# the neverending idle problems



## 240fanboy (Feb 8, 2005)

ok...
this engine is seriously making me want to cry.
i have a 1990 240. ka24e. when i bought it... i noticed it would have a rough idle every once in a while(around 500rpm). so when i got it home i replaced the fuel filter. it didn't fix the problem.

i took it to a mechanic.
compression is good.

i took it to nissan because i wanted them to check the codes.
they told me my injectors and connectors were bad. and they could fix it for the very low cost of $1100. i told them to screw themselves and did the job myself. i also replaced the fuel pump.

so far ive replaced the following:
- fuel filter
- injectors
- fuel pump
- oxygen sensor
- maf sensor
- distributor
- plugs
- plug wires

i still have the rough idle(fluctuating between 400-650 rpm).
every once in a while it'll idle fine. whether it's to the next stop light or a few hours. and some mornings it starts up fine, purrs nice and smooth... and other mornings it starts up like a bastard and runs REALLY rough until it warms up(and then the rough idle is still there).

anyone have any ideas?
please?

*goes off into the corner and cries*


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## K-1 (Jun 15, 2004)

it's probably the AIV and IAC systems, there are probably 50+ posts in every 240sx forum about fluctuating idle because of these...searching is a good thing. They are vacuum + solenoid regulated idle control systems. If you do a search for these systems, you'll find all the info in the world.

You can either clean and fix these systems (for emissions in Cali), or totally disable them.


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## Chris90FB240sx (Feb 25, 2005)

you would also need to check for vacum leaks, and you can turn the idle up on the ECU so maybe you can have it idle at 800 so it wont drop to low to stall.


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## JDM240Turbo (Jan 21, 2005)

240fanboy said:


> ok...
> this engine is seriously making me want to cry.
> i have a 1990 240. ka24e. when i bought it... i noticed it would have a rough idle every once in a while(around 500rpm). so when i got it home i replaced the fuel filter. it didn't fix the problem.
> 
> ...



Buy an sr20det.


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## sunnydet90 (Sep 10, 2004)

240fanboy said:


> ok...
> this engine is seriously making me want to cry.
> i have a 1990 240. ka24e. when i bought it... i noticed it would have a rough idle every once in a while(around 500rpm). so when i got it home i replaced the fuel filter. it didn't fix the problem.
> 
> ...


 tried cleaning the throttle body? mine would do that too some times i would pull up to a light and it would die then sometimes it would do nothing

Don


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## earkicker (May 6, 2005)

i have the same problem as you once and a while. i work at an auto shop and i ask my boss what the problem was and he instantly replied it was the altanater. what happens to my car is that when my car is at idle it flucuates a little but when i use the power windows or turn on the radio the rpms drop to about 500.


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## K-1 (Jun 15, 2004)

Chris90FB240sx said:


> you can turn the idle up on the ECU so maybe you can have it idle at 800 so it wont drop to low to stall.


The idle control is actually a screw on the IAC (or AIV, i dont remember) assembly, it is not controlled through the ECU.

Clean your throttle body plate, check all vacuum lines, check the grounds on your engine / feul injectors / IAC / AIV.

If you still have problems, then your going to want to disable or clean out the IAC.

If you need to find more info, go to 240sx.org's FAQ



JDM240Turbo said:


> Buy an sr20det.


Most pointless reply I've heard in a while.

This is a problem that can be fixed FOR FREE with a little research and manual labor.

[sarcasm]But spending $2000 - $2500 is the smarter way to fix this problem.[/sarcasm]




earkicker said:


> i have the same problem as you once and a while. i work at an auto shop and i ask my boss what the problem was and he instantly replied it was the altanater. what happens to my car is that when my car is at idle it flucuates a little but when i use the power windows or turn on the radio the rpms drop to about 500.


That is normal. If it bothers you though, you can check + clean all grounding points on the car, and even spend $$ on those fancy grounding kits.


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## Chris90FB240sx (Feb 25, 2005)

> The idle control is actually a screw on the IAC (or AIV, i dont remember) assembly, it is not controlled through the ECU.


