What could be the problem???

[scott5]

I am looking at a 1992 240sx hb and the guy said it starts and runs, but it just cant get over 2500rpms. Anyone have any idea what is wrong?

[TheOne]

MAFS, either bad connection to the MAF or just a bad MAFS, with that bein bad the ecu goes into limp mode which doesn't let the car go up of 2500rpms.

[tiger]

yeeas.. I do agree with theone, I have had that prob so many times in my 240/180 owning life. It's the MAF. I bet it idles mad rough, doesn't it?

[scott5]

How would i fix that? Im very new to these motors.

[AmoebAssassin]

As stated, a faulty MAFS will put your car into limp mode. Take off the MAF sensor and disconnect it from the harness (located just downstream of the air box, made of metal, drivers side front of engine bay). The element inside the MAF (in the air stream) must be clean of debris, oil, and gunk. Some people clean em out with rubbing alcohol and a q-tip and GENTLE pressure, others use a dousing of carb cleaner. Once you've cleaned off the element, check the connector prongs for oxidation, clean these out with rubbing alcohol or wd40. Let dry and reassemble the MAF. Reset your ECU and turn the car on. If this doesn't solve your problem, pick one off a junk car.

[scott5]

ok so this isnt a big problem?

[scott5]

what does MAF exactly mean? sorry for the stupid questions.

[AmoebAssassin]

Yeah, its not that big a deal...electrical problems can be PITAs to pin down but are more or less easy fixes. MAFS stands for Mass Air Flow Sensor or Manifold Air Flow Sensor, depends on who you ask...either is technically correct.

[tiger]

so let us know when you fix it

[scott5]

thanks guys for the help. I am thinkin about buyin this one thanks,

[AmoebAssassin]

No problem, but i really suggest you try cleaning it out before you buy one...MAFS can be pricey and there's no guarantee a junkyard one will work (though they usually do).

**EDIT**I just realized you meant buy the car, not a new MAF...silly me Good luck with the purchase!
Modified by AmoebAssassin at 7:49 AM 7/3/2005

[scott5]

He said he already reaplaced it and it still wont go over 2500 rpms.

[AmoebAssassin]

Did he reset the ecu after it was replaced? Were the connectors clean, and was the MAF a matching type for the ECU (not an s14/z32 MAF)? Grab your multimeter and a KA24DE wiring/pinout guide and check the harness connections at the ecu plug and the MAF plug...You should have minimal resistance between the maf connector prongs and their corresponding ECU connector pins. It's entirely possible that with age, one of the wires has broken in the harness and needs to be replaced. You can do this yourself, but again, HUGE HUGE HUGE pain in the ***.