702_MJ Posted March 19, 2009 Share Posted March 19, 2009 Ok, installed a different MAP sensor and a CTS and the truck runs great. But theres one thing that concerns me. It doesnt idle the same, around 500rpms maybe a little bit more or a little bit less, depends on what it feels like i guess. It starts, runs and drives fine, but the idle is just different and maybe I'm just paranoid. Whats your comanche's with 4.0L idle? Maybe something is wrong.........maybe something is going failing, or maybe its just cuz the MAP sensor :dunno: Link to comment Share on other sites More sharing options...
glundblad Posted March 19, 2009 Share Posted March 19, 2009 Mine has only 82k miles on it and does the exact same thing. Runs smooth as silk, like new in fact until it idles. It never dies but definately idles slower than it used to. I replaced the TPS and it didnt help. Cleaned it and so on. I gave up and in the next couple of weeks, I will be making a sizable donation to a Jeep dealer. I will be very curious to see if they find anything. :ack: Link to comment Share on other sites More sharing options...
Jerry Posted March 19, 2009 Share Posted March 19, 2009 Think yourself lucky you don't have a recalcitrant 2.8 with a carburettor! ;) It most definitely has a mind of its own :nuts: Sorry I can't be of more help with your OP :yes: Mine idles somewhere between 100 and 1500 rpm :thumbsup: Link to comment Share on other sites More sharing options...
Ed in North Ga. Posted March 19, 2009 Share Posted March 19, 2009 you`ll hear that 800 to 1000 rpm is normal idle- and it is. most all idle problems are traced to the IAC- clean that, if it works, its golden! then...theres a possible vacuum leak that throws everything out the window. 600 to 1000 or so, good- higher/lower bad. Link to comment Share on other sites More sharing options...
702_MJ Posted March 20, 2009 Author Share Posted March 20, 2009 Yeah mines got a mine of her own too. She won't stall but she gets to about 400rpms some times, and i don't know why. IAC is where i was gonna try first. Then the CPS, i don't know why, but might as well since I'm looking for the culprit. Then vacuum leak check, i know i broke the line on the rear PCV, by the way does anyone know where i can get a new one? Cuz it looks ghetto when theres just a piece of large hose and silicone holding the hose in the pcv fitting thing. i really hope its the first one, so far ive been lucky with first tries :thumbsup: Link to comment Share on other sites More sharing options...
Geonovast Posted March 20, 2009 Share Posted March 20, 2009 My 2.5 idles around 1100, 4.0 at 600ish. Both my Renix 4.0 XJs idled at 6-700. Link to comment Share on other sites More sharing options...
88XJSport Posted March 21, 2009 Share Posted March 21, 2009 My 88 4.0 idles like crap. It will idle about 700 or so, then drop down to about 500 and be rough, then jump back to 700 sometimes. I need to keep the defroster on to keep everything steady...I'm thinking its a vacuum issue that I'm too lazy to look into... Link to comment Share on other sites More sharing options...
Ed in North Ga. Posted March 22, 2009 Share Posted March 22, 2009 Yeah mines got a mine of her own too. She won't stall but she gets to about 400rpms some times, and i don't know why. IAC is where i was gonna try first. Then the CPS, i don't know why, but might as well since I'm looking for the culprit. Then vacuum leak check, i know i broke the line on the rear PCV, by the way does anyone know where i can get a new one? Cuz it looks ghetto when theres just a piece of large hose and silicone holding the hose in the pcv fitting thing. i really hope its the first one, so far ive been lucky with first tries :thumbsup: NAPA carries the entire vac kit on the top- sometimes they sell both together...sometimes front half/rear half. Mopar will sell it as well, and depending on the day, it can be 3 times as much as NAPAS, or half as much... spend wisely, shop for price. Link to comment Share on other sites More sharing options...
702_MJ Posted March 24, 2009 Author Share Posted March 24, 2009 i looked at everything its all good. Maybe thats just the replacement map sensor it did come off a fourbanger, but I'm gonna keep lookn. idk my jeep needs to be tore down and built back up again. She is crazy :nuts: , now i just need to get a different DD. Link to comment Share on other sites More sharing options...
TNT Posted March 24, 2009 Share Posted March 24, 2009 you`ll hear that 800 to 1000 rpm is normal idle- and it is.most all idle problems are traced to the IAC- clean that, if it works, its golden! then...theres a possible vacuum leak that throws everything out the window. 600 to 1000 or so, good- higher/lower bad. Clean the throttle body bore and plate too. A specfic amount of air is supposed to go past it at idle. When it gets dirty the idle gets lower. Link to comment Share on other sites More sharing options...
vaquaro Posted March 25, 2009 Share Posted March 25, 2009 you`ll hear that 800 to 1000 rpm is normal idle- and it is.most all idle problems are traced to the IAC- clean that, if it works, its golden! then...theres a possible vacuum leak that throws everything out the window. 600 to 1000 or so, good- higher/lower bad. :dunce: Please define IAC :dunno: Link to comment Share on other sites More sharing options...
Geonovast Posted March 25, 2009 Share Posted March 25, 2009 Idle Air Controller, it's what opens up the TB when it's idling. If it's gummed up, it won't work properly and the motor won't idle right. Link to comment Share on other sites More sharing options...
vaquaro Posted March 25, 2009 Share Posted March 25, 2009 Idle Air Controller, it's what opens up the TB when it's idling. If it's gummed up, it won't work properly and the motor won't idle right. Now I are smart .... :doh: ....Is that also refered to as a "throttle kicker motor " ? :hmm: Link to comment Share on other sites More sharing options...
BLHTAZ Posted March 25, 2009 Share Posted March 25, 2009 No, a throttle kicker motor was something used on some older vehicles that would increase the idle speed to accommodate the AC when turned on. It is referred to as an Idle Stepper Motor in some cases though. :cheers: Link to comment Share on other sites More sharing options...
vaquaro Posted March 25, 2009 Share Posted March 25, 2009 No, a throttle kicker motor was something used on some older vehicles that would increase the idle speed to accommodate the AC when turned on. It is referred to as an Idle Stepper Motor in some cases though. :cheers: Aaah....now I understand....It's better out here in the light ,Thanks -Gord :bowdown: Link to comment Share on other sites More sharing options...
ComancheKid45 Posted April 11, 2009 Share Posted April 11, 2009 I'm having a startup idle issue....when I 1st fire my truck up sometimes itll just peg itself about the 1500-2000rpm range for about 15-20 secs than come back to normal idle.....Ive cleaned the TB, cleaned the IAC and even replaced it with another IAC and the problem still is there. Sometimes itll just rev up hight on intional startup and come right back but other times itll stick reving fairly high for 15-30 secs. I don't have a tach so rpm #s are not 100% accurate but where else can i look for a possible solution? Link to comment Share on other sites More sharing options...
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