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View Full Version : idle problem, not maf, but if removed, idle is ok... then??


guillermo corro
01-21-2008, 11:33 AM
well, thanks a lot first of all for the guys who take some time and read this, hope you guys can help me, because i'm lost now, i have no idea what could be the problem, i'll try to be short, but i'll try to give as much details as u may need.....

main problem is idle... car started few weeks with a little idle problem, i belived it was an old distributor cap, or rotor or something like that because i didnt replace those in a while, so didnt put much attention, once i replaced those... car had the same idle problem..., december vacations were on the door so i parked the car and used a second car... 10 days ago, i started the car, and idle problem got worst!... ugly, car keeps running just by a little rpms up, but go down till like 300... 700,, and jumping between those... if i remove the MAF connector, the idle gets perfect... but i already tested 3 mafs.. one from a running 97, and problem is exactly the same, i already replaced maf connector, so MAf is not on my list right now, but, my main question is why or what is directly related to the maf?,, because as i wrote before, as soon as i remove the maf idle problem is gone, of course car wont rev more than 2000 i think...

one important thing that i notice is a vaccum sound arround the fuel pressure regulator... or maybe on a lower place or somewhre arround that area.. a big vaccum sound, maybe a vaccum problem?, but i already checked as much as possible the hoses over there.. my hand didnt fit all over the place there, but seems that there is nothing wrong, but where is that vaccum noise comming from?,, and why?, is there any good way to check for vaccum problems?,, is that noise normal? ...

another thing is that if the maf is connected, and i remove the hose that goes from the air intake tube, the valve cover and the tube comming from the IACV system or something like that... the car will die.,....

but if the maf is NOT connected, and i remove that hose, car keeps running... and a high vaccum is felt from that hose...

anyone can help me?,,, i'm lost over here,,,, have no idea what to do now....

does the fact that by removing the MAF connector makes the car run smooth means that everything else is ok?, but i already tested the maf as much as possible and i think is working.... hope one of you guys help me with this...

only thing i have in mind is replace the whole intake side. :/

thanks a lot ................. and sorry for a long post........ i'm still searching the forums... but no luck... thanks again GC.

hoo, very improtant,,, car is 1995 240sx with a KA24DE... and the ecu codes are only knock sensor, and cranck position sensor, but i already had those before problem started... but to be honest...i just realized that the knock sensor is fried.... smelted... so i disconect it... could that be the problem?... i've been having that knock sensor code almost since i got the car lol, but a recent overheating problem, arround 2 months ago could smelt the sensor,,,, but after overheating problem (caused for a bad water pump) car was running normal..... or almost,..... well, thanks again, i'll stop writting now... lol

emersonLP
01-21-2008, 11:57 AM
Good way to check for vacuum leaks is to spray some carb cleaner or something around where the leak is suspected, if the car idles up at that moment, the carb cleaner is getting in and burning, you can hear it.

Maybe Idle air control valve is your culprit? Not totally sure, perhaps someone else can back me up.

guillermo corro
01-21-2008, 12:01 PM
and yup, i think that maybe the iavc is the problem, and maybe is sucking too much air because is not working properly and that's why i hear a vaccum sound... i'm going to advance to get some carb cleaner to clean it... and even i'm going to a friend's house to pick up his upper intake mani.. to replace it... i read is not that easy, but well, i'll try, lol.... i already removed EGR system, so maybe will be easier... any good idea on how to troubleshoot a iavc? FSM uses devices that i dont have... any home made method?... because even if i clean it if something is stuck or so... how can i check that?,, thanks GC.

emersonLP
01-21-2008, 12:18 PM
As far as I know, you can either clean it or replace it.

Read through this:
http://www.zilvia.net/f/showthread.php?t=96967&highlight=IACV+clean

Also there are a number of other threads about people with Idling problems and plenty of ideas to sort through.

tt99ol
01-21-2008, 12:36 PM
sounds like you just have one big air leak somewhere, pull the intake off and check all the couplers and all the vacuum hoses, you might as well replace the vacuum hoses because they are cheap and sometimes you cant see a hole in one, while your at it clean your iacv and throttle body

deesz
01-21-2008, 02:05 PM
i would say you have answered ur own Q sounds like ur iacv.......

http://www.zilvia.net/f/showthread.php?t=96967&highlight=iacv

deesz
01-21-2008, 02:05 PM
As far as I know, you can either clean it or replace it.

Read through this:
http://www.zilvia.net/f/showthread.php?t=96967&highlight=IACV+clean

Also there are a number of other threads about people with Idling problems and plenty of ideas to sort through.

oops u beat me too it

guillermo corro
01-21-2008, 03:24 PM
i cleaned the iavc.. and nothing happened.. once i had the carb cleaner... i spray it to find out the air sucking, and just when i spray it over the fourth intake, the one next to the firewall. about the fuel pressure regulator, the car just regulates the idle. so i'm guessing its a bad intake gasket.... i'll be replacing that one, and once i' there i'll replace the vacum hoses... just in case... hope that solve the problem... thanks a lot guys for the ideas.. and yup, maybe the idea of a big air leak its valid... because there is no ecu code. that's why i think that it's something not related with sensors or devices,, because ecu is working, cuz if i remove a connector there is a ecu code, but if i reset codes, and run the car, there are no codes, so ... it should be air leak..... thanks guys... i'll replace that stuff and see.....

tt99ol
01-21-2008, 04:56 PM
could be injector o-rings too

guillermo corro
03-31-2009, 11:31 PM
hey,, problem solved,, few months ago lol.... just bc ive recived few questions, and i think it would be helpful....


YES problem was Intake Gasket..... you can check that by spraying the intake mani... with some Carbu cleaner... if idle gets better,, then theres a vaccum leak,, or air leak.... look for it... if not,, well gl. XD,,, ty all..