88whitemanche Posted December 10, 2013 Share Posted December 10, 2013 What's up guys I have an 88 2.5 ax5 4x4 I've been having really crazy idle...by what I mean crazy I mean that there's never a set idle this truck has since I've been driving it the past 2 years...one moment it's at normal idle(600-700 rpms) then bogs down to 100-300 rpms...I've already done the ground refreshing for this truck, the refreshing of the c101, and I haven't checked vacuum lines since I last changes them last year...I will do a brake fluid test to check for a vacuum leaks but is there any more other ideas this would lead to this crazy idling? Link to comment Share on other sites More sharing options...
TheDirtyJeep401 Posted December 10, 2013 Share Posted December 10, 2013 Clogged in injectors maybe. Is it just on start up and goes away after driving? Or just when it is idling? Link to comment Share on other sites More sharing options...
88whitemanche Posted December 10, 2013 Author Share Posted December 10, 2013 Well when at start up it idles fine but the first 5 min it idles a little high to get up to temperature... Then after driving a bit getting to a stop it will idle super low (100-300 rpms) then at the next stop it will idle normal... And just to try something I would turn it off and turn it back on it will idle normal till the next stop...this is also giving a rich smell as well Link to comment Share on other sites More sharing options...
TheDirtyJeep401 Posted December 10, 2013 Share Posted December 10, 2013 I either want to say the fuel injectors or the MAP snesor. That would be my best guess. Link to comment Share on other sites More sharing options...
Oyaji Posted December 10, 2013 Share Posted December 10, 2013 Throttle plate not seating consistently? Dirty throttle body? Dirty/sticking idle air control valve? These are easy to check and remedy - I'd start there. By the way, that engine won't idle that slowly ("100-300 rpms") - the tachometer must be off, too. Link to comment Share on other sites More sharing options...
88whitemanche Posted December 10, 2013 Author Share Posted December 10, 2013 Well the 2.5 has only one injector in the throttle body.... And the how do I test the map sensor? The vacuum line from the throttle body to the map was changed on sat.... Link to comment Share on other sites More sharing options...
TheDirtyJeep401 Posted December 10, 2013 Share Posted December 10, 2013 I was always told to just tap it and sometimes it would work. I can't remeber what else to do to test it. Oh yeah forget about the injector :doh: Link to comment Share on other sites More sharing options...
88whitemanche Posted December 10, 2013 Author Share Posted December 10, 2013 The tachometer is from an 87 2.5... I will be checking those sections today while I try to diagnose the truck Link to comment Share on other sites More sharing options...
88whitemanche Posted December 10, 2013 Author Share Posted December 10, 2013 Il try that when I get out of work... Link to comment Share on other sites More sharing options...
88whitemanche Posted December 10, 2013 Author Share Posted December 10, 2013 This is my rpms at start up Image Not Found This my rpms at a stop Image Not Found I am at a loss is there anyone whose experiencing this? Link to comment Share on other sites More sharing options...
Oyaji Posted December 10, 2013 Share Posted December 10, 2013 Can you check your tachometer against a known good one, like a tune-up tach? Such are more accurate than your dash instrument in any case, and since your dash tach is 20+ years old, it may not be as accurate as it once was... Link to comment Share on other sites More sharing options...
gogmorgo Posted December 11, 2013 Share Posted December 11, 2013 If you look at the sub-1000rpm range on your tach and compare it to the rest of the tach, you'll see that it basically skips the first 500 rpm. Looks to me like you're looking at 700 and then 600. Link to comment Share on other sites More sharing options...
88whitemanche Posted December 11, 2013 Author Share Posted December 11, 2013 I thought the first three lines would be 1- 250rpms 2-500 rpms 3-1000rpms Link to comment Share on other sites More sharing options...
gogmorgo Posted December 11, 2013 Share Posted December 11, 2013 I suppose I could always be wrong, but I always assumed since the spacing of the first line wasn't consistent with any of the other scale marks, they just started at 500 rpm. The spacing is the same going up from 500. The "500" line as I call it (you assumed 250) is also slightly thicker than the x250/x750 lines further up the scale, matching the rest of the x500 lines. One valid reason they could be skipping the first 500 rpm is that gauges are typically inaccurate at the extremities of their range. As a result, most dash gauges typically measure beyond the scale. Also, the engine likely will never be going that slowly, and probably it would stall before it dropped much below 500. It is, I grant you, a little weird that they do it this way. Of course, this is just the assumption I've made about my tach. I could still be wrong, but I'm reasonably confident this is the way the tach should be read. If someone who actually knows one way or the other how the bottom end of the tach should be read, I'm sure everyone would appreciate if they were to chime in. Link to comment Share on other sites More sharing options...
kq.echo.413 Posted December 11, 2013 Share Posted December 11, 2013 There is a air leak some where in your vacuum ...its not a perfect method but ...start your engine and lightly spray areas of your fuel and vacum system with starter fluid ( not around the air box to much).. If you spray a area and the truck idles up there's your problem Link to comment Share on other sites More sharing options...
91Pioneer Posted December 11, 2013 Share Posted December 11, 2013 If you look at the sub-1000rpm range on your tach and compare it to the rest of the tach, you'll see that it basically skips the first 500 rpm. Looks to me like you're looking at 700 and then 600. That's how I think it operates. I don't know for sure, but dropping the first 500 rpm makes a whole lot of sense. Can you just replace all your vacuum lines? They're probably cracked and garbage anyway if they're original. Link to comment Share on other sites More sharing options...
cruiser54 Posted December 17, 2013 Share Posted December 17, 2013 The vacuum lines at the intake manifold, below the throttle body could be the source of your vacuum leaks. Very common. Spraying for them with throttle body cleaner is a good idea. As suggested by gogmorgo, I would just replace them if you've never done so. You should also make sure your intake manifold bolts are snug while you're in the diagnostic mode. Link to comment Share on other sites More sharing options...
88whitemanche Posted December 18, 2013 Author Share Posted December 18, 2013 Ok so I changed a few vacuum lines that caused some of the high idle caused by the throttle body cleaner spray and it helped with idle but maybe about 50rpms and while I was at it I checked the intake manifold bolts and one in the back was loose I turned it with my hand so i tightened it and idle did great and stayed at 600-700rpms then it dropped back down to about 200-300rpms but I only snugged down the top part. tomorrow when I have light I will do the bottom bolts to make sure they are tight and hopefully idle gets better and will clean the relay terminal to make sure that no dirt or junk is in that area Link to comment Share on other sites More sharing options...
carnuck Posted December 18, 2013 Share Posted December 18, 2013 Make sure the EGR isn't sticky/opening when it shouldn't. The IAC is external on that and more of an idle stop. They need lubing once in awhile. Did you clean the throttle body? Gunge around the plate disrupts the air flow. When you first start it, the computer runs the "ice cold" program (like a choke), then it switches to a "warming up" phase until the engine temp is high enough to switch to the O2 feedback. Look down the throttlebody while it is running and see if fuel is dripping from the injector while it is idling. If so, you need a new o-ring kit although a few times I have pulled them and if it wasn't damaged, re-installed with Silglyde grease to slide it in place so it resealed. Link to comment Share on other sites More sharing options...
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