Rockfrog Posted October 5, 2014 Share Posted October 5, 2014 OK, so what we have here is not the usual high idle thread. I've completed the HO head swap, used a 99+ intake, 94 throttle body, 92 head and exhaust. Used the Renix TPS, and Renix IAC. Read somewhere a while back to use the renix IAC with the HO throttle body. Got her fired up and she sounds great, but idle is at 1500rpm now. No vacuum leaks, good seal on intake and TB. The HO IAC looked longer (on the inside) and I am thinking that's where my problem lies ... Anyone able to confirm? I should be able to grab a used HO IAC tomorrow, but just wanted to check here and hopefully move onto other issues .... Like getting the front axle attached. Anyone? Thanks in advance. Link to comment Share on other sites More sharing options...
88ComancheMitch Posted October 5, 2014 Share Posted October 5, 2014 Unplug the temp sensor and see if it fixes anything. I had that problem. What did you do for your tps? Link to comment Share on other sites More sharing options...
HOrnbrod Posted October 5, 2014 Share Posted October 5, 2014 If the HO IAC doesn't fix it (I think it will), you can set your idle using the set screw in the pic below. I had to tweak mine a bit when I installed a new 62mm bored throttle body recently. Link to comment Share on other sites More sharing options...
Rockfrog Posted October 5, 2014 Author Share Posted October 5, 2014 Picked up and HO IAC today when I was down Island (island cup 2014 4x4 event) This is how my tps is mounted, just got home have yet to install it. More details in my build thread. Link to comment Share on other sites More sharing options...
Rockfrog Posted October 7, 2014 Author Share Posted October 7, 2014 Well swapped in a 94 IAC, it idled at 700 for a few seconds then stuck at 1250 now, so bit better. The IAC housing looks bent a bit so I'll try swapping it and the housing again. I can live with it for now, and worry about it after she's on the road again. Unplugged the ect and saw no change. Hopefully it's not another dying tps again (that's what my last high idle was). Ahhh .... The never ending joys of Jeep. Link to comment Share on other sites More sharing options...
Rockfrog Posted October 8, 2014 Author Share Posted October 8, 2014 Another HO IAC later and we have a nice 600rpm idle. The first HO IAC was a dud it would seem. I also tried a renix IAC with a HO Pintle on it .... But for got to hook up the ballast resistor and thought it was a no go. Didn't realize my mistake until the third HO IAC was on. I'll try it again at a later date. As of right now she's purring like a kitten ... A happy 4.0 is a beautiful sound. I'll snap a picture of the various IAC's it looks like the renix one with an HO tip should work as well, and give better wire plug angle to boot. Link to comment Share on other sites More sharing options...
Rockfrog Posted October 11, 2014 Author Share Posted October 11, 2014 So it was idling at 1000-1200 again after a 250km highway run... Is it possible that I created a vacuum leak when I plumbed the EVAP cannister to manifold vacuum instead of to the air inlet just post filter? Was just thinking of how I set it up and that came to mind. Probably going to look for a new cannister from something at the JY with a smaller profile if I can and move it to the empty spot under the air filter making room for an HO filter adapter and a less messy (compared to Renix) oil change. Currently the purge line is run into the forward vacuum fitting on the back of the intake manifold. Thinking that may have been a mistake. Easy enough the check on the way home Wednesday I guess. Link to comment Share on other sites More sharing options...
Rockfrog Posted October 15, 2014 Author Share Posted October 15, 2014 Anyone think the placement of the EVAP hose maynbe my high idle issue? Out on the water at work right now but i head back to land and the MJ tomorrow afternoon. Was looking at some stock vacuum drawings and the EVAP was supposed to go to the airbox before the throttle body, not the manifold like I added it. Almost wondering if I might repurpose the egr vacuum solenoid to use as a purge valve? Even though the egr system is no longer in use due to the 99 intake manifold, it should still open up at WOT no? Would that be a good time to introduce fuel vapors? Link to comment Share on other sites More sharing options...
HOrnbrod Posted October 15, 2014 Share Posted October 15, 2014 Image Not Found Try sucking on the vacuum IN port with your mouth and a piece of hose to make sure the canister is not open and leaking internally. Link to comment Share on other sites More sharing options...
Rockfrog Posted October 15, 2014 Author Share Posted October 15, 2014 Mine is not like that one, that would be a better one. Mine has the vapor in from tank, and another originally hooked to the intake airbox. No vacuum motor/valve on top at all. Has a carb line (but it's plugged off). Gonna just unplug the manifold line and cap it for return trip home and see what happens. Is that the newer Chryco replacement? Mine says AMC on it. Link to comment Share on other sites More sharing options...
HOrnbrod Posted October 15, 2014 Share Posted October 15, 2014 Then you probably have this one below? And yes, they started using these around the late 80's and are all you can get now (except at the yard). Just last week I found the solution to a high idle problem (~1200 RPM) on my 91. Turned out to be a split short rubber hose that connected the vacuum check valve to the hard plastic line going to the intake manifold. It idles now nice much smoother @ 800 RPM. Image Not Found Link to comment Share on other sites More sharing options...
Rockfrog Posted October 15, 2014 Author Share Posted October 15, 2014 That's the one, and I have the airbox line going to the manifold ... Probably means I found my high idle issue ... Crossing fingers. Link to comment Share on other sites More sharing options...
Rockfrog Posted October 16, 2014 Author Share Posted October 16, 2014 Capped off the vacuum port and idle is back down. Now I have an exhaust tick, yay ... Probably a warped manifold. Link to comment Share on other sites More sharing options...
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