially plugged in. I hook everything back up, and RPMs are high again. So I check for vacuum leaks, but I can't find any (yay?), and I keep the IAC plugged in but disconnected from the TB to make sure it is working, and it is, then I repeat with the original, and it's working, too. At this point, I'm just frustrated, so I spray the original and wipe off the little bit of gunk that has already been deposited since I cleaned it. I disconnect the battery, touch the cables together (I read somewhere that this discharges the capacitor and lets the computer reset (or reset easier, I forget), reconnect the original, and wait about an hour while I install the hood deflector, then reconnect the battery.

I'll be damned if it doesn't work like a charm now. Runs smooth, idles where it's supposed to, and I just had a great test drive - all with the original IAC. I don't know what I did. Maybe the 20 minutes I let the battery sit last time wasn't good enough, maybe touching the cables together helped, maybe I just tightened everything a little tighter. In any case, I have no idea, but I thought this would help in case anyone else runs into the same issues I did.
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Unread 05-25-2012, 06:24 PM   #183
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And there goes my excitement. Engine light came back on and the RPMs are low again.
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Unread 06-04-2012, 11:33 PM   #184
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Where are u all idling at? I'm at 1,000.

P2074 also but everything seems nice and snug.

***EDIT***

I cleaned my throttle body based upon rough idling and a dead spot when hitting around 50mph. The gas pedal would be pushed to the floor with no response. Seemed to stay in 3rd gear instead of transitioning to 4th.

Since cleaning the throttle body and IAC I first received the p2074 code. I began driving the Jeep with the pulsating RPM's. When hitting 40-50mph and the egine was under load (climbing a incline) the Jeep would just suddenly die. I could pull the Jeep over wait a minute or so and the Jeep would start right up.So, I decided to check all of my connections and look for a vaccum leak as well. This resulted in nothing being found.

When reassembling everything the Jeep became hard to start. I had to push the throttle to get the Jeep to start and once started the RPM's jumped to 2,000 and stayed. Also when the Jeep was put in to gear the Jeep wanted to surge. I then recieved P0123 and P0068 codes.

So, I ordered a new TPS and installed it. I noticed the new clock spring would rotate slightly to the left or right to line up the screws for placement. However, the old TPS would only rotate in one direction.

Upon installation, the Jeep immediately started up and hovered @ 1,000 RPMs for a short whil and then idled down. No pulsating, no dead spot in the throttle and no surging.

I ordered the TPS through Federated Auto "standard ignition" brand TPS. I've read that the Advance auto and auto zone TPS's caused problems after the install. So, make your own decision on the type of TPS you choose to install.................
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Unread 08-01-2012, 04:45 PM   #185
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did it today, great directions thanks
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Unread 08-04-2012, 05:41 PM   #186
AMD_GAMER
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I have been having problems with high idle during start-up 1400-1700 RPM. Also, sometimes if I am on the highway and let off the gas, the RPM's drops and then goes right back up even though I am only coasting. I figured the IAC and TPS were good places to start.

However, I cannot get the torx 15 heads off. They are so tight. I hate to keep trying to get them off and strip the heads. Any ideas?

Dave
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Unread 08-15-2012, 04:00 PM   #187
NorthwestTJ
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Quote:
Originally Posted by AMD_GAMER
I have been having problems with high idle during start-up 1400-1700 RPM. Also, sometimes if I am on the highway and let off the gas, the RPM's drops and then goes right back up even though I am only coasting. I figured the IAC and TPS were good places to start.

However, I cannot get the torx 15 heads off. They are so tight. I hate to keep trying to get them off and strip the heads. Any ideas?

Dave
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Unread 08-20-2012, 08:52 AM   #188
Mboelts
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I had the same thing after cleaning mine yesterday. Didn't completely pull it apart to clean the IAC area but did soak it down and wiped it out pretty good. The IAC was very dirty and the throttle blade was dirty too so pulled it all and made it look like new. Then once reinstalled idle went way up to about 3 k then backed down to 1500-1700. Shut it down then pulled the power cable from the battery and held it to the neg side for a couple of minutes to reset the ECU. But still have a start up idle of around 1500 then drops to around 1k. Going to try a couple of cold starts over the next few days to see if there is any change. If not guess its new IAC time since I am getting NO codes. Amazing how you can clean something and it makes the jeep behave completely different. It is like the engineers just knew it was going to get dirty and programmed the system to run with it that way!
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Unread 08-26-2012, 08:18 AM   #189
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Ok after a week of high idle decided to start with the TPS and replaced it with a crown replacement. Issue solved. Somehow the original tps either was going bad. Or pulling it from the tb to clean the iac housing caused it to go bad, either way the jeep is back to normal idle and is much smoother from cleaning the tb.
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Unread 08-27-2012, 06:07 AM   #190
mgrimes554
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Mine kept throwing the P0121 code and hesitating at idle, misfiring a little bit in the lower RPM range. Took a can of Throttle Body cleaner and cleaned the throttle body, off of the Jeep, with rags, Q-Tips, etc. I couldn't believe how clean the intake manifold was, with the TB being so dirty. Took off the TPS and cleaned it as best I could. When I got it all back together, I ran a third of a can of Seafoam through the engine via the brake booster vacuum hose ,put a third in the gas tank and the last bit in the crankcase. Runs like a champ now. No hesitation, no codes, just good clean squirrels. :-)
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Unread 08-31-2012, 10:44 AM   #191
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Cleaned my IAC yesterday and my jeep idles so much smoother now! Just need to get a new gasket and I'm gonna clean the throttle body ASAP. Thanks for the write up
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Unread 09-15-2012, 09:10 PM   #192
atty
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Not to beat an old thread to death, but this apparently is a problem that is common and affecting a wide number of Jeeps. I certainly want to thank all those who have contributed, and I don't want anyone to think that just because of the age of the thread that the topic is dead. This thread has been highly informative and highly relevant to today.

2000 Jeep Grand Cherokee 4.7L 68K that has spent most of its life in the garage, but on a road trip to Ohio I started getting erratic idle, surging up, back down, and especially high on cold start in the morning. My pea brain set out to try to determine what cause could possibly be related to age, or immediate road trip. This thread nailed it.

While I still think of this old girl as "new", I realize that it is finally showing age as well as a few miles suddenly added. Anyway, I just pulled the IAC and was amazed at the carbon built up on the pintle as well as the female side. Cleaned everything up with a shot of throttle cleaner, and all is well.
Idle is smooth, and all is back to normal.

I thank everyone for the posts.
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Unread 11-01-2012, 06:03 PM   #193
mpdust
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Awesome write-up

First time do-it-yourselfer here. This write up was perfect. The process couldn't have went smoother. After I cleaned and re-installed everything, my Jeep ran so much better. Thanks again! Well done.
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Unread 11-07-2012, 09:09 AM   #194
Aristotle113
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Just an update. As it turned out, the computer in mine was shot, so it had to be replaced. Of course, they were on national back order, so my mechanic had to go to some lengths to track one down. Runs great now - nice and smooth.

Moral if the story: if cleaning the IAC doesn't help, check the computer.
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Unread 12-27-2012, 11:00 AM   #195
Sgt_turp
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I cleaned my iac sensor and my wrangler doesnt stall anymore, but I couldn't get the throttle position sensor off to clean it, I broke 2 torx bits on it.
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