Idling problems, what does it mean when the rpm goes up and down?

[ka24deNewB]

I have a 1993 nissan 240sx hatch. the car itself has 210,xxx miles on it and just recently got it like 2 weeks ago. The thing i've done to it so far are, Tune-up (oil change, oil filter change, air filter, spark plug, plugs cap and rotor. I also did a flush and bought some fuel injector cleaner. The car still runs the same way i bought it. The idle is still ruff. My cousin said it is running retarded like it's gasping for air or fuel. Any ideas? Vac leak? MAF?

[littlred]

Hey I have the same problem with mine same engin.......I have tried when it stalls turning off. letting the computor reset and crank again some times it works some times not......did you get a anwser.......

[navysnail]

there is a good ammount of things that can cause this: make sure your sensors (maf, coolant, tps, idle) are putting out the correct output.

[The Mic]

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.

[navysnail]

when it happened to mine, it would drop and if you hit the clutch then turned, the load from the ps pump would kill it. i went around the engine with a multimeter, and turned around, my elbow hit the MAF connector and it jumped up to the 800rpm idle and stabilized , just somthing to check, its easy to test and it gets that eliminated off the bat

[ka24deNewB]

MAF, sensor seem to be fine, i disconnected it and the RPM just went up, Then down, Then up, Then down. SO i plug it back in again. and then the Rpm Went down to 800, Idling, but then it goes up and down again. Back to it's origional problem. I'm gonna try to clean all the ground wire and clean the IAA valve, can anyone tell me how to located it? and how to clean it?

Also, i notice when i'm driving, i try to keep the car at 2000 rpms in 2nd gear or 3rd, the car jerks a bit. is that normal?

[navysnail]

in normal driving you should have your car at or above 2k on our cars, and no, it shouldnt jerk when going at a constant speed. have you done a basic tune-up lately?

[littlred]

Hey S13Guy.......got the TAA value and of course the LilRed is running fine at this time......but hope once it is changed I never have the problem again.....thanks

[The Mic]

um.. sure?

[Big Manne]

fuel pressure regulator maybe. i have a friend who had a 93 240sx and his fpr was bad . it would sputter and stuff under throttle. he replaced it and it ran fine. try fuel pump too or maybe the fuel sock on the pump is clogged up