weird Idle problem

[sykikchimp]

Well my car is acting kinda funny. Has been for a while.

When I'm driving her and I get ready to come to a stop, I push in the clutch and hit the brakes. The Idles drops VERY low. About 350-400rpms. It does this every time I let the car idle. The weird part is that it only does it when the car is moving. as soon as the car comes to a complete stop the idle goes back up to 750-800rpms. weird huh? If I have the A/C on it will get a little lower and actually die. (which makes sense since it would add extra strain to the engine.) I have replaced the intake with an Injen CAI, and it is acting the exact same way.

I tried cleaning the IAA valve and throttle body a while back, and it didn't seem to help. Of course I couldn't figure out how to get to the IAA valve so I just pulled the hose off the intake and sprayed throttle body cleaner in there. (bout a half a can) I don't think the O2 sensor is the problem cause I'm getting pretty good gas mileage. (22 mpg w/ spirited driving)

What do you guys think the problem is? I have a few ideas but I thought I'd bounce this off you guys for some help?

[ant]

My '91 is doing almost the exact same thing the only difference in what you described is that whether the car is rolling or not doesn't appear to affect it.  Mine idles rough, and will do what you talked about after coming to a stop.  I have chalked my prob up to a vacuum leak that I can hear but can't find, it is behind the engine but the sound comes from the opposite side of the back of the engine from both sides.

[transient]

when's the last time you had a tune-up?

[sykikchimp]

well, when I got the car about 3 months ago I did a basic tune up myself, but didn't mess with anything like timing etc.  Just changed the Plugs/wires, sprayed throttle body cleaner in the TB/IAA.  Wiped out the MAF.  Put full synthetic in it.  replaced the valve cover gasket.  Thats everything I've done.

[sykikchimp]

ne ideas?

[Alias]

Same crap here. Hope to fix it soon, the A/C is nice in the summer.........

[Ser_rah]

EGR malfunctioning?  Did you change the rotor, or distributor?  Sometimes that needs to be done if you have high mileage.  I don't know how much that costs though.
 
 You should be albe to get some cheap hp doing the timing, if you don't overdo it.  I broke my light the other day so I can't do it yet.  (stupid stupid)

[allshow]

I had a similar problem....my car's idle would drop and rise on every stop that im on, lots of people suggested it was the mav, aiv, or whatever, but when i took my car to get fixed it was a broken intake manifold gasket that was leaking...apparently he told me someone tried getting into my intake manifold because the screws were all stripped, this is why i don't trust mechanics from the pennysavers

[9524tee]

time for a rebuild, i wasted hundreds of dollars on my s13 trying to get it to run right, finally i just got a rebuild and it fixed it

[BlackFox]

Eeesh... engine rebuild, time for turbo &nbsp;<img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/sneaky.gif" border="0" valign="absmiddle" alt=':pissed:'>
That's the one thing I like about my '76 Mercedes, adjustable choke from the drivers seat. I'm not sure exactally how the throttle body is on the 240, because I'm not getting mine for another 2 weeks (damm, have to sell my celica, my 240 is ready and waiting) But my Mercedes throttle body cable loosens up sometimes, you might have to readjust it, that should bring your idle back up.

[tnord]

try driving real hard for like 30 min, then see if it still happens. i have idle issues as well, the check engine light has came on twice and read fried EGR valve. driving it hard blows the carbon or whatever the hell is in there making it stick out so it functions normally for a week or so then it's back to same ol same ol. i'm just waiting to get back home to get it fixed by the tech's at work whom i know and trust.

[sykikchimp]

yeah tried the driving it hard thing. &nbsp;I have noticed that it is not 100% persistant. &nbsp;Seems to do it more when the engine has been run for a while. &nbsp;Maybe because the FICV is off? &nbsp;It has to have something to do with the idle control/vacuum system. &nbsp;I'm gonna spend this comming weekend chasing gremlins.. &nbsp;Might take the whole damn intake manifold off.

I'll keep you guys posted on the outcome.

[rps13sh]

looks like alotta people have this problem and no one has really gotten to the bottom of it. if i can find my idle valve i think cleaning would help. anyone have a pic or can tell me where it is in detail?

[kandyflip445]

Why Do Ppl Bring Back Oooooooooold Threads!?!?!?!?!?!!?!?!?!?

[rps13sh]

because if you start a new one and ask the same fawking thing. people bitch and tell you to run a search on old threads!

