# Rough idle. Help!



## jerryclement (Nov 21, 2005)

I have read through my Chilton book and i also noticed under the hoor of my 92 s13 that the normal idle for the KA24DE is 700 RPM. Since i have owned the car i have never seen it below 1000. Right now it averages 1200, sometimes dipping down to 600-700 and as high as 1800. Also, when i start the car cold sometimes it has trouble igniting fully and will bog around 500RPM and "try" to kick on. Even giving it gas during this does nothing, like i'm not even pressing the gas. One more thing...I don't know if this is related but the car have very little "pull" through first gear, and little to no pull after 4000 RPM in 1st gear. Anyone have any ideas what would be causing this?


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## BoostedSE (Jun 26, 2005)

fuel filter or possibly a clogged IACV


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## jerryclement (Nov 21, 2005)

What is IACV? Sorry i'm somewhat of a noob when it comes abbreviations. But thank for the tip, i'll check this out this weekend.


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## jerryclement (Nov 21, 2005)

Nevermind, found out it was the Intake Air Control Valve. WIll check it out this weekend during my full tune up.


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## 240sxstud (Sep 20, 2005)

jerryclement said:


> Nevermind, found out it was the Intake Air Control Valve. WIll check it out this weekend during my full tune up.


Check your hoses as well, could be a possible vacuum leak


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## jerryclement (Nov 21, 2005)

Well i just changed the fuel filter and it solved a few problems. When i got the hood open the filter looked like it was the original filter (i doubt it though) but it took some struggle to get off. After i replaced it the car fired up right away without any trouble what-so-ever. I managed to drop the idle by about 200-300 and now it sits steady at about 950, and the rough idle seems to have stopped. I am very happy with the results so far. I also replaced the filter on my intake (HKS, the green mushroom one) so that could have helped too. Once i got the car out on the road i got a noticably smoother acceleration, though first gear still doesn't seem to pull as much as the rest. Is this common among the KA24DE?

This Thursday i will get to the throttle body and clean out the IACV. Is this part attached to the throttle body? Also is the screw that adjusts the idle visible and adjustable when everything is attached to it? I'm still very noob at this car repair thing, but replacing the fuel filter went well and was a nice thing to get my feet wet. I'm hoping that will fix the idle and get it back down to 700.

On a side note. If my air conditioning doesn't work and the compressor isn't running would this cause the idle to be higher? I was talking to my dad about this and he brought it up. Just wanted to check and see if that was a possibility.

BTW Boosted, i tried to add to your reputation, but all it says is you are offline. Thanks for the advice. I'm hoping i can get this car running as well as i can before i start pursuing after market parts. I appreciate the help.


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## jerryclement (Nov 21, 2005)

Well i spoke too soon. On my lunch break i drove to get food and it appears my idle has jumped back up to 1200, but the roughness and acceleration decreases are still gone. So tomorrow i will check out the trottle body and IACV. Also that dam rattling from the timing chain guide is iritating the hell out of me, i get wait to get that open.


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## rogoman (Dec 16, 2004)

jerryclement said:


> Well i spoke too soon. On my lunch break i drove to get food and it appears my idle has jumped back up to 1200, but the roughness and acceleration decreases are still gone.


You could very well have a major vacuum leak. To check the intake system for a vacuum leak, attach a vacuum gauge to a full vacuum source. A good place to connect to is the charcoal canister. There should be three hoses connecting the carbon canister. Two of the hoses go to a purge valve that's built into the canister. The second larger hose off the purge valve should be your vacuum line. With the motor fully warmed up, the reading at idle should be 18 - 20 InHg. At 3,000 RPM, it should be around 21 InHg.

If readings are under 18 InHg, check the intake manifold nuts to make sure they are tight. Also check the intake plenum bellows at the throttle valve and at the MAF for cracks or loose clamps; check other hoses that connect to the plenum.


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## jerryclement (Nov 21, 2005)

That may be a bit out of my league right now, but i'm trying to learn and tend to be very adept at new things. Is there any way you could post some pictures or links to pictures that i could see? I'll take a look tomorrow (Thursday) when i remove my top timing guide and check the IACV for clogging. I do want to learn this because i am choosing to keep my 240 and work on that as oppose to a new car and i want to get everything working right before i pursue after market parts. I appreciate the advice.


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## 240sxstud (Sep 20, 2005)

jerryclement said:


> That may be a bit out of my league right now, but i'm trying to learn and tend to be very adept at new things. Is there any way you could post some pictures or links to pictures that i could see? I'll take a look tomorrow (Thursday) when i remove my top timing guide and check the IACV for clogging. I do want to learn this because i am choosing to keep my 240 and work on that as oppose to a new car and i want to get everything working right before i pursue after market parts. I appreciate the advice.


An easy thing to do as well is just take it in for a diagnostic, they're usually reasonable in price, and it saves a lot of headaches


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## rogoman (Dec 16, 2004)

jerryclement said:


> Is there any way you could post some pictures or links to pictures that i could see? I'll take a look tomorrow (Thursday) when i remove my top timing guide and check the IACV for clogging.


It's the second hose down on the left side in the picture.


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