Then why is there a nob on the back of the ECU that says Idle adjustment?


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## K-1 (Jun 15, 2004)

hmmm... There may be more than one way to adjust the way the car idles... I could be wrong though


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## little240boy (Jan 13, 2004)

check your FSM, there is only one screw to adjust idle. If you look on the ECCS near the back there is a philips screw that increases/decreases idle rpm. Wanna know something really bizzare. I was having the same problem but then I got my timing chain/guides replaced and the timing was a few degrees off before the fix. Now the timing is fixed, doesn't rattle and my idle RPM has been really consistent, I mean I've never had a problem with it since. This is an expensive fix however but that rattle can drive a 240 owner mad anyways!! Or just KA24DE(T) it or if your like me, getting an RB20 next month


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## sunnydet90 (Sep 10, 2004)

little240boy said:


> check your FSM, there is only one screw to adjust idle. If you look on the ECCS near the back there is a philips screw that increases/decreases idle rpm. Wanna know something really bizzare. I was having the same problem but then I got my timing chain/guides replaced and the timing was a few degrees off before the fix. Now the timing is fixed, doesn't rattle and my idle RPM has been really consistent, I mean I've never had a problem with it since. This is an expensive fix however but that rattle can drive a 240 owner mad anyways!! Or just KA24DE(T) it or if your like me, getting an RB20 next month


 oooooo rb eh? 3 months til mine hehe

Don


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## little240boy (Jan 13, 2004)

3500 for an entire r33 clip! how the! I just picked up some killer r33 GTR seats, can't wait for them babies! I picked em up at RBmotoring, expensive but cheaper then brand new aftermarket seats that arn't usually as good anyways! Keep updates on your progress Don, I'm excited to hear how things are going! I'll do that same.


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## sunnydet90 (Sep 10, 2004)

little240boy said:


> 3500 for an entire r33 clip! how the! I just picked up some killer r33 GTR seats, can't wait for them babies! I picked em up at RBmotoring, expensive but cheaper then brand new aftermarket seats that arn't usually as good anyways! Keep updates on your progress Don, I'm excited to hear how things are going! I'll do that same.


 no prob man i may do a few write-ups on how-to stuff when i get the clip in. the first thing that i'm doing when i get it is the rhd conversion that way i can get everything the way i want it.

Don


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## J250sx (Feb 14, 2009)

have u check ur idle control sensor yet if u need anything ill see what i can pull up on the idle problem for u


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## Trippen (Feb 21, 2006)

JDM240Turbo said:


> Buy an sr20det.


LMAO JDM240Turbo......Japan domestic(meaning in JAPAN not ship outside their country) market didnt have 240's ..Since the 240 number was off the motors cc minus the last zero..IE 1800cc also know as CA18DET the true 180 or the 2000cc know as the sr20det...and the KA24de or e if its single cam ..oh and since you didnt know that CC=Cubic centimeter....Oh and the t at the end of the motor designation means turbo......Like My KA24DE-T.


Any way...with that said...Orings/seals on your injectors can cause this. If it does it after running for a while I would look to see if you see gas around your injectors. Vac lines for an 89 just start replacing them will correct a whole bunch of issues...The IAC usally starts the funny idle with in the first 5 min. If it goes away sometimes check vacuum and injector orings.


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## rogoman (Dec 16, 2004)

If all else fails to fix your problem, check into a sticking problem with the EGR valve.


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## matt_101 (Feb 5, 2007)

Remove all your emissions and check for vacume leaks. if that doesn't fix it - then i'm putting my money on the IACV.

If you changed all that stuff, make sure you reset the ecu - makes a difference. let it idle for a few mins, race the rpms to 2k and let it come back down. then take it for a dirve.(stop and go traffic) come home and let it idle some more. Thats not based on any manual, but it works for me.

I dunno about all ka24e's but mine idles alot better after a ecu reset when something is replaced. 

sorry if someone already said that, i didn't read the other posts....


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