Another Idle Topic!!! (KA24E)

[Vidra]

I am pretty sure I know what the problem is on this one. I just don't know how to correct it. The engine likes to idle around 1500 rpms.... and it will frequently bounce around 1500-2000k (like it will rev up and go down and rev up and down real quick like its bouncing) when in neutral; in addition u can feel it hit (bounce) when the cars in gear and I'm off the gas in that rpm range. I believe its the throttle position sensor... (if thats what its called). But anyways, I've tried resetting the ECU and nothing seems to work. I'm hoping maybe I can go in there and reset it (the TPS) somehow. Any tips?

[Vidra]

BUMP

[Vidra]

UPDATE!!!--> Today I inspected the MAF sensor and wiped it off (all the components were clean). Swapped the ECU with another one in an attempt to see if the ECU was faulty (can still ran the same). Then I unplugged the TPS and turned in the idle screw as far is would go (2 3/4 turn from where it was) and it would only drop the engine's rpms down to about 1200-1300 (normally idles 1500-1900 rpms). Replugged the TPS (which accordingly raised the idle about 50 rpms as it should). So I'm still f*cking confused... I guess this leaves me with a faulty or dirty (even though the engine is a remanufactured engine with only about 15k on it) IACV. Any input guys???

[Vidra]

I can't seem to find a diagram anywhere of the location of the air regulator.

[Acecool]

I used to have the same problem...

What I did was:

New air filter, new injectors... Problem started.

New plugs, new silicone fuel pressure regulator hoses.. Everything dandy :-)

[Vidra]

BUMP!

[180sx]

UNPLUG UR ENGINE TEMPS CENSOR SEE IF IT MAKES A DIFF.

[rogoman]

several things to check:- sticking throttle cable- sticking throttle valve- TPS harness connector pins may be oxidized

[ricebike]

is the AC button on or the hvac settings to blow in the windshield-defrost mode???

other thing to check is the coolant temp sensor; maybe the ecu isn't getting the signal that the engine's warmed-up & is still running in open-loop mode

no trouble codes at all before the ECU swap?

[Vidra]

tried unplugging temp sensor (didn't fix my problems). No sticking cable.... butterfly is closed at idle so I guess no sticking valve. TPS connections look fine. HVAC is never turned on anyways.... Never checked ECU codes though.... isn't there some plug in point or something for a computer to check that ****? I sprayed a bunch of carb cleaner into the butterfly and into the IACV, also put some fuel injector cleaner in my gas. Anyways.... I'm still not sure about this one. The air regulator seems to work fine. But I'm still convinced its some sensor.... I've been driving like this for almost a year now... but I remember last august clear as yesturday... it was a real hot 3 day spell (like 100 +). One day it was fine, the next day it had changed (used to idle right at 700-750).... Like seriously, how does **** jus majically stop working!?

[Acecool]

Did you check the fpr hoses?

[240sx_racer]

Mine kinda idles around 500-1000 rpm and when my radio is loud, it tends to lower the rpm's a bit and then it picks back up. But when my radio isnt loud at all, it just hovers around 700 and stays there. Any idea on what that is?

[nelson8708]

240sx-racer it is because when you radio is loud your pulling more amps from your alternator. It has to put out a stronger field to produce those amps and puts a bigger load on the engine.

Vidra it sounds like your idle air control might be cloged up. Pull the big hose on your intake pipe. Now get some carb or fuel injection cleaner (the spay type). Put the little red tube on the can and slide it inbetween the hose when you put it back on the intake tube. Now with the car running spray little squirts of the cleaner into that tube. Just little squirts like maybe a second long. Then wait a minute or so and keep doing it. That should help clean out the iac valve. Not sure if you used the right screw or not when you adjusted the idle so just incase the screw is on the back of the intak plenum. Stand on the passenger side and just under the fuel line bracket that bolts to the intake there will be the idle air screw.

[240sx_racer]

So basically get a better alternator or go back to the stock system?

[nelson8708]

a better alternator probably wont fix it. I dont know if you can even get a bigger alternator for a 240sx. It will still put a load on the motor when at idle if your system is drawing a lot of power. If you are running a big system ( 1000+watts) I would suggest a 1+ farad capacitor or a second battery in the trunk wired in parallel. That is what my friend did in his olds. He is into the whole big system thing so he would know.

[240sx_racer]

Dang lol, cause ive got 4 100watts speakers but they are only gettin 50watts of power, and then an 800watts sub in the trunk, i need to take it out so its lighter.