Intake Sensor, help me out

[S3t0_S13]

Hey guys, i just bought a 1992 240sx hatchback, it has a new clutch, brake rotors, full Apexi Exhaust, undercarriage sway bars, suspension has been lowered, and some Giovannis 17' all for $3400. The car has 140,000 miles but runs strong (good deal ?)

.....but not strong enough, the owner told me something about the intake sensor that goes into the stock air filter box has some sort of sensor in it that makes it clog, and ruins the gas/Oxygen mixture. Does anyone know where that is and how i can fix it?? thanks alot

[Skidmark]

That would be a Mass Airflow Sensor (MAS). Yes they do go bad, yes they will mess with your Air/Fuel ratio's when they do. What kind of symptoms are you having??

[slpr240]

just go to a junkyard and buy a new maf and j replace it. on your car it will be between the actual plastic intake and the plastic airbox in your driver side fenderwell

[Ni2s4s0aSnX]

That would be the Intake Temperature Sensor and its on the side of the stock air box. I don't know why these guys are talking about the MAF.

[S3t0_S13]

well, the car barely passed smog, 2 much gas, and u can also smell it to, and the previous owner said its behind the intake box, a hose with some sort of metal that electricity runs through, he says having that fixed give a 10-15 hp back that im losing right now

[Ni2s4s0aSnX]

i doubt that you would be losing 10-15 horsepower from that, I seriously doubt that you're losing any, but it would cause you to not pass emmissions because its a part of the EGR system.

[InsanityInc]

Well, lets get one thing straight up front: The previous owner was an idiot ricer. Got that? Good. Let's move on:

As far as I know, KAs do not have an Intake Air Temperature Sensor. I can say for sure that s13s do not, and I'm pretty sure s14s don't (but I could be wrong about s14s). Instead of an IATS, the KA uses a temperature compensation resistor inside of the MAF itself. Your MAF may be bad, but it doesn't get "clogged".

Basically, if you REALLY want to figure out what's wrong, find a mulimeter and learn how to use one. Otherwise the least you could do is give us a better description of the problem you're having. It seems like you're running rich, but for all we know that could be caused by an injector leak and not any management problem whatsoever.

My first suggestion would be to pull the spark plugs and look at them. If one is black and wet with fuel and the others are fine then you have a leaking injector.

[All_Motor_KA]

Yo dude, 240's DO have an air intake temp sensor. It is located inside the air box itself. When you put a cone filter or change the box in anyway you lose that sensor. I have mine disconnected because of an intake. That shouldnt be a problem though. If your MAF was messed up then you wouldn't say it was running good. I wouldn't worry too much if it's your air temp sensor. AND FYI insanity, backpressure is a good thing. Why do you think Ferreri has v10's and sti'll a 1 3/4 inch exhaust?

[InsanityInc]

Yo dude, 240's DO have an air intake temp sensor. It is located inside the air box itself. When you put a cone filter or change the box in anyway you lose that sensor.

What engine are you talking about? OBD1 KA24DE, OBD1 KA24E or OBD2 KA24DE? I know for a fact that OBD1 KA24DEs do not have an intake air temperature sensor. There was no such sensor in my airbox, nor any wiring for one or even a place for one to go.

Quote »AND FYI insanity, backpressure is a good thing.[/quote]

No. It isn't. Backpressure inhibits scavenging and causes nothing good. What is actually desirable is exhaust stream velocity, since you can attain a negative pressure (read: less than 0 backpressure) in the exhaust pipe due to bernoulli's principle.

The whole "you need backpressure" myth was started because people found out that they could make better gains with a pipe of a smaller diameter as opposed to a larger one, and people drew VERY wrong conclusions based on that piece of information.Quote »Why do you think Ferreri has v10's and sti'll a 1 3/4 inch exhaust?[/quote]What ferrari has a 1 and 3/4 inch single outlet exhaust? Also, "v10" means nothing about the engine displacement. If they have a 1.0L v10 (some types of formula racing use those, or have in the past), then a 1 3/4" pipe is pretty reasonable if the CFM output is low enough.

[S3t0_S13]

He said that the hose that connects to the intake box has a metal sensor of some sort :/ he says that he has taken it to the mechanic and he had cleaned it out, and the car was running great.right now the symptoms, i can smell gas coming out of my exhasut and i doubt cuz their full 2 3/4 pipes. i dont know what 2 do

[Ni2s4s0aSnX]

Yes, you are wrong Insanity the KA does have an Intake Temperature Sensor, even the S13 KA does. It's on the side on the stock air box, its a little thing on a wire with a tan plastic thing around it. So, you obviously haven't taken a very good look a your engine. Either that, or you're just a 15 year-old ricer kid who doesn't even have a 240sx, which is what I'm assuming. And you're right that backpressure is not a good thing, I'll agree with you on that. I also agree that the problem is that you're running rich.
Modified by Ni2s4s0aSnX at 1:16 PM 12/20/2005

[240crawler]

Yes, you are wring Insanity the KA does have an Intake Temperature Sensor, even the S13 KA does. It's on the side on the stock air box, its a little thing on a wire with a tan plastic thing around it.

