1991 S13 240SX KA24DE Running Rich

[erichard]

Hello all. Forgive me for sounding like a n00b, but I'm trying to develop my automotive skillz, and it's an ongoing process.

Anyway, I'm having a problem with my KA24DE. Actually, I'm having several, like a rattling clutch and the infamous timing chain rattle, but the one that's causing me to join the forum is a problem with the engine running real rich sometimes. This usually manifests itself as a rough, sputtering idle, along with a gasoline stench out of the exhaust, or maybe a stumble at part-throttle. Also, my gas mileage has sucked for the past few months.

I started by replacing the exhaust o2 sensor, which was (of course) covered in black soot, and the spark plugs, which were likewise coated. That set me back a few dollars, because this was back before I knew where the o2 sensor was located. As it turns out, the o2 sensor is the single easiest part to replace on the entire car, except for maybe the gas cap, and I have since taken it out and cleaned it a couple of times. Live and learn .

That kept the ol' girl running fine for about 24 hours or so, and then she resumed running like a pig. Okay, so I took out the MAF sensor, since that seems like something that everyone around here recommends. It looked pretty good, but I took some carburetor cleaner and sprayed it on the little sensor element anyway. I also cleaned off the newly gunked-up o2 sensor and spark plugs.

As soon as dry weather rolled around again, she was back to coughing and sputtering and bucking at inopportune times. So, I decided, "hey -- maybe the fuel injectors are leaking?" So, I got some new Deatcshwerks (sp?) fuel injectors -- yes, four of them -- and replaced the old ones. I don't know who here has tried replacing the injectors in their S13, but if there's a way to do it without destroying the old ones, I would love to hear it. As it was, my Craftsman locking pliers proved their worth yet again, and I learned a valuable lesson which unfortunately I cannot recall at this moment.

As you may have guessed, a few days after that traumatic episode, the ol' girl was back to coughing and pitching and bucking and just generally being a royal *****. So, here I am with a few questions:

1) I would like to replace the idle air control valve (IAC valve), but I don't know where it is. The closest I could find on the forums was that it's "near the firewall," but obviously that's not much help. Also, do I need to replace this part? Is there some way to test the one that's in there?

2) The PCV valve also seems like a good candidate, but it sounds like I can't get to it without either a) draining the radiator, or b) removing the alternator. I guess I don't need help with that one, I just wanted to complain .

3) How do I read the ECU codes in a '91 240SX? As near as I can tell, you have to unbolt the ECU from the body. This is unfortunate, because it looks like the ECU was the first part of the car built, and then the rest of the car was assembled around it. Seriously! I have no idea how to read the codes from it, because (apparently) the only way to access it is by drilling a hole in the firewall. I'm assuming, by the way, that the ECU on this car is the little electronic-looking box behind the kickpanel in the passenger side footwell.

4) Could this be an ignition problem? I've checked the resistance of the primary and secondary coils in the ignition coil per the Chilton's manual, and they seemed swell. So, too, did the resistances of the wires leading to and from the coil.

Thanks for reading this far. Any help you could offer would be greatly appreciated!

[vancouverbc]

look for iacv in tutorial link in my signature or idle which shows pic of idle adjusting screw on iacv

[vancouverbc]

check your coolant temperature sensor. look up temperature, fuel injector, and codes in my tutorial link in signature to answer a few of your questions.the coolant temperature sensor can cause a rich condition.