I've tried everything, the rough idle is still here. Please help!!
#1
Well, I haven't tried EVERYTHING... At least not yet. Alright, first the symptoms: upon startup (most startups hot OR cold) jeep will start and idle to 1000. Then after 10-60 seconds will drop to 700, which is ok. But it will then drop into the 200-400 range and will actually rev itself back up to prevent it from stalling. If I don't let it idle (say I take it on a drive after starting), it will seem as though the power is restricted and sounds like it wants to die out until I give it more gas. Once I do it will make a popping noise and the rpms will shoot up and I will have to brake. It will do this a few times and I have to go above 30mph to get rid of it. But once its gone, its home till I start the engine again, it won't do it at stop signs or anything. Ok, now what I have done to try and get rid of it: new cap, rotor, wires, plugs (champion copper), new high flow cat, cleaned iac, replaced tps, seafoamed vac lines, gas tank, oil, took tb off and cleaned it. I do regular oil changes and I have no overheating issues. I guess the only things left to check is: map sensor, cps, and.....? It is throwing a code for the nss and one that does not show up on their computer. Please help what could be wrong with my green bean?!
Last edited by greenxj21; 08-20-2012 at 11:26 PM.
#4
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The NSS code can probably be cleared by cleaning the NSS and conector. I'm curious what the other code might be. Their scanner won't identify the Pxxx code?
I'm also suspicious that your IAC is sticking or not responding correctly despite being cleaned. Once you hit 30 mph it's fine until you shut down again? The problem comes back even if you re-start immediately?
I'm also suspicious that your IAC is sticking or not responding correctly despite being cleaned. Once you hit 30 mph it's fine until you shut down again? The problem comes back even if you re-start immediately?
#5
Originally Posted by Radi
The NSS code can probably be cleared by cleaning the NSS and conector. I'm curious what the other code might be. Their scanner won't identify the Pxxx code?
I'm also suspicious that your IAC is sticking or not responding correctly despite being cleaned. Once you hit 30 mph it's fine until you shut down again? The problem comes back even if you re-start immediately?
I'm also suspicious that your IAC is sticking or not responding correctly despite being cleaned. Once you hit 30 mph it's fine until you shut down again? The problem comes back even if you re-start immediately?
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#12
CF Veteran
A thing that you havent addressed yet is the CPS.
Your 99 will have it fail at some point during its life, as with all 4.0 's and the stalling/popping sound, then picking up again could very well be this.
Replace this next. The NSS has nothing to do with this and the rough idle can be other things as welll, but you addressed a lot of them already, try the CPS replacing first. Get a quality one, because cheap once are notorious for being faulty, leaving you thinking you addressed the CPS already, but not solving the problem.
Let us know how you go.
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