If you can show me my ITS, you can screw my girl, sister, and my mom. Really, I have a 91 and it does not, nor has ever had a sensor in the airbox. While I realize that injected motors need a temp reading for the computer to properly adjust fuel, I agree more with the idea that it is part of the MAF.

[Ni2s4s0aSnX]

My 90' has one, thats all I know.

[Skidmark]

The wiring diagram for the '91 has "temperature sensor" on it, but it does not specify what, or where, it is. My car lost it's airbox before I bought it so I can't really comment...

[InsanityInc]

My 90' has one, thats all I know.

That's a KA24E, retard. Completely different engine. Next time you want to call someone a "15 year old ricer who doesn't own a 240" perhaps you should bother to know what the **** you're talking about.

[Ni2s4s0aSnX]

All you said was KA. It's an S13 isn't it? You said S13 don't have them. But you didn't specify which engine, so you can't try to make me look stupid. It's all on you.

[InsanityInc]

All you said was KA. It's an S13 isn't it? You said S13 don't have them. But you didn't specify which engine, so you can't try to make me look stupid. It's all on you.

What engine are you talking about? OBD1 KA24DE, OBD1 KA24E or OBD2 KA24DE? I know for a fact that OBD1 KA24DEs do not have an intake air temperature sensor. There was no such sensor in my airbox, nor any wiring for one or even a place for one to go.

Right there, I say KA24DEs don't have one, and here's the OP:

Quote »Hey guys, i just bought a 1992 240sx hatchback[/quote]If it's a 92, that means it has a KA24DE. So yes, you are stupid and you can't read. Go away.

[Ni2s4s0aSnX]

Ok, that was my bad, I didn't read the whole thing.

[zukitek]

IAT is integral to the MAF on most s13 and s14 vehicles with california and federal emmissions and has been for a number of years on most nissan automobiles Ive come into contact with but its sorta inmaterial because" it barely passed "denotes that it passed,and since its all heresay according to 2nd 3rd maybe even 4th hand info .I input only to make this point ....I have cleaned the element wire of many "hotwire "MAF sensors and brought them right back to life with just a squirt of brake cleaner .Could this maybe be the cleaning that the owner refered to .

Ricky

[deviousKA]

Only the ka24e eccs have a dedicated IAT sensor. This sensor is a thermistor and the circuitry and analog to digital conversion is similar to that of the coolant and egr temp sensors. These particular egr and iat temp channels can be modified to accept any 8 or 10 bit voltage range for extra inputs. The ka24e is the only ecu which supports a streaming register for IAT.

The ka24de S13 has similar circuitry but this IAT sensor has been replaced with a secondary egr temp sensor (thermistor), which is not used on some models.

Iat is not necessary with a hotwire maf ecu system, it is only used for other small environment condition adjustments. The maf doesnt exactly have the seperate iat "built in", it doesnt need it for a fuel calculation due to its nature of operation. This is unlike MAP sensor based ecus which need an iat sensor for part of the density calculation.

[ddgsxr504]

My S14 is OBD2 so here is a picture to verify the existence of an IAT. You can only see the plug from the harness and not the actual sensor but you get the point. If you buy an aftermarket intake that is worth a lick then it will have a fitting that relocates it from the side of the stock airbox to the intake pipe.
Modified by ddgsxr504 at 12:15 PM 1/19/2006

[deviousKA]

I am not certain on the white plug obd2 s14 ecu, the iat sensor may meet certain thresholds used for emissions purposes. It is not used as a continually calculated input for any fueling trim factor, and as far as I know is not a supported register for diagnostic purpose.

Im not exactly answering the question at hand anyways, I would suggest you check the integrity of all harness connections as it is doubtful the iat is your problem.

[skatanic28]

s14's have them for obd2 compliance. i believe the fsm even states that it in know way affects fuel trims.

[SimpleEnigma]

Thanks Devious for putting that question to rest, i think that was about to get ugly.

but just to add my 2 cents. I have a '92 and have torn the entire front half of the motor off after my collision and i have never seen anything that remotely looks like what yall are describing on the intake. if the little black hose thing that runs to a black box on the driver side strut tower is what yall are talking about that would happen to be the PAIR/AIV valve.

the other thing to check is the O2 sensor. in case yall forgot, that sensor is what controls a lot of the fuel/air ratio.

Have you checked your ignition system? cap and rotor, plug wires, spark plugs? i think after those have checked out i would go to the O2 sensor before i look at the MAF, but i definately would check the MAF just to be safe.

I think the O2 sensor more often than not is the cause of most running rich problems.

i am pretty sure i have a spare MAF left over from my parts car. shoot me an email if you need it. just click on my name.

[AmoebAssassin]

Before you go and spend money to replace your MAF, just spray the element gently with some carb cleaner, or use a q-tip and rubbing alcohol. That should de-grease it pretty well. If it still doesnt work, then you should drop the cash for a new one. But it's a part that could easily have just gotten dirty and needs some cleaning.

[ddgsxr504]

If you do have to get a (brand) new one the only place to get it is at the dealer for about $400+ so try searching EBAY first. Mine took a crap about a month ago and I got one off a 96 for my 95 for $31 shipped!!