[alex240sx91]

i had the same prob and ppl keep on sayin stuff like plugs and fiters and yadda yaada anyway i finaly fixed it on my car...it was the fast idle control valve FICD ...i took it out and tested it and it work fine......? problem was still there tho.. but when i put a seperate groun wire on it vola it came to life.... hope this helps

[rps13sh]

yes yes! now can you tell me where the idle valve is?

[mistaanime]

well..i have the same problem.my car would use to stall...when i juss throw it in netual and clutch...but not anymore..i adjusted the Throttle line a little bit..so idles bout 1100 now..but drops to 800...people said..i can use a tune up..or..it could be the MAF malfunctioning..thats case..juss buy another one from people in the forum.

[alex240sx91]

the ficd is very small and it is near the fire wall on the back of the intake and it has (on my car) one blue plug comin out of it and it screws into where the idle speed adjustment is. when you take it out just put power to the 2 termainals +and - try both ways and see if it works ...if the little plunger move or cliks it is fine and you should try grounding it ! so if it works tell me and i will tell you which wire on the blue plug to ground out

[rps13sh]

ok will look this weekend. thanks

[MrSpArkle]

well..i have the same problem.my car would use to stall...when i juss throw it in netual and clutch...but not anymore..i adjusted the Throttle line a little bit..so idles bout 1100 now..but drops to 800...people said..i can use a tune up..or..it could be the MAF malfunctioning..thats case..juss buy another one from people in the forum.

yeah, i got the same problem i think. everytime i let the car go into neutral the rpms drop below my idle (~1100, a lazy mechanic must've done that...) to about 800. which means if my idle were at a proper 800, the car would stall. i'm gonna mess with that magical ficd valve next weekend and see what's up.

[MrSpArkle]

yeah, i got the same problem i think. everytime i let the car go into neutral the rpms drop below my idle (~1100, a lazy mechanic must've done that...) to about 800. which means if my idle were at a proper 800, the car would stall. i'm gonna mess with that magical ficd valve next weekend and see what's up.

some quick research yielded this gem:
http://www.240sx.org/faq/articles/idleirreg.htm

"Most 240sx's eventually have a problem idling. This is related to the IAA valve which control the air mixture during idle. The two options to fix this are to have a dealer adjust the valve or simply have it replaced.

The symptoms are clear: as you hit the clutch or lay off the gas and the car begins to slow and idle the RPMs may drop (sometimes quite rapidly) to extremely low levels, sometimes actually stalling completely. If this is happening have someone check out your IAA valve and you may wish to clean all the ground wire connections for the car's ignition and injection system.

I hope this helps.


Chris L.
'90 240sx 143k"

[twitchy]

Well I hate to ressurrect but i need to ask some questions and this thread looks appropriate.
First Off: 1993 with header and intake
new plugs, fuel filter, recently cleaned intake tract, EGR is disabled, as is the PAIR valve and other stuff. (disabling these things had teh engine running fine for months before all this started to happen)

I have the same problem where the revs drop (to about 400 rpm) as i slow down in neutral but only while in motion.....all other things being equal when the car stops moving they go back up *DID ANYONE FIGURE THIS WEIRD THING OUT??* This only happens sometimes, other times its fine.

Now the real kicker, and this is weird, is that in my case i have a problem getting the car to start up when its been sitting FOR A CERTAIN, PRECISE WINDOW OF TIME. If i shut it off for 5 or 10 mins, it starts fine. If i leave it overnight it starts fine. Anywhere between about 30 and 90 mins will see it start to sputter as soon as it cranks over, and it dies very shortly after. It NEVER starts when i leave the gym, which is always almost exactly 1 hour 15 mins. This occurrence doesnt vary with outside temperature. Even flooring the gas, nothing happens at all when it is going to stall. The only way to get it going again is to repeatedly start the car and pump the gas, and it takes on average 4 tries but always eventually starts. Once started there is some intermittent hesitation in acceleration mainly in lower revs, and the car generallly feels gutless...but sometimes it hauls properly...usually not. In fact i raced the 8th mile this weekend and only got 12.04 seconds. Yikes.

When this all started i was screwing around with a voltmeter and determined the MAF and coolant temp sensor to be within spec as per the FSM. Then i noticed a vacum leak at the back of the engine, in the line that connects to the swirl valve and the fuel pressure regulator. Upon replacing that line, the car ran better than it ever had for about 2 weeks. Now i have the same exact problems but that line is fine. So that doesnt seem to make sense to me at ALL.

Does anyone have any idea why mine is sensative to how long it has been off for like this?
or any idea what i could be missing.. There were no CEL codes by the way. Any help is greatly appreciated. I dont want to pull out any more hair and i dont want to take the car in.

Thanks a bunch

Twitchy