S14 Engine Problems!

[Sag3r]

My s14 idles fine,but when I drive it and step all the way down it sputters and the loses power. Took it to a mechanic and he said my spark plugs were bad which I had just been changed not even a week from when I took it to him! So I have no idea what it could be im thinking the knock sensor went bad. But not really sure need some help here any suggestions.

[s13gold]

what kind of motor do you have?

[idlafie]

Before we get into what MAY be wrong with your vehicle, it would help if you could provide us with a little bit of information. First & foremost, what model year is your car? How many miles on the motor? Stock intake/exhaust or modified intake/exhaust? Any upgrades? Like 300zx fuel filter or walboro fuel pump? Stock distrubutor cap & rotor & stock spark plug wires?? Lowered suspension with wide tires?? I've seen people do some crazy stuff to their 240's so the aforementioned helps when trying to diagnose engine problems over the net. And yes...I've seen vehicles with lowered suspensions & wide tires wear out the front driver side plastic fenderwell liner & short out the electrical wiring harness above it.

Your loss of power could be due to anything from a dirty fuel filter / dying fuel pump, dying MAF, vacuum leak, etc., etc., etc. First place to start is to check your ECU for a Diagnostic Trouble Code, (DTC), first. You'll have to find a Factory Service Manual, (FSM) for your car to get instructions on how to pull the DTC from your ECU. You'll have to use the SEARCH function here on Zilvia to find a FSM.

Once you do that, post your reply & we'll go from there.

ID

[Sag3r]

Engine:Ka24de
Model:1995
Miles:144xxx
Modes:completely stock
Problem it sounds like it's about to die from 2200rpm's to 3700rpm from then on it runs fine.It hesitates on start sometimes I even have to give it some gas.It feels very slow tremendous loss of power.I checked codes with ob2 and nothing came up.Engine light is not on! So far the car does this when it wants to it's been running fine for the last couple of days and then again it starts running like shit. I always run 92 octane so im sure gas aint the prblem.

[yaba94070]

it sounds like the fuel pump or filter....
but im not entirly sure because you not entirly clear. So you saying that when its not between 2200rpm - 3700rpm it runs fine no problem with deceleration or acceleration???
you will defently need the factory manuel if you gonna do anything your self that way you can read it over and look at the pictures so you don;t have to second guess your self.
look for it online and if you cant find it there and give up then go to a craigns, pepboys, auto zone ect... they usually have them there

[Z U L8R]

Mass Air Flow Sensor!!!! @@ make sure your maf plug is all the way in, check for corrosion, but all in all you're most likely gonna need another one

[pbcstylez]

id like to vote for a vaccuum issue, mine falls on its face as well, i had the MAF code, but r/p the MAF, now im hunting for vaccuum leaks

[Dream240]

Mass Air Flow Sensor!!!! @@ make sure your maf plug is all the way in, check for corrosion, but all in all you're most likely gonna need another one

If it was the MAF sensor, he would be throwing a code. Especially on an OBD-II system.

So that's a negative.

[Z U L8R]

If it was the MAF sensor, he would be throwing a code. Especially on an OBD-II system.

So that's a negative.

not true, i see 96+ maximas and altimas all the time with the same symptom with no check engine light, we get to "try known good mass air flow sensor" replace the maf and the car's fixed.

it would make more sense to be a vacuum leak if the car ran like shit in all rpms or idled high etc but the most common thing on any nissan is a bad maf and running like shit at ~3000 rpm is the exact symptom. plus his plugs were rich with fuel, not a lean condition which a vacuum leak will cause, hence another finger pointing at a fuel trim problem.

it's not getting a signal from the maf dude. either it's a bad maf or a bad connection.

[Dream240]

Or you can just take the existing MAF and measure the voltage readings to the FSM specs, if you dont have an extra one lying around.

It's an easy test that you can do with a simple volt meter.

[s13gold]

your distributor.

[wannabe_drifter]

Did you ever found out ??

[leveloneae86]

If it was the MAF sensor, he would be throwing a code. Especially on an OBD-II system.

So that's a negative.


1995 240sx are obd1. 1996 and up are obd2 according to my researches.

to the op: im battling the same isssue u have. a bad catalytic converter, an exhaust leak, dirty fuel injectors, dirty fuel filter, bad o2 sensor, could alos be causing this.

to see if the injectors are ok u have the car running and unplug the spark wire plug closest to the engine first and see if the car starts to idle funny. if it does then its good and move on to the next one. if the idle doesnt change then u have a bad injector. keep us posted on what caused this and it might cause it on my zenki as well. gl

edit: just realized how old this is. lol

[Dream240]

you're right about the years and their respective OBD setup, but they both have a capable code for a faulty MAF. just the OBD-II require a code reader of some kind to get it, not like the S13s where you just count blips.

Most of the time the maf code is caused by just having a dirty maf sensor. some maf cleaner is always my first course of action.

[bees]

Did you ever found out ??

yeah, did u?

[98s14inaz]

This sounds like what I am going though. I've replaced the following...

-spark plugs
-cap and rotor (my rotor was actually bad but the problem still exists)
-re-checked timing with timing light 20btdc
-new z32 fuel filter
-replaced mafs with a known working one.

I'm still having the same issue, no cels, car falls on face like you hit a wall at 4k rpms. One thing that makes me think it is fuel related is that my fuel gauge works but my gas light never comes on when it gets low. I pulled the cluster and even replaced the bulb. I was told that base model s14's don't have the light hooked up but that seems unlikely. I'm about to replace the fuel pump with a walbro unit.

[wannabe_drifter]

To let anyone know, I've had a similar problem.
Car would run fine if I would just cruise, but as soon as I would step on it even a little it would bog so bad, even a scooter could pass me.

It turned out to be the fuel pump. Test its pressure, if its fine then go for a 2-3 minutes drive without unhooking the pressure gauge and then without turning off the car check the pressure. A guy on local forum only saw that his pressure was too low after a little drive.

Oh yeah and the ECU said it was the knock sensor, but it didn't change a thing... !

[Eul_240SX]

hey buddy check your injectors my car was doing that to