Throttle_Jockey Posted October 22, 2008 Share Posted October 22, 2008 My 4.0 renix has a high idle problem like the throttle is stuck but the cable and pedal is fine.It's high enough that it is causing me to have problems shifting gears I can't seem to figure it out and need some help. OH by the way thanks in advance Link to comment Share on other sites More sharing options...
Throttle_Jockey Posted October 22, 2008 Author Share Posted October 22, 2008 five views and nothing sure wish somone could help its pretty aggrevating to drive this thing in traffic like this :headpop: Link to comment Share on other sites More sharing options...
Pete M Posted October 22, 2008 Share Posted October 22, 2008 Could be a significant vacuum leak, a faulty IAC or a faulti TPS. I would start by popping off the air duct and cleaning out the throttle body area with Q-tips and an O2 sensor safe throttle body cleaner. Could be just built-up gunk in there. :cheers: Link to comment Share on other sites More sharing options...
BLHTAZ Posted October 22, 2008 Share Posted October 22, 2008 I just went through this nightmare. Mine was up to running at 3000 RPM. Here is the thread detailing what I went through... http://comancheclub.com/forums/viewtopic.php?t=12188 Ultimately, as you will see, my issue was a bad ground. The two most common idle issues are vacuum leaks and the IAC. The IAC has no self tests that I could find, but needs a special tool to test it so you just have to look down in the top of the throttle body while it is running to see if it is closing or not. You can also put a couple fingers over the air inlet hole to the IAC and see if it helps, but be careful as the vacuum at that point is very strong if the IAC is stuck open. I posted in the DIY forum about how to do the test on the TPS if you want to do that too. That is here... http://comancheclub.com/forums/viewtopic.php?t=12260 Link to comment Share on other sites More sharing options...
Throttle_Jockey Posted October 22, 2008 Author Share Posted October 22, 2008 thanks for the replies I read about the same problem on jeepforums and tone guy had the same issue and said that his intake manifold bolts were backing off so i tighteneed them up and still the same problem but I'm gonna check out your thread and Ill let you know how it comes out thanks again guys :cheers: Link to comment Share on other sites More sharing options...
BLHTAZ Posted October 22, 2008 Share Posted October 22, 2008 I have heard of the intake gasket being bad and causing this problem too, but it is a lot less likely than the IAC or a vacuum hose leak. I read that same thread over there when I was researching my problem :D :cheers: . Link to comment Share on other sites More sharing options...
Throttle_Jockey Posted October 23, 2008 Author Share Posted October 23, 2008 well I finally figured it out after reading blhtaz's thread I checked the ground and there was a problem there but not the cure for me so I cleaned the throttle body and the IAC and fired it up but the same thing was happening so I stuck my thumb over the port in the TB for the IAC and it idled fine then while looking around I realized that I forgot to plug the harness for the IAC back up,when I did it ran like a champ. It eats me up when I have a problem with this truck because I'm a mech. by trade and have built some pretty serious small block chevy's,and making harley's go fast is my number one hobby,but this is my first jeep and there's ahe new learning curve everyday with this thing but I'm not giving up it's a dying breed and it's up to us to keep it alive thanks a million to pete and blhtaz for your if I'm ever in either of you guy's neck of the woods I owe you a beer. Link to comment Share on other sites More sharing options...
BLHTAZ Posted October 23, 2008 Share Posted October 23, 2008 8) Glad th hear it. I have found the Renix system to be a bit of a challenge myself after being in the auto business for many years. These things are definitely a "new challenge". :D Link to comment Share on other sites More sharing options...
Throttle_Jockey Posted October 23, 2008 Author Share Posted October 23, 2008 Last night every thing worked fine then this morning on my way to work it started again I'm not sure what it is bvut when I put my finger over the IAC port from the top of the throttle body it runs fine so I'm guessing the IAC has gone south Link to comment Share on other sites More sharing options...
BLHTAZ Posted October 23, 2008 Share Posted October 23, 2008 When mine went bad...that's how I diagnosed it and that was prior to the other issue that I caused myself with the ground problem. When my original went bad, I could tap on it with a wrench when it was stuck open and it would close. Link to comment Share on other sites More sharing options...
Throttle_Jockey Posted October 23, 2008 Author Share Posted October 23, 2008 WWhat is the purpose of the IAC?Does it really have to be there or could the port in the TB be plugged off? Link to comment Share on other sites More sharing options...
BLHTAZ Posted October 23, 2008 Share Posted October 23, 2008 The IAC is what controls the idle and no, it will not operate correctly without it. I tried running mine with the IAC unplugged and while it did run, the idle was a little wierd...usually low and almost stalling...and the acceleration was not right either. I would imagine that the MPG would be way off as well, but I didn't run it that way long enough to go there ;) . I have a full FSM in a .zip file. It's for an '88, but it should still apply to what ever year yours is between '87 & '90 for the most part. If your email can receive a file that is about 17mb, PM me your email address and I will send it to you. It was quite helpful to me during my battle :cheers: . Link to comment Share on other sites More sharing options...
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