Hello everyone!
1993 Nissan 240sx - 175,xxx miles
KA24DE - Manual
When coming to a stop, I start braking until around 1,000rpm/1,500rpm, then press in the clutch, and the RPMS go almost to 0, sometimes stalls. When it does not stall, it catches itself and jumps from almost 0 back to 750rpms.
Does not matter if A/C is on, full electrical load, etc…. Pretty consistently does it each time regardless of external factors.
I have checked for vacuum leaks (none), cleaned the Idle Air Control Valve (IACV), Throttle Position Sensor tested fine, Mass Airflow Sensor (MAF) and coolant temperature sensor seems to be working.
A lot of 240sx KA24DE guys say to just raise the idle. I can, but would prefer to find if there is any insight here before I do so. This vehicle does have a lightweight flywheel, but this has been happening recently, and the flywheel has been on for years with no problem.
Any help is highly appreciated, I want to pull my beard hair out at this point.
Hello everyone!!
Great news:
After looking at all vacuum lines, checking sensors, cleaning intake/throttle body/IACV/etc…. I found that at some point someone (hopefully an honest mistake) fully screwed in the idle air control screw adjustment.
Ancient forums from years ago made mention that if you unplug the throttle position sensor (TPS) with engine off, turn the engine on, and the engine dies immediately, that the screw is all the way in. That exactly happened to my 240. I began turning the idle adjustment screw on the IACV counter clockwise little by little and starting the engine until it finally idled on its own. Plugged back in TPS, purrs perfectly.
It’s a huge relief to have this resolved. The 240 is idling perfect now.
Thank you to everyone who responded. Hopefully this will help someone in the future. 😎
I’ve honestly been throwing parts at it chasing it down.
That's not a good way to approach a problem, it rarely produces a good result. Are there any OBD1 codes? You can find a repair manual at the link below which may help:
https://charm.li/Nissan-Datsun/1993/240SX%20L4-2.4L%20%28KA24DE%29/
When checking for vacuum leaks be sure the check the intake manifold as well as vacuum hoses if you have not already done so.
Totally, I agree!! I’ve been diagnosing this for some time now that when I started going through things, some things were old, so I just started replacing due to age, not necessarily because it was not working hoping it would work dang it.
No OBDI codes as of yet, looked at the ECU and no red light blinking a code.
I have checked all the intake hoses, vacuum lines, and everything I can see except the EGR and swirl valve on the back of the engine. I took some pictures on my front facing camera on my phone to get back there (although slightly blurry), and didn’t notice any cracks or broken lines, but that does not mean there aren’t any.
The 240 idles great, great power, no lag, just this one strange issue.
Some older cars use a dashpot to prevent the throttle from closing too quickly. I don't know if that car uses one. I could also see the EGR valve possibly causing the symptom you're experiencing. It also looks like there's a gadget controlling the EGR valve that is triggered by exhaust back pressure., as well as some other gadgetry. Possibly something to look at.
https://charm.li/Nissan-Datsun/1993/240SX%20L4-2.4L%20%28KA24DE%29/Repair%20and%20Diagnosis/
(EGR section is under Powertrain Management/Emission Control Systems/Exhaust Gas Recirculaton.)
Well when they're that old all kinds of things can go wrong. Ignition system fuel system. You name it. But often if you do my video make your car run better with a little spray cleaner that can help. If not, get my friend Bernie from Albuquerque's fuel cleaner and put it in the gas tank and drive it a couple hundred miles. Just Google. Bernie Albuquerque ATS cleaner
@scottykilmer thank you Scotty!!
Been watching you since 2007, I really appreciate the feedback.
I will for sure give the fuel cleaner a go. It does have new injectors, fuel filter, plugs/wires/distributor cap/rotor, I’ve honestly been throwing parts at it chasing it down.
Will come back and let you guys know how it